CN103267629B - Point-diffraction interference wave aberration measuring instrument and measuring method thereof - Google Patents

Abstract

A point-diffraction interference wave aberration measuring instrument consists of a light source, a light splitter, a first light intensity and polarization adjuster, a phase shifter, a second light intensity and polarization adjuster, an ideal wave front generating unit, an object precise adjusting platform, a measured optical system, an image wave front detecting unit, an image precise adjusting platform and a data processing unit. The interference instrument has the advantages of simplicity in structure, no systematic error of a phase shifting element, high interference grain visibility and capability of calibrating the systematic error.

Description

Point-diffraction interference wave aberration measuring instrument and detection method

Technical field

The present invention relates to interferometry field, particularly a kind of point-diffraction interference wave aberration measuring instrument and detection method.

Background technology

Wave aberration is the important parameter describing little aberration imaging optical system performance.It is operation wavelength that the microcobjective of high-quality and the wave aberration of space telescope need be less than λ/4PV or λ/14RMS(λ, and RMS is root-mean-square value).The wave aberration of deep-UV lithography projection objective requires to reach several nm RMS, and the wave aberration of extreme ultraviolet lithography projection objective need reach below 1nm RMS.This proposes very high requirement to wave aberration detection technique.

At first technology 1(see H.Medecki, E.Tejnil, K.A.Goldberg, " Phase-shiftingpoint diffraction interferometer ", OPTICS LETTERS Vol.21, No.19,1526-1528,1996) describe the detection of a kind of phase shift point diffraction interferometer for optical system wavefront aberration.After this, the extreme ultraviolet lithography projection objective wave aberration check point diffraction interferometer that U.S. LBNL (Lawrence Berkeley National Laboratory), Japanese EUVA (Extreme UltraVioletLithography System Development Association) research and develop all have employed this technology, and test repeatability reaches 0.1nm RMS.This technology produces standard ball ground roll by pin-hole filter-ing, adopts diffraction grating as beam splitter and phase-shifting element.Any one in diffraction grating 0 order diffraction light and 1 order diffraction light is as measurement light wave, and another is by producing reference light wave after pin-hole filter-ing.Between 0 order diffraction light and 1 order diffraction light, introduce phase shift by the transverse shifting of diffraction grating, realize high precision test.But the light intensity of 0 order diffraction light and 1 order diffraction light is determined by the diffraction efficiency of diffraction grating, non-adjustable.When employing 1 order diffraction light produces reference light wave by pin-hole filter-ing, visibility of interference fringes is too low; When employing 0 order diffraction light produces reference light wave by filtering aperture, the coma that optical grating diffraction produces can affect measuring accuracy, and is difficult to demarcate.Further, adopt diffraction grating as phase-shifting element, diffraction grating is arranged in the imaging optical path of tested imaging system, needs to increase extra displacement platform and carries out phase shift, cause system architecture complicated, add system cost.The factors such as diffraction grating base material refractive index is uneven, in uneven thickness, the defect of diffraction grating pattern, dust also can produce wavefront distortion, produce systematic error.

Summary of the invention

The object of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of point-diffraction interference wave aberration measuring instrument and detection method are provided, to realize the high precision test to optical system wavefront aberration.This interferometer has that structure is simple, phase-shifting element does not produce systematic error, high visibility of interference fringes and can the advantage of function of calibrating systematic error.

Technical solution of the present invention is as follows:

A kind of point-diffraction interference wave aberration measuring instrument, it is characterized in that it is by light source, optical splitter, the first light intensity and polarization state regulator, phase-shifter, second light intensity and polarization state regulator, desirable wavefront generating unit, object space minute adjustment platform, tested optical system, image space Wave-front measurement unit, image space minute adjustment platform, data processing unit forms.

Position and the annexation of above-mentioned each ingredient are:

The output light working direction of light source is optical splitter; Incident light is divided into the adjustable light path of light path and light path fixed light path by optical splitter; The first light intensity and polarization state regulator light path that light path is adjustable connect the first light intensity and polarization state regulator, phase-shifter, access the first input end of desirable wavefront generating unit afterwards, before or after can be connected to phase-shifter; Light path fixed light path connects the second light intensity and polarization state regulator, access the second input end of desirable wavefront generating unit afterwards; First output terminal of desirable wavefront generating unit and the second output terminal are positioned at the object plane of tested optical system; Desirable wavefront generating unit is supported and precision positioning by object space minute adjustment platform; Image space Wave-front measurement unit is positioned at the image space of tested optical system; Image space Wave-front measurement unit is supported and precision positioning by image space minute adjustment platform; The output signal input data processing unit of image space Wave-front measurement unit processes, and extracts wave aberration information.

Described light source is laser instrument, light emitting diode, super-radiance light emitting diode, or monochromator.Described light source can be the light source that optical fiber exports, and also can be the light source that free space collimation exports.

Described optical splitter is the beam splitter that incident light can be divided into two-beam, and as fiber coupler, Amici prism, one side is coated with the glass plate of spectro-film.

The first described light intensity and polarization state regulator and the second light intensity and polarization state regulator are the devices that can regulate luminous power by light and polarization state, can be made up of, also can only be made up of a rotatable analyzer adjustable attenuator and Polarization Controller;

The first described light intensity and polarization state regulator and the second light intensity and polarization state regulator also just can regulate the device of the luminous power by light path, can be made up of, also can only be made up of an adjustable attenuator Polarization Controller and analyzer;

The first described light intensity and polarization state regulator and the second light intensity and polarization state regulator can adopt identical structure, also can adopt different structures.

Described adjustable attenuator is a regulating optical power and does not change the device of polarisation of light state, as be coated with at different sector region differential declines film rotary glass sheet, by blocking the iris of light path regulating optical power.

Described Polarization Controller is the device that can change polarisation of light state, as rotatable half-wave plate, or the rotatable quarter wave plate connected successively, rotatable half-wave plate, and the combination of rotatable quarter wave plate; Described analyzer be only allow the linearly polarized light in a direction through element, as polaroid, polarizing prism.

Described phase-shifter is the device that can change light path light path, as being wrapped in the single-mode fiber ring on column piezoelectric ceramics, by changing the driving voltage of column piezoelectric ceramics, stretching single-mode fiber, changes light path; The variable optical delay line of the element compositions such as beam splitter prism, catoptron, piezoelectric ceramics, drives catoptron or prism motion to change light path by piezoelectric ceramics.

Described desirable wavefront generating unit is that to convert within the scope of the object-side numerical aperture of tested optical system be standard ball ground roll by the light from its first input end and the input of the second input end, and respectively from the optical module that its first output terminal or the second output terminal export, the centre distance s between the first output terminal of desirable wavefront generating unit and the second output terminal _obe greater than the enlargement factor of diameter divided by tested optical system of tested optical system diffusion of point image spot.

Described desirable wavefront generating unit is made up of the first optical fiber and the second optical fiber; The input end of the first optical fiber is the first input end of desirable wavefront generating unit, and output terminal is the first output terminal of desirable wavefront generating unit; The input end of the second optical fiber is the second input end of desirable wavefront generating unit, and output terminal is the second output terminal of desirable wavefront generating unit; First optical fiber and the second optical fiber are single-mode fibers, and the first optical fiber and the second optical fiber also can be polarization maintaining optical fibres; The output terminal core diameter Φ of the first optical fiber and the second optical fiber _fbe less than the object space resolution of diffraction of described tested optical system, meet Φ _f< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system.

Described desirable wavefront generating unit also can be made up of the 3rd optical fiber, the 4th optical fiber, imaging lens group, object plane mask; The input end of the 3rd optical fiber is the first input end of desirable wavefront generating unit, and output terminal is positioned at the object plane of imaging lens group; The input end of the 4th optical fiber is the second input end of desirable wavefront generating unit, and output terminal is positioned at the object plane of imaging lens group; Object plane mask is positioned at the image planes of imaging lens group; Object plane mask there are the first circular hole and the second circular hole; First circular hole is the first output terminal of desirable wavefront generating unit, and the second circular hole is the second output terminal of desirable wavefront generating unit; The output terminal of the 3rd optical fiber is imaged on the second circular hole through imaging lens group, and the output terminal of the 4th optical fiber is imaged on the first circular hole through imaging lens group; 3rd optical fiber and the 4th optical fiber are single-mode fibers, and the 3rd optical fiber and the 4th optical fiber also can be polarization maintaining optical fibres; The diameter of phi o of the first circular hole and the second circular hole is less than the object space resolution of diffraction of described tested optical system, and meet Φ o< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system.

