CN104165599A - Aspheric surface non-contact type measuring system and method for deflection workpieces - Google Patents

Abstract

The invention provides an aspheric surface non-contact type measuring system for deflection workpieces. The aspheric surface non-contact type measuring system comprises a non-contact type optical profilometer probe, a profilometer lifting and adjusting mechanism, a precise three-dimensional displacement table, a digital display inclinometer, a two-dimensional deflection table, a base and a computer system. The non-contact type optical profilometer probe is fixed on the profilometer lifting and adjusting mechanism. The precise three-dimensional displacement table is fixed on the two-dimensional deflection table and is used for bearing, horizontal moving and positioning of a measured piece. The digital display inclinometer is fixed on the two-dimensional deflection table and is used for measuring the deflection angle of the two-dimensional deflection table. The two-dimensional deflection table is fixed on the base and is used for achieving deflection of the measured piece through deflection. The computer system is in data connection with the non-contact type optical profilometer probe, the precise three-dimensional displacement table and the digital display inclinometer to receive the face data of measuring points and the horizontal displacement data and the deflection angle of a measured piece, and the face data, the horizontal displacement data and the deflection angle are processed to achieve aspheric surface face recovery. The invention further relates to an aspheric surface non-contact type measuring method for the deflection workpieces.

Description

The aspheric contactless measuring system of beat workpiece and method

Technical field

The present invention relates to interference of light precision measurement field, in particular to the aspheric contactless measuring system of a kind of beat workpiece and method.

Background technology

Aspherical optical element is the optical element that surface configuration departs from sphere, than conventional planar, spherical optics element, there is larger degree of freedom and dirigibility, and shape is various, thereby can effectively proofread and correct various aberrations, improve picture element, and reduce the quantity of the required optical element of system, reduce system physical dimension, mitigation system weight etc.Along with the development of modern science and technology, optical aspherical surface, due to its excellent optical property, is having more and more important widespread use aspect the key technology areas such as space camera, large telescope and infrared seeker and photovoltaic.Yet the high-quality aspherical mirror machining of high