Described desirable wavefront generating unit also can be made up of the first catoptron, the second catoptron, focus lamp group, object plane mask; Two bundle collimated light first light beams and the second light beam are respectively from first input end, the second input end input of desirable wavefront generating unit; Along the first light beam working direction, successively through the first catoptron, focus lamp group and object plane mask; Along the second light beam working direction, successively through the second catoptron, focus lamp group and object plane mask; Object plane mask is positioned on the back focal plane of focus lamp group; Object plane mask there are the first circular hole and the second circular hole; First circular hole and second round hole part of object plane mask are divided into photic zone, and other parts are light tight district; First circular hole is the first output terminal of desirable wavefront generating unit, and the second circular hole is the second output terminal of desirable wavefront generating unit; The diameter of phi o of the first circular hole and the second circular hole is less than the object space resolution of diffraction of described tested optical system, and meet Φ o< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system; Have an angle between first catoptron and the second catoptron, make the first light beam focus on the first output terminal by focus lamp group, the second light beam focuses on the second output terminal by focus lamp group.

The element that described optical splitter, adjustable attenuator, Polarization Controller, analyzer, phase-shifter can be optical fiber inputs, optical fiber exports, also can be the element of free space input, free space output, also can be the element of optical fiber input, free space output, also can be the element of free space input, optical fiber output; As the input end connecting fiber coupled lens at optical fiber input element, become free space input element; At the input end of free space input element along optical transmission direction successively connecting fiber and fiber collimating lenses, become optical fiber input element; At the output terminal connecting fiber collimation lens of optical fiber output element, become free space output element; At the output terminal of free space output element along optical transmission direction successively connecting fiber coupled lens and optical fiber, become optical fiber output element.

Light path that described light path is adjustable and light path fixed light path can be optic fibre light paths, also can be free space light paths, and can a part be also optic fibre light path, a part be free space light path; Namely in the described adjustable light path of light path between the first light intensity and polarization state regulator, phase-shifter, desirable wavefront generating unit, and light path fixed light path can use Fiber connection between the second light intensity and polarization state regulator, desirable wavefront generating unit, also can connect with free space, also can part Fiber connection, a part connects with free space; Catoptron, prism etc. can be had in free space light path to adjust the element of direction of beam propagation, also can have beam expanding lens group, beam-shrinked mirror group etc. change the element of beam size; The element of the connecting fibers such as end optical fiber flange plate can be had in optic fibre light path.

Described object space minute adjustment platform the first output terminal of desirable wavefront generating unit and the second output terminal to be adjusted to multiple degrees of freedom displacement platform in tested optical system true field or adjustment rack.

Described image space Wave-front measurement unit by image space mask, photoelectric sensor, to be configured to.

Described image space mask is positioned at the image planes of tested optical system; Image space mask comprises optical transmission window and filtering circular hole; Filtering circular hole is the printing opacity aperture that diameter of phi i is less than the image space resolution of diffraction of described tested optical system, meets Φ i< λ/(2NAi), and wherein λ is optical source wavelength, and NAi is the image-side numerical aperture of tested optical system.Optical transmission window be can unscreened while through the transmission region of the quadrilateral of the first output terminal of described desirable wavefront generating unit and the diffusion of point image spot of the second output terminal after tested optical system imaging, annular or other shapes.

When one-shot measurement only detects a some position, visual field of tested optical system, position relationship between optical transmission window and filtering circular hole meets when the first output terminal of desirable wavefront generating unit or the picture point of the second output terminal after tested optical system imaging are centrally located at filtering circular hole position, the diffusion of point image spot of another output terminal can be unscreened through optical transmission window, and do not have light-transmissive optical transmission window at the diffusion of point image spot of filtering circular hole position, as: optical transmission window is quadrilateral transmission region, filtering circular hole is had in optical transmission window side, distance between the center of filtering circular hole and the nearer edge of optical transmission window Distance Filter circular hole is slightly larger than the diffusion of point image spot radius of tested optical system.

When one-shot measurement needs to detect tested optical system two some positions, visual field, position relationship between optical transmission window and filtering circular hole meets when the picture point of any one in first output terminal and the second output terminal of desirable wavefront generating unit after tested optical system imaging is centrally located at filtering circular hole position, the diffusion of point image spot of another output terminal can be unscreened through optical transmission window, and do not have light-transmissive optical transmission window at the diffusion of point image spot of filtering circular hole position, as: optical transmission window is " returning " font or annular transmission region, filtering circular hole is positioned at the center in light tight region inside optical transmission window, or optical transmission window is quadrilateral transmission region, has filtering circular hole respectively in optical transmission window both sides, or the optical transmission window region of quadrilateral or other shapes is had in filtering circular hole both sides, further, in said structure, the distance between the center of filtering circular hole and the nearer edge of optical transmission window Distance Filter circular hole is slightly larger than the diffusion of point image spot radius of tested optical system.

Described photoelectric sensor is that two-dimensional detector or transform optics mirror group and two-dimensional detector are formed, the photoelectric sensor be made up of transform optics mirror group and two-dimensional detector, image space mask is positioned at the front focal plane of described transform optics mirror group, and described two-dimensional detector is positioned at the back focal plane of transform optics mirror group.

Described transform optics mirror group is can simple lens, lens combination, the catoptron group of imaging.

Described two-dimensional detector is the 2 D photoelectric switching device that light signal can be converted to electric signal, as CCD, CMOS, or photodiode array; Namely the output signal of two-dimensional detector is the output signal of image space Wave-front measurement unit.

Described support is used to the mechanical parts supporting image space mask and photoelectric sensor.

Described support can comprise fixed part and minute adjustment parts; Fixed part maintains static when system works, and minute adjustment parts can the position of accurate adjustment image space mask in system works, realizes fine registration; Minute adjustment member supporting is on fixed part, and image space mask support is on minute adjustment parts, and photoelectric sensor is supported on fixed part.Minute adjustment parts can be piezoelectric ceramics adjustment racks, also can be that voice coil motor adjustment rack etc. can the governor motion of minute adjustment position.

Described fine registration is adjusted by the position of image space mask, an output terminal of desirable wavefront generating unit is aimed at by the center of the picture point of tested optical system with the filtering circular hole of image space mask, the picture point of another output terminal is positioned at the optical transmission window inside of image space mask, or makes the picture point of two output terminals of desirable wavefront generating unit all be positioned at the optical transmission window inside of image space mask.

Described support also only can comprise fixed part, does not comprise minute adjustment parts.

Described image space minute adjustment platform is multiple degrees of freedom displacement platform or the adjustment rack that can regulate image space Wave-front measurement cell position; By the adjustment of image space minute adjustment platform, picture point and the image space mask registration of the output terminal of desirable wavefront generating unit can be made, namely enter the fine registration range of adjustment of the minute adjustment parts in support.When not comprising minute adjustment parts in support, described fine registration is realized separately by image space minute adjustment platform.

Described data processing unit stores interferogram, carries out interferogram analysis process to obtain computing machine or the embedded system of wave aberration.

Utilize above-mentioned point-diffraction interference wave aberration measuring instrument to detect the method for tested optical system wavefront aberration, it is characterized in that the method comprises the following steps:

1) mobile object space minute adjustment platform, makes the first output terminal of desirable wavefront generating unit or/and the second output terminal is positioned at the position that tested optical system needs the visual field point measured;

2) if the first output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, mobile image space minute adjustment platform, carry out fine registration, the picture point of the first output terminal of desirable wavefront generating unit is aimed at the center of the filtering circular hole of image space mask, the picture point of the second output terminal is positioned at the optical transmission window inside of image space mask, then enters step 3); If the first output terminal position of desirable wavefront generating unit is not the position that tested optical system needs the visual field point measured, directly enter step 4);

3) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of interferogram is expressed as Ia1 successively, Ia2,, Iam, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _a, WR _apHASE DISTRIBUTION W is obtained after Phase-un-wrapping _a;

4) if the second output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, mobile image space minute adjustment platform, carry out fine registration, the picture point of the second output terminal of desirable wavefront generating unit is aimed at the center of the filtering circular hole of image space mask, the picture point of the first output terminal is positioned at the optical transmission window inside of image space mask, then enters step 5); If the second output terminal position of desirable wavefront generating unit is not the position that tested optical system needs the visual field point measured, directly enter step 6);

5) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of this interferogram is expressed as Ib1 successively, Ib2,, Ibm, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _b, WR _bpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _b;

6) carry out fine registration, make the picture point of two output terminals of desirable wavefront generating unit all be positioned at the optical transmission window inside of image space mask;

7) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of this interferogram is expressed as Ic1 successively, Ic2,, Icm, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _c, WR _cpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _c;

8) if the first output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, then formula W is utilized ₁=W _a-W _ccalculate the wave aberration W of tested optical system at this visual field point ₁; If the second output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, then utilize formula W ₂=W _c-W _bcalculate the wave aberration W of this visual field point ₂.

Described phase shift interference phase extraction algorithms is the computing method of the wrapped phase distribution that the light distribution calculation interferogram of the interferogram successively each other by a group with phase-shift phase δ is carried; As equaled pi/2 as phase-shift phase δ, when interferogram quantity m equals 3, described phase shift interference phase extraction algorithms can be as the formula (1)

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{I_{*3}-I_{*2}}{I_{*1}-I_{*2}}\right);---\left(1\right)$

When phase-shift phase δ equals pi/2, when interferogram quantity m equals 4, described phase shift interference phase extraction algorithms can be as the formula (2)

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{I_{*4}-U_{*2}}{I_{*1}-I_{*3}}\right);---\left(2\right)$

When phase-shift phase δ equals pi/2, when interferogram quantity m equals 5, described phase shift interference phase extraction algorithms can be as the formula (3)

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{2(I_{*4}-I_{*2})}{I_{*1}-2I_{*3}+I_{*5}}\right);---\left(3\right)$

When phase-shift phase δ equals 2 π/m, during interferogram quantity m >=3, described phase shift interference phase extraction algorithms can be as the formula (4)

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{-\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{I}_{*i}\sin (i\&times;\mathrm{\&delta;})}{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{I}_{*i}\cos (i\&times;\mathrm{\&delta;})}\right);---\left(4\right)$

In formula (1) ~ (4), * represents a, b or c.

The present invention has the following advantages:

(1) luminous power and the polarization state that participate in the two-beam of interfering in interferometer are adjustable arbitrarily, can produce high interference visibility;

(2) phase-shifter described in is positioned at beyond tested imaging system images light path, and test system structure is simple, flexibly; Such as this interferometer is applied in litho machine, does not need to increase extra displacement platform, be convenient to the in situ detection realizing wave aberration of photoetching projection objective;

(3) desirable wavefront generating unit can filtering along before the tested optical system of optical transmission direction optical element produce wavefront distortion, Systematic error sources is few, easily realizes high precision test;

(4) can demarcate and eliminate systematic error.

Accompanying drawing explanation

Fig. 1 is the structural representation of point-diffraction interference wave aberration measuring instrument of the present invention;

Fig. 2 is the structural representation of several embodiments of the present invention first light intensity and polarization state regulator;

Fig. 3 is the structural representation of two embodiments of phase-shifter of the present invention;

Fig. 4 is the structural representation of first embodiment of the desirable wavefront generating unit of the present invention;

Fig. 5 is the structural representation of second embodiment of the desirable wavefront generating unit of the present invention;

Fig. 6 is the structural representation of object plane mask in the embodiment of the desirable wavefront generating unit of the present invention;

Fig. 7 is the structural representation of the 3rd embodiment of the desirable wavefront generating unit of the present invention;

Fig. 8 is the structural representation of several embodiments of image space Wave-front measurement unit of the present invention;

Fig. 9 is several example structure schematic diagram of image space mask of the present invention;

Figure 10 is the structural representation of a point-diffraction interference wave aberration measuring instrument of the present invention embodiment;

Figure 11 is the structural representation of a point-diffraction interference wave aberration measuring instrument of the present invention embodiment.

Embodiment

Below in conjunction with accompanying drawing and embodiment, the present invention will be further described, but should not limit the scope of the invention with this embodiment.

As shown in Figure 1, point-diffraction interference wave aberration measuring instrument of the present invention comprises: light source 1, optical splitter 2, the first light intensity and polarization state regulator 3, phase-shifter 4, second light intensity and polarization state regulator 5, desirable wavefront generating unit 6, object space minute adjustment platform 7, tested optical system 8, image space Wave-front measurement unit 9, image space minute adjustment platform 10 and data processing unit 11.Described image space Wave-front measurement unit 9 is made up of image space mask 901, photoelectric sensor 902, support 903, image space mask 901 comprises optical transmission window 901b and filtering circular hole 901a(can have multiple filtering circular hole, as the first filtering circular hole 901a1, the second filtering circular hole 901a2 etc.), photoelectric sensor 902 comprises a two-dimensional detector 902b.

Position and the annexation of above-mentioned each ingredient are:

Exporting in light working direction at light source 1 is optical splitter 2; Incident light is divided into the adjustable light path 2A of light path and light path fixed light path 2B by optical splitter 2; Connection first light intensity and polarization state regulator 3 on light path is adjustable light path 2A, phase-shifter 4, accesses the first input end 6A of desirable wavefront generating unit 6 afterwards, before or after the first light intensity and polarization state regulator 3 can be placed on phase-shifter 4; Placement second light intensity and polarization state regulator 5 on light path fixed light path 2B, access the second input end 6B of desirable wavefront generating unit 6 afterwards; First output terminal 6C of desirable wavefront generating unit 6 and the second output terminal 6D is positioned at the object plane of tested optical system 8; Desirable wavefront generating unit 6 is supported and precision positioning by object space minute adjustment platform 7; Image space Wave-front measurement unit 9 is positioned at the image space of tested optical system 8, and the image space mask 901 of image space Wave-front measurement unit 9 is positioned at the image planes of tested optical system 8, and the two-dimensional detector 902b of photoelectric sensor 902 is positioned at along after light working direction image space mask 901; Image space Wave-front measurement unit 9 is supported and precision positioning by image space minute adjustment platform 10; The output signal input data processing unit 11 of image space Wave-front measurement unit 9.

Principle of work of the present invention and the course of work as follows:

The output light of light source 1 is divided into the adjustable light path 2A of light path and light path fixed light path 2B after optical splitter 2; Light through the adjustable light path 2A of light path and light path fixed light path 2B produces a standard ball ground roll at the first output terminal 6C of desirable wavefront generating unit 6 or the second output terminal 6D respectively; First output terminal 6C of desirable wavefront generating unit 6 or the second output terminal 6D is adjusted in tested optical system 8 true field the position needing the visual field point measured by object space minute adjustment platform 7; Standard ball ground roll does not have wave aberration, the i.e. wave aberration Ws=0 of standard ball ground roll, two standard ball ground rolls can carry the wave aberration of the first output terminal 6C and the second visual field, output terminal 6D place point respectively after tested optical system 8, namely produce the wavefront distortion identical with the wave aberration of two visual field points; Tested optical system 8 is W in the wave aberration of the visual field point at the first output terminal 6C place of desirable wavefront generating unit 6 ₁, be W in the wave aberration of the visual field point at the second output terminal 6D place of desirable wavefront generating unit 6 ₂.

Mobile image space minute adjustment platform 10, makes the picture point of the first output terminal 6C of desirable wavefront generating unit 6 aim at the center of the filtering circular hole 901a of image space mask 901, and the picture point of the second output terminal 6D is positioned at the optical transmission window 901b inside of image space mask 901; Corrugated through filtering circular hole 901a will become standard ball ground roll, its wave aberration Ws=0 again; Do not changed by the corrugated of optical transmission window 901b, wave aberration still equals the wave aberration W of the visual field point at the second output terminal 6D place of desirable wavefront generating unit 6 ₂; Free space between image space mask 901 and two-dimensional detector 902b and optical element can be given by introducing interferometer system error W between two corrugateds of image space mask 901 _sYS; Two corrugateds are interfered mutually, the PHASE DISTRIBUTION W that interferogram carries _aas the formula (5):

W _a＝W ₂-W _S+W _SYS＝W ₂+W _SYS。（5）

Mobile image space minute adjustment platform 10, makes the picture point of the second output terminal 6D of desirable wavefront generating unit 6 aim at the center of the filtering circular hole 901a of image space mask 901, and the picture point of the first output terminal 6C is positioned at the optical transmission window 901b inside of image space mask 901; Corrugated through filtering circular hole 901a will become standard ball ground roll, its wave aberration Ws=0 again; Do not changed by the corrugated of optical transmission window 901b, wave aberration still equals the wave aberration W of the visual field point at the first output terminal 6C place of desirable wavefront generating unit 6 ₁; Free space between image space mask 901 and two-dimensional detector 902b and optical element still can be given by introducing interferometer system error W between two corrugateds of image space mask 901 _sYS; Two corrugateds are interfered mutually, the PHASE DISTRIBUTION W that interferogram carries _bas the formula (6):

W _b＝W _S-W ₁+W _SYS＝-W ₁+W _SYS。（6）

Mobile image space minute adjustment platform 10, makes the picture point of two output terminals of desirable wavefront generating unit 6 all be positioned at the optical transmission window 901b inside of image space mask 901; Then do not changed by two corrugateds of optical transmission window 901b, be respectively the wave aberration W of the visual field point at the first output terminal 6C place of desirable wavefront generating unit 6 ₁, the second output terminal 6D place the wave aberration W of visual field point ₂; Free space between image space mask 901 and two-dimensional detector 902b and optical element still can be given by introducing interferometer system error W between two corrugateds of image space mask 901 _sYS; Two corrugateds are interfered mutually, the PHASE DISTRIBUTION W that interferogram carries _cas the formula (7):

W _c＝W ₂-W ₁+W _SYS。（7）

Therefore, the wave aberration W of the visual field point at the first output terminal 6C place of desirable wavefront generating unit 6 ₁try to achieve by formula (8):

W ₁＝W _a-W _c。（8）

The wave aberration W of the visual field point at the second output terminal 6D place of desirable wavefront generating unit 6 ₂try to achieve by formula (9):

W ₂＝W _c-W _b。（9）

Owing to coming from the adjustable light path 2A of light path and light path fixed light path 2B respectively by two corrugateds of image space mask 901, therefore, regulate the first light intensity on the adjustable light path 2A of light path and polarization state regulator 3, light intensity and the polarization state on a corrugated can be regulated, regulate the second light intensity on light path fixed light path 2B and polarization state regulator 5, light intensity and the polarization state on another corrugated can be regulated; When the polarization state on two corrugateds is all identical with light intensity, interference visibility reaches maximal value 1; Polarization state when two corrugateds is linearly polarized light, and when polarization direction is orthogonal, does not interfere, and interference visibility is 0; When the polarization state on two corrugateds is identical, the light intensity on a corrugated is I _w1, the light intensity on another corrugated is I _w2time, interference visibility η as the formula (10):

$\mathrm{\&eta;}=\frac{2\sqrt{I_{W1}{I}_{W2}}}{I_{W1}+I_{W2}},---\left(10\right)$

Therefore, by regulating the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5 can realize higher interference visibility.

Same owing to coming from the adjustable light path 2A of light path and light path fixed light path 2B respectively by two corrugateds of image space mask 901, phase-shifter 4 regulates the light path of the adjustable light path 2A of light path that the phase place on a corrugated can be made to change, produce phase shift, thus phase shift interference can be utilized to realize high precision test.

Fig. 2 is the structural representation of several embodiments of the present invention first light intensity and polarization state regulator 3.

The first light intensity shown in Fig. 2 (a) and polarization state regulator 3 are made up of adjustable attenuator 301 and Polarization Controller 302; Along light working direction, before or after adjustable attenuator 301 is connected to Polarization Controller 302.

The first light intensity shown in Fig. 2 (b) and polarization state regulator 3 are made up of analyzer 303 and turntable 304; Turntable 304 drives analyzer 303 to rotate, and changes the light transmission shaft direction of analyzer 303, changes and exports polarisation of light direction and light intensity.

The first light intensity shown in Fig. 2 (c) and polarization state regulator 3 are made up of Polarization Controller 302 and analyzer 303, along light working direction, connect Polarization Controller 302 and analyzer 303 successively; Regulated by polarisation of light state by Polarization Controller 302, change the light intensity by analyzer 303.

The first light intensity shown in Fig. 2 (d) and polarization state regulator 3 are adjustable attenuators 301, only regulate the luminous power by light path.

Second light intensity and polarization state regulator 5 can adopt the structure identical with polarization state regulator 3 with the first light intensity, also can adopt different structures.

Fig. 3 is the structural representation of two embodiments of phase-shifter 4 of the present invention.

Phase-shifter 4 shown in Fig. 3 (a) is made up of column piezoelectric ceramics 401 and the single-mode fiber ring 402 be wound around thereon, by changing the driving voltage of column piezoelectric ceramics 401, the diameter of column piezoelectric ceramics 401 can change, and changes the length of single-mode fiber ring 402, thus changes light path.

Phase-shifter 4 shown in Fig. 3 (b) by beam splitter prism 403, catoptron 404, piezoelectric ceramics 405 forms, along incident light working direction, place beam splitter prism 403, in beam splitter prism reflected light direction, place catoptron 404, through beam splitter prism 403 outgoing after light reflects on catoptron 404, catoptron 404 is arranged on piezoelectric ceramics 405, and change the driving voltage of piezoelectric ceramics 405, the length of piezoelectric ceramics 405 changes, drive catoptron 404 to move, thus change light path.

Fig. 4 is the structural representation of first embodiment of the desirable wavefront generating unit 6 of the present invention.As shown in Figure 4, desirable wavefront generating unit 6 is made up of the first optical fiber 601 and the second optical fiber 602; The input end of the first optical fiber is the first input end 6A of desirable wavefront generating unit 6, and output terminal is the first output terminal 6C of desirable wavefront generating unit 6; The input end of the second optical fiber is the second input end 6B of desirable wavefront generating unit 6, and output terminal is the second output terminal 6D of desirable wavefront generating unit 6; First optical fiber 601 and the second optical fiber 602 are single-mode fibers, and the first optical fiber 601 and the second optical fiber 602 also can be polarization maintaining optical fibres; The output terminal core diameter Φ of the first optical fiber 601 and the second optical fiber 602 _fbe less than the object space resolution of diffraction of described tested optical system 8, meet Φ _f< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system 8.Because the first optical fiber 601 and the second optical fiber 602 are single-mode fiber or polarization maintaining optical fibre, only have a mode transfer in a fiber, and their output terminal core diameter Φ _fbe less than the object space resolution of diffraction of described tested optical system 8, therefore, their output light field is standard ball ground roll in the object-side numerical aperture NAo of tested optical system 8, is converted into standard ball ground roll exports from the first output terminal 6C and the second output terminal 6D respectively from the light of first input end 6A and the second input end 6B input.Centre distance between the output terminal fibre core of the first optical fiber 601 and the second optical fiber 602 is greater than the enlargement factor of diameter divided by tested optical system 8 of tested optical system 8 diffusion of point image spot, diameter as tested optical system 8 diffusion of point image spot is 2 μm, enlargement factor is 1/5, then the centre distance between the output terminal fibre core of the first optical fiber 601 and the second optical fiber 602 is greater than 10 μm.

Fig. 5 is the structural representation of second embodiment of the desirable wavefront generating unit 6 of the present invention.Desirable wavefront generating unit 6 also can be made up of the 3rd optical fiber 603, the 4th optical fiber 604, imaging lens group 605, object plane mask 606, and Fig. 6 is the structural representation of object plane mask 606; The input end of the 3rd optical fiber 603 is first input end 6A of desirable wavefront generating unit 6, and output terminal is positioned at the object plane of imaging lens group 605; The input end of the 4th optical fiber is the second input end 6B of desirable wavefront generating unit 6, and output terminal is positioned at the object plane of imaging lens group 605; Object plane mask 606 is positioned at the image planes of imaging lens group 605; Object plane mask 606 there is the first circular hole 606a and the second circular hole 606b; Second output terminal 6D of the first circular hole 606a to be the first output terminal 6C of desirable wavefront generating unit 6, the second circular hole 606b be desirable wavefront generating unit 6; The output terminal of the 3rd optical fiber 603 is imaged on the second circular hole 606b through imaging lens group 605, and the output terminal of the 4th optical fiber 604 is imaged on the first circular hole 606a through imaging lens group 605; 3rd optical fiber 603 and the 4th optical fiber 604 are single-mode fiber or polarization maintaining optical fibre; The diameter of phi o of the first circular hole 606a and the second circular hole 606b is less than the object space resolution of diffraction of described tested optical system 8, meet Φ o< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system 8.On object plane mask 606, the first circular hole 606a and the second circular hole 606b has filter action to light field, diameter of phi o due to them is less than the object space resolution of diffraction of described tested optical system 8, and their output light field is standard ball ground roll in the object-side numerical aperture NAo of tested optical system 8.Be converted into standard ball ground roll from the light of first input end 6A and the second input end 6B input to export from the second output terminal 6D and the first output terminal 6C respectively.Centre distance on object plane mask 606 between first circular hole 606a and the second circular hole 606b is greater than the enlargement factor of diameter divided by tested optical system 8 of tested optical system 8 diffusion of point image spot, diameter as tested optical system 8 diffusion of point image spot is 1 μm, enlargement factor is 1/5, then the centre distance between the first circular hole 606a and the second circular hole 606b is greater than 5 μm.

Fig. 7 is the structural representation of the 3rd embodiment of the desirable wavefront generating unit 6 of the present invention.Desirable wavefront generating unit 6 is made up of the first catoptron 607, second catoptron 608, focus lamp group 609, object plane mask 606; Two bundle collimated light first light beam 6L1 and the second light beam 6L2 input from the first input end 6A of desirable wavefront generating unit 6, the second input end 6B respectively; Along the first light beam 6L1 working direction, successively through the first catoptron 607, focus lamp group 609 and object plane mask 606; Along the second light beam 6L2 working direction, successively through the second catoptron 608, focus lamp group 609 and object plane mask 606; Object plane mask 606 is positioned on the back focal plane of focus lamp group 609; Second output terminal 6D of the first circular hole 606a to be the first output terminal 6C of desirable wavefront generating unit 6, the second circular hole 606b be desirable wavefront generating unit 6 on object plane mask 606; Have an angle between first catoptron 607 and the second catoptron 608, make the first light beam 6L1 focus on the first output terminal 6C by focus lamp group 609, the second light beam 6L2 focuses on the second output terminal 6D by focus lamp group 609.As described in the explanation of second embodiment of the structure of object plane mask 606 and effect wavefront generating unit 6 as desirable in the present invention.Be converted into standard ball ground roll at the light inputted from first input end 6A and the second input end 6B to export from the first output terminal 6C and the second output terminal 6D respectively.

Fig. 8 is the structural representation of several embodiments of image space Wave-front measurement unit 9 of the present invention.Image space Wave-front measurement unit 9 is made up of image space mask 901, photoelectric sensor 902, support 903.Image space mask 901 is positioned at the image planes of tested optical system 8; Along light working direction, after image space mask 901, place photoelectric sensor 902; Support 903 is used to the mechanical parts supporting image space mask 901 and photoelectric sensor 902.

In Fig. 8 (a), photoelectric sensor 902 comprises transform optics mirror group 902a and two-dimensional detector 902b.Image space mask 901 is positioned at the front focal plane of transform optics mirror group 902a, and two-dimensional detector 902b is positioned at the back focal plane of transform optics mirror group 902a.Transform optics mirror group 902a is can the simple lens of imaging.Two-dimensional detector 902b is CCD.

Fig. 8 (b) medium-height trestle 903 comprises fixed part 903a and minute adjustment parts 903b.Minute adjustment parts 903b is supported on fixed part 903a, and image space mask 901 is supported on minute adjustment parts 903b, and photoelectric sensor 902 is supported on fixed part 903a.Minute adjustment parts 903b can the position of accurate adjustment image space mask 901 in system works, realizes fine registration; Fixed part 903a maintains static when system works.Minute adjustment parts 903b adopts has the piezoelectric ceramics nanometer resolution regulating platform that XYZ tri-regulates degree of freedom.

Described fine registration is adjusted by the position of image space mask 901, make an output terminal (the first output terminal 6C of desirable wavefront generating unit 6, or the second output terminal 6D) aimed at by the center of the picture point of tested optical system 8 with the filtering circular hole 901a of image space mask 901, another output terminal (the second output terminal 6D, or the first output terminal 6C) picture point to be positioned at the optical transmission window 901b of image space mask 901 inner, or make the picture point of two output terminals of desirable wavefront generating unit 6 (the first output terminal 6C and the second output terminal 6D) all be positioned at the optical transmission window 901b inside of image space mask 901.

In Fig. 8 (c), photoelectric sensor 902 only comprises two-dimensional detector 902b.Two-dimensional detector 902b is placed on along after image space mask 901 in light working direction; And it is parallel with image space mask 901.

Fig. 8 (a), Fig. 8 (c) medium-height trestle 903 only include fixed part 903a, do not comprise minute adjustment parts 903b.

When support 903 comprises minute adjustment parts 903b, described image space minute adjustment platform 10 is multiple degrees of freedom displacement platform or the adjustment rack that can regulate image space Wave-front measurement unit 9 position; By the adjustment of image space minute adjustment platform 10, the output terminal of desirable wavefront generating unit 6 (the first output terminal 6C and the second output terminal 6D) can be made to be aimed at image space mask 901 by the picture point of tested optical system 8, namely enter the fine registration range of adjustment of the minute adjustment parts 903b of support 903.

When support 903 only includes fixed part 903a, when not comprising minute adjustment parts 903b, described fine registration is realized separately by image space minute adjustment platform 10.

Fig. 9 is several example structure schematic diagram of image space mask 901 of the present invention.

In Fig. 9 (a), Fig. 9 (b), image space mask 901 comprises an an optical transmission window 901b and filtering circular hole 901a; Filtering circular hole 901a is the printing opacity aperture that diameter of phi i is less than the image space resolution of diffraction of described tested optical system, meet Φ i< λ/(2NAi), wherein λ is optical source wavelength, and NAi is the image-side numerical aperture of tested optical system 8.Optical transmission window 901b be can unscreened while through the first output terminal 6C of described desirable wavefront generating unit 6 and the transmission region of the diffusion of point image spot of the second output terminal 6D after the imaging of tested optical system 8, in Fig. 9 (a), optical transmission window 901b is " returning " font, and in Fig. 9 (b), optical transmission window 901b is annular.In image space mask 901, the part of optical transmission window 901b and filtering circular hole 901a is transmission region, and other parts are for there being the light tight district of light shield layer.Filtering circular hole 901a is positioned at the center in the light tight region inside optical transmission window 901b.Optical transmission window 901b has two edges, and inner side edge is comparatively near along 901b_S1 Distance Filter circular hole 901a, and the center of filtering circular hole 901a and optical transmission window 901b inner side edge are along the diffusion of point image spot radius of the bee-line between 901b_S1 slightly larger than tested optical system 8.When image space mask 901 adopts Fig. 9 (a), Fig. 9 (b) structure, some position, tested optical system two visual fields can be detected in one-shot measurement.

Described light shield layer can be the metal level such as chromium, aluminium, or Mo/Si multilayer film etc. has the rete of obviously decay to transmitted light.

In Fig. 9 (c), the optical transmission window 901b of image space mask 901 is made up of the region that two are separated, the first optical transmission window region 901b1 and the second optical transmission window region 901b2, and image space mask 901 also comprises a filtering circular hole 901a; The feature of filtering circular hole 901a is identical with the filtering circular hole 901a in Fig. 9 (a), Fig. 9 (b); First optical transmission window region 901b1 and the second optical transmission window region 901b2 be all can unscreened while through the first output terminal 6C of described desirable wavefront generating unit 6 and the quadrilateral transmission region of the diffusion of point image spot of the second output terminal 6D after the imaging of tested optical system 8.In image space mask 901, the part of the first optical transmission window region 901b1, the second optical transmission window region 901b2, filtering circular hole 901a is transmission region, and other parts are for there being the light tight district of light shield layer.First optical transmission window region 901b1 and the second optical transmission window region 901b2 lays respectively at the filtering circular hole 901a left and right sides.First optical transmission window region 901b1 and the second optical transmission window region 901b2 all only has 1 edge, be respectively 901b1_S1,901b2_S1, the center of filtering circular hole 901a and the bee-line between edge 901b1_S1,901b2_S1 are all slightly larger than the diffusion of point image spot radius of tested optical system 8.When image space mask 901 adopts Fig. 9 (c) structure, some position, tested optical system two visual fields can be detected in one-shot measurement.

In Fig. 9 (d), image space mask 901 comprises an optical transmission window 901b, the first filtering circular hole 901a1 and the second filtering circular hole 901a2; First filtering circular hole 901a1 is identical with the filtering circular hole 901a in Fig. 9 (a), Fig. 9 (b) with the feature of the second filtering circular hole 901a2; Optical transmission window 901b be can unscreened while through the first output terminal 6C of described desirable wavefront generating unit 6 and the quadrilateral transmission region of the diffusion of point image spot of the second output terminal 6D after the imaging of tested optical system 8.The part of optical transmission window 901b in image space mask 901, the first filtering circular hole 901a1 and the second filtering circular hole 901a2 is transmission region, and other parts are for there being the light tight district of light shield layer.First filtering circular hole 901a1 and the second filtering circular hole 901a2 lays respectively at the optical transmission window 901b left and right sides.Optical transmission window 901b only has 1 edge 901b_S1, and the bee-line between the first filtering circular hole 901a1 and the second filtering circular hole 901a2 and edge 901b_S1 is all slightly larger than the diffusion of point image spot radius of tested optical system 8.When image space mask 901 adopts Fig. 9 (d) structure, some position, tested optical system two visual fields can be detected in one-shot measurement.

In Fig. 9 (e), image space mask 901 comprises an optical transmission window 901b, a filtering circular hole 901a.With Fig. 9 (d) unlike, only have a filtering circular hole 901a, filtering circular hole 901a can be arranged in the position of Fig. 9 (d) first filtering circular hole 901a1, also can be positioned at the position of the second filtering circular hole 901a2; Other features are identical with Fig. 9 (d); When image space mask 901 adopts Fig. 9 (e) structure, one-shot measurement can only detect the unified some position, visual field of tested optical system.

Figure 10 is the structural representation of a point-diffraction interference wave aberration measuring instrument of the present invention embodiment.Light source 1 is the laser instrument that single-mode fiber exports.Optical splitter 2 is fiber couplers.First light intensity and polarization state regulator 3 are made up of adjustable attenuator 301 and Polarization Controller 302, and adjustable attenuator 301 and Polarization Controller 302 all adopt optical fibre device, along light working direction, before adjustable attenuator 301 is connected to Polarization Controller 302; Adjustable attenuator 301 is made up of the optical fiber connected successively, fiber collimating lenses, adjustable diaphragm, fiber coupling lens, optical fiber; Polarization Controller 302 is made up of the optical fiber quarter-wave plate connected successively, optical fiber half-wave plate, optical fiber quarter-wave plate.Phase-shifter 4 adopts the structure shown in Fig. 3 (a).Second light intensity is identical with polarization state regulator 3 with the first light intensity with the structure of polarization state regulator 5.Light path is adjustable, and light path 2A and light path fixed light path 2B is optic fibre light path.Desirable wavefront generating unit 6 adopts structure shown in Fig. 4.Object space minute adjustment platform 7 be there is X, Y, Z tri-Linear-free degree and X θ, Y θ, the sextuple precision displacement table of Z θ tri-rotary freedoms realizes.Tested optical system 8 is micro projection objectives.Image space Wave-front measurement unit 9 adopts structure shown in Fig. 8 (c); Image space mask 901 adopts structure shown in Fig. 9 (b), and optical transmission window 901b adopts the advantage of annular to be to reduce step 2 in test process) aligning difficulty.Image space minute adjustment platform 10 is also the sextuple precision displacement table with X, Y, Z tri-Linear-free degree and X θ, Y θ, Z θ tri-rotary freedoms.Data processing unit 11 stores interferogram, carries out interferogram analysis process to obtain the computing machine of wave aberration.

Figure 11 is the structural representation of point-diffraction interference wave aberration measuring instrument of the present invention second embodiment.Light source 1 is the laser instrument that free space directional light exports.Optical splitter 2 is beam splitter prisms.First light intensity and polarization state regulator 3 are rotary glass sheets being coated with differential declines film at different sector region of only regulating optical power.Phase-shifter 4 adopts the structure shown in Fig. 3 (b).Second light intensity and polarization state regulator 5 are iriss of only regulating optical power.Light path is adjustable, and light path 2A and light path fixed light path 2B is free space light path; Mirror M 1 on light path is adjustable light path 2A and M2, the mirror M 3 on light path fixed light path 2B, M4, M5, M6 are only used for changing the transmission direction of light.Desirable wavefront generating unit 6 adopts structure shown in Fig. 7.Image space Wave-front measurement unit 9 adopts structure shown in Fig. 8 (a); Image space mask 901 adopts structure shown in Fig. 9 (a).Other and Figure 10 first embodiment is identical.

When one-shot measurement only measures a visual field point, utilize the point-diffraction interference wave aberration measuring instrument described in Figure 10 or Figure 11 to detect the method for tested optical system wavefront aberration, it is characterized in that comprising the following steps:

1) mobile object space minute adjustment platform 7, makes the first output terminal 6C of desirable wavefront generating unit 6 be positioned at the position of the visual field point that tested optical system 8 needs are measured;

2) mobile image space minute adjustment platform 10, makes the picture point of the first output terminal 6C of desirable wavefront generating unit 6 aim at the center of the filtering circular hole 901a of image space mask 901, and the picture point of the second output terminal 6D is positioned at the optical transmission window 901b inside of image space mask 901;

3) regulate the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5, the largest light intensity of the interferogram that photoelectric sensor 902 is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor 902, and interference visibility reaches more than 0.6; Phase-shifter 4 and photoelectric sensor 902 repeat phase shift and the interferogram sampling of 4 phase-shift phase pi/2s, and obtain the interferogram that 4 width have phase-shift phase pi/2 each other successively, the light distribution of interferogram is expressed as Ia1 successively, Ia2, Ia3, Ia4; Wrapped phase distribution WR is calculated according to the phase shift interference phase extraction algorithms shown in formula (11) _a, WR _apHASE DISTRIBUTION W is obtained after Phase-un-wrapping _a;

${\mathrm{WR}}_a={\tan }^{-1}\left(\frac{I_{a4}-I_{a2}}{I_{a1}-I_{a3}}\right).---\left(11\right)$

4) step 6) is entered;

6) mobile image space minute adjustment platform 10, carries out fine registration, makes the first output terminal 6C of desirable wavefront generating unit and the picture point of the second output terminal 6D all be positioned at the optical transmission window 901b inside of image space mask 901;

7) regulate the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5, the largest light intensity of the interferogram that photoelectric sensor 902 is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor 902, and interference visibility reaches more than 0.6; Phase-shifter 4 and photoelectric sensor 902 repeat phase shift and the interferogram sampling of 4 phase-shift phase pi/2s, and obtain the interferogram that 4 width have phase-shift phase pi/2 each other successively, the light distribution of interferogram is expressed as Ic1 successively, Ic2, Ic3, Ic4; Wrapped phase distribution WR is calculated according to the phase shift interference phase extraction algorithms shown in formula (12) _c, WR _cpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _c;

${\mathrm{WR}}_c={\tan }^{-1}\left(\frac{I_{c4}-I_{c2}}{I_{c1}-I_{c3}}\right).---\left(12\right)$

8) formula W is utilized ₁=W _a-W _ccalculate the wave aberration W of tested optical system 8 at measured visual field point ₁.

Described phase shift interference phase extraction algorithms represents by the form of arctan function, and the PHASE DISTRIBUTION obtained is truncated the region becoming change within the scope of multiple 2 π, is called wrapped phase; For finally obtaining continuous print phase information, multiple region splicing blocking phase place is launched into continuous phase, and this process is called Phase-un-wrapping.

When one-shot measurement two visual field points, utilize the point-diffraction interference wave aberration measuring instrument described in Figure 10 or Figure 11 to detect the method for tested optical system wavefront aberration, it is characterized in that comprising the following steps:

1) mobile object space minute adjustment platform 7, makes the first output terminal 6C of desirable wavefront generating unit 6 and the second output terminal 6D be positioned at the position of the visual field point that tested optical system 8 needs are measured;

2) mobile image space minute adjustment platform 10, carry out fine registration, the picture point of the first output terminal 6C of desirable wavefront generating unit 6 is aimed at the center of the filtering circular hole 901a of image space mask 901, and the picture point of the second output terminal 6D is positioned at the optical transmission window 901b inside of image space mask 901;

3) regulate the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5, the largest light intensity of the interferogram that photoelectric sensor 902 is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor 902, and interference visibility reaches more than 0.6; Phase-shifter 4 and photoelectric sensor 902 repeat phase shift and the interferogram sampling of 5 phase-shift phase pi/2s, and obtain the interferogram that 5 width have phase-shift phase pi/2 each other successively, the light distribution of interferogram is expressed as Ia1 successively, Ia2, Ia3, Ia4, Ia5; Wrapped phase distribution WR is calculated according to the phase shift interference phase extraction algorithms shown in formula (13) _a, WR _apHASE DISTRIBUTION W is obtained after Phase-un-wrapping _a;

${\mathrm{WR}}_a={\tan }^{-1}\left(\frac{2(I_{a4}-I_{a2})}{I_{a1}-2I_{a3}+I_{a5}}\right).---\left(13\right)$

4) mobile image space minute adjustment platform 10, carry out fine registration, the picture point of the second output terminal 6D of desirable wavefront generating unit 6 is aimed at the center of the filtering circular hole 901a of image space mask 901, and the picture point of the first output terminal 6C is positioned at the optical transmission window 901b inside of image space mask 901;

5) regulate the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5, the largest light intensity of the interferogram that photoelectric sensor 902 is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor 902, and interference visibility reaches more than 0.6; Phase-shifter 4 and photoelectric sensor 902 repeat phase shift and the interferogram sampling of 5 phase-shift phase pi/2s, and obtain the interferogram that 5 width have phase-shift phase pi/2 each other successively, the light distribution of interferogram is expressed as Ib1 successively, Ib2, Ib3, Ib4, Ib5; Wrapped phase distribution WR is calculated according to the phase shift interference phase extraction algorithms shown in formula (14) _b, WR _bpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _b;

${\mathrm{WR}}_b={\tan }^{-1}\left(\frac{2(I_{b4}-I_{b2})}{I_{b1}-2I_{b3}+I_{b5}}\right).---\left(14\right)$

6) mobile image space minute adjustment platform 10, carries out fine registration, makes the first output terminal 6C of desirable wavefront generating unit and the picture point of the second output terminal 6D all be positioned at the optical transmission window 901b inside of image space mask 901;

7) regulate the first light intensity and polarization state regulator 3 and the second light intensity and polarization state regulator 5, the largest light intensity of the interferogram that photoelectric sensor 902 is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor 902, and interference visibility reaches more than 0.6; Phase-shifter 4 and photoelectric sensor 902 repeat phase shift and the interferogram sampling of 5 phase-shift phase pi/2s, and obtain the interferogram that 5 width have phase-shift phase pi/2 each other successively, the light distribution of interferogram is expressed as Ic1 successively, Ic2, Ic3, Ic4, Ic5; Wrapped phase distribution WR is calculated according to the phase shift interference phase extraction algorithms shown in formula (15) _c, WR _cpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _c;

${\mathrm{WR}}_c={\tan }^{-1}\left(\frac{2(I_{c4}-I_{c2})}{I_{c1}-2I_{c3}+I_{c5}}\right).---\left(15\right)$

8) formula W is utilized ₁=W _a-W _ccalculate the wave aberration W of tested optical system 8 at the first visual field, output terminal 6C place point of desirable wavefront generating unit 6 ₁; Utilize formula W ₂=W _c-W _bcalculate the wave aberration W of tested optical system 8 at the second visual field, output terminal 6D place point of desirable wavefront generating unit 6 ₂.

Claims (13)

1. a point-diffraction interference wave aberration measuring instrument, it is characterized in that the formation of this measuring instrument comprises: light source (1), optical splitter (2), first light intensity and polarization state regulator (3), phase-shifter (4), second light intensity and polarization state regulator (5), desirable wavefront generating unit (6), object space minute adjustment platform (7), tested optical system (8), image space Wave-front measurement unit (9), image space minute adjustment platform (10) and data processing unit (11), described image space Wave-front measurement unit (9) is by image space mask (901), photoelectric sensor (902), support (903) is formed, image space mask (901) comprises optical transmission window (901b) and filtering circular hole (901a), described photoelectric sensor (902) comprises a two-dimensional detector (902b), the position relationship of above-mentioned each component is as follows:

The working direction exporting light at described light source (1) is described optical splitter (2), incident light is divided into two-way by this optical splitter (2): a road is the adjustable light path of light path (2A), and another road is light path fixed light path (2B); The adjustable light path of light path (2A) is successively the first light intensity and polarization state regulator (3) and phase-shifter (4), through the adjustable light path of this light path incident light input described in the first input end (6A) of desirable wavefront generating unit (6); Upper placement second light intensity of described light path fixed light path (2B) and polarization state regulator (5), second input end (6B) of the desirable wavefront generating unit (6) described in inputting through the incident light of this light path fixed light path (2B); First output terminal (6C) of this desirable wavefront generating unit (6) and the second output terminal (6D) are positioned at the object plane of described tested optical system (8); This desirable wavefront generating unit (6) is supported and precision positioning by object space minute adjustment platform (7); Described image space Wave-front measurement unit (9) is positioned at the image space of tested optical system (8), the image space mask (901) of image space Wave-front measurement unit (9) is positioned at the image planes of tested optical system (8), and the two-dimensional detector (902b) of photoelectric sensor (902) is positioned at along after light working direction image space mask (901); Image space Wave-front measurement unit (9) is supported and precision positioning by described image space minute adjustment platform (10); The data processing unit (11) described in output signal input of image space Wave-front measurement unit (9).

2. point-diffraction interference wave aberration measuring instrument according to claim 1, it is characterized in that described light source is laser instrument, light emitting diode, super-radiance light emitting diode or monochromator, described light source is the light source that optical fiber exports, or the light source that free space collimation exports.

3. point-diffraction interference wave aberration measuring instrument according to claim 1, is characterized in that described optical splitter is fiber coupler, glass plate that Amici prism or one side are coated with spectro-film.

4. point-diffraction interference wave aberration measuring instrument according to claim 1, it is characterized in that the first described light intensity and polarization state regulator and the second light intensity and polarization state regulator are made up of adjustable attenuator and Polarization Controller, or be made up of a rotatable analyzer; The first described light intensity and the structure of polarization state regulator and the second light intensity and polarization state regulator identical or different.

5. point-diffraction interference wave aberration measuring instrument according to claim 1, it is characterized in that described phase-shifter is the device changing light path light path: comprise the single-mode fiber ring be wrapped on column piezoelectric ceramics, by changing the driving voltage of column piezoelectric ceramics, stretching single-mode fiber, change light path; The variable optical delay line of beam splitter prism, catoptron and piezoelectric ceramics composition; Or drive catoptron or prism motion to change light path by piezoelectric ceramics.

6. point-diffraction interference wave aberration measuring instrument according to claim 1, it is characterized in that described desirable wavefront generating unit is that to convert within the scope of the object-side numerical aperture of tested optical system be standard ball ground roll by the light from its first input end and the input of the second input end, and respectively from the optical module that its first output terminal or the second output terminal export, the centre distance s between the first output terminal of desirable wavefront generating unit and the second output terminal _obe greater than the enlargement factor of diameter divided by tested optical system of tested optical system diffusion of point image spot;

Described desirable wavefront generating unit is made up of the first optical fiber and the second optical fiber; The input end of the first optical fiber is the first input end of desirable wavefront generating unit, and the output terminal of the first optical fiber is the first output terminal of desirable wavefront generating unit; The input end of the second optical fiber is the second input end of desirable wavefront generating unit, and the output terminal of the second optical fiber is the second output terminal of desirable wavefront generating unit; The first described optical fiber and the second optical fiber are single-mode fiber or polarization maintaining optical fibre; The output terminal core diameter Φ of the first optical fiber and the second optical fiber _fbe less than the object space resolution of diffraction of described tested optical system, meet Φ _f< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system;

Or described desirable wavefront generating unit is made up of the 3rd optical fiber, the 4th optical fiber, imaging lens group and object plane mask; The input end of the 3rd optical fiber is the first input end of desirable wavefront generating unit, and the output terminal of the 3rd optical fiber is positioned at the object plane of imaging lens group; The input end of the 4th optical fiber is the second input end of desirable wavefront generating unit, and the output terminal of the 4th optical fiber is positioned at the object plane of imaging lens group; Object plane mask is positioned at the image planes of imaging lens group; Object plane mask there are the first circular hole and the second circular hole; First circular hole is the first output terminal of desirable wavefront generating unit, and the second circular hole is the second output terminal of desirable wavefront generating unit; The output terminal of the 3rd optical fiber is imaged on the second circular hole through imaging lens group, and the output terminal of the 4th optical fiber is imaged on the first circular hole through imaging lens group; 3rd optical fiber and the 4th optical fiber are single-mode fiber or polarization maintaining optical fibre; The diameter of phi o of the first circular hole and the second circular hole is less than the object space resolution of diffraction of described tested optical system, and meet Φ o< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system;

Or described desirable wavefront generating unit is made up of the first catoptron, the second catoptron, focus lamp group, object plane mask; First light beam of collimation and the second light beam are respectively from first input end, the second input end input of desirable wavefront generating unit; Along the first light beam working direction, successively through the first catoptron, focus lamp group and object plane mask; Along the second light beam working direction, successively through the second catoptron, focus lamp group and object plane mask; Object plane mask is positioned on the back focal plane of focus lamp group; Object plane mask there are the first circular hole and the second circular hole; The first circular hole on object plane mask and the second round hole part are divided into photic zone, and other parts are light tight district; First circular hole is the first output terminal of desirable wavefront generating unit, and the second circular hole is the second output terminal of desirable wavefront generating unit; The diameter of phi o of the first circular hole and the second circular hole is less than the object space resolution of diffraction of described tested optical system, and meet Φ o< λ/(2NAo), wherein λ is optical source wavelength, and NAo is the object-side numerical aperture of tested optical system; Have an angle between the first described catoptron and the second catoptron, make the first light beam focus on the first output terminal by focus lamp group, the second light beam focuses on the second output terminal by focus lamp group.

7. point-diffraction interference wave aberration measuring instrument according to claim 1, is characterized in that described image space mask is positioned at the image planes of tested optical system; Image space mask comprises optical transmission window and filtering circular hole; Filtering circular hole is the printing opacity aperture that diameter of phi i is less than the image space resolution of diffraction of described tested optical system, meet Φ i< λ/(2NAi), wherein λ is optical source wavelength, NAi is the image-side numerical aperture of tested optical system, described optical transmission window be can unscreened while through the transmission region of the quadrilateral of the first output terminal of described desirable wavefront generating unit and the diffusion of point image spot of the second output terminal after tested optical system imaging, annular or other shapes.

8. point-diffraction interference wave aberration measuring instrument according to claim 1, it is characterized in that described photoelectric sensor is that two-dimensional detector or transform optics mirror group and two-dimensional detector are formed, the photoelectric sensor be made up of transform optics mirror group and two-dimensional detector, image space mask is positioned at the front focal plane of described transform optics mirror group, and described two-dimensional detector is positioned at the back focal plane of transform optics mirror group.

9. point-diffraction interference wave aberration measuring instrument according to claim 8, is characterized in that described transform optics mirror group is can simple lens, lens combination, the catoptron group of imaging.

10. point-diffraction interference wave aberration measuring instrument according to claim 8, is characterized in that described two-dimensional detector is CCD, CMOS, or photodiode array.

11. point-diffraction interference wave aberration measuring instruments according to claim 1, is characterized in that described data processing unit is storage interferogram, carries out interferogram analysis process to obtain computing machine or the embedded system of wave aberration.

12. utilize the point-diffraction interference wave aberration measuring instrument described in claim 1 to detect the method for tested optical system wavefront aberration, it is characterized in that the method comprises the following steps:

1) mobile object space minute adjustment platform, makes the first output terminal of desirable wavefront generating unit or/and the second output terminal is positioned at the position that tested optical system needs the visual field point measured;

2) if the first output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, mobile image space minute adjustment platform, carry out fine registration, the picture point of the first output terminal of desirable wavefront generating unit is aimed at the center of the filtering circular hole of image space mask, the picture point of the second output terminal is positioned at the optical transmission window inside of image space mask, then enters step 3); If the first output terminal position of desirable wavefront generating unit is not the position that tested optical system needs the visual field point measured, directly enter step 4);

3) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of interferogram is expressed as Ia1 successively, Ia2,, Iam, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _a, WR _apHASE DISTRIBUTION W is obtained after Phase-un-wrapping _a;

4) if the second output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, mobile image space minute adjustment platform, carry out fine registration, the picture point of the second output terminal of desirable wavefront generating unit is aimed at the center of the filtering circular hole of image space mask, the picture point of the first output terminal is positioned at the optical transmission window inside of image space mask, then enters step 5); If the second output terminal position of desirable wavefront generating unit is not the position that tested optical system needs the visual field point measured, directly enter step 6);

5) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of this interferogram is expressed as Ib1 successively, Ib2,, Ibm, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _b, WR _bpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _b;

6) carry out fine registration, make the picture point of two output terminals of desirable wavefront generating unit all be positioned at the optical transmission window inside of image space mask;

7) regulate the first light intensity and polarization state regulator and the second light intensity and polarization state regulator, the intensity of the interferogram that photoelectric sensor is collected reaches 0.6 ~ 0.9 of the saturated light intensity of photoelectric sensor, and interference visibility reaches more than 0.6; Carried out the phase shift of phase-shift phase δ by described phase-shifter, described photoelectric sensor gathers interferogram, Repeated m time, obtain the interferogram that a group has phase-shift phase δ each other successively, the light distribution of this interferogram is expressed as Ic1 successively, Ic2,, Icm, m are interferogram quantity; Wrapped phase distribution WR is calculated according to adopted phase shift interference phase extraction algorithms _c, WR _cpHASE DISTRIBUTION W is obtained after Phase-un-wrapping _c;

8) if the first output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, then formula W is utilized ₁=W _a-W _ccalculate the wave aberration W of tested optical system at this visual field point ₁; If the second output terminal position of desirable wavefront generating unit is the position that tested optical system needs the visual field point measured, then utilize formula W ₂=W _c-W _bcalculate the wave aberration W of this visual field point ₂.

The method of the tested optical system wavefront aberration of 13. detection according to claim 12, is characterized in that described phase shift interference phase extraction algorithms is the computing method of the wrapped phase distribution that the light distribution calculation interferogram of the interferogram successively each other by a group with phase-shift phase δ is carried;

When phase-shift phase δ equals pi/2, when interferogram quantity m equals 3, described phase shift interference phase extraction algorithms is calculated as follows:

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{I_{*3}-I_{*2}}{I_{*1}-I_{*2}}\right);---\left(1\right)$

When phase-shift phase δ equals pi/2, when interferogram quantity m equals 4, described phase shift interference phase extraction algorithms as shown in the formula:

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{I_{*4}-I_{*2}}{I_{*1}-I_{*3}}\right);---\left(2\right)$

When phase-shift phase δ equals pi/2, when interferogram quantity m equals 5, described phase shift interference phase extraction algorithms as shown in the formula:

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{2(I_{*4}-I_{*2})}{I_{*1}-{2I}_{*3}+I_{*5}}\right);---\left(3\right)$

When phase-shift phase δ equals 2 π/m, during interferogram quantity m >=3, described phase shift interference phase extraction algorithms is as shown in the formula shown in (4)

${\mathrm{WR}}_{*}={\tan }^{-1}\left(\frac{-\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{I}_{*i}\sin (i\&times;\mathrm{\&delta;})}{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{I}_{*i}\cos (i\&times;\mathrm{\&delta;})}\right);---\left(4\right)$

In formula (1) ~ (4), * represents a, b or c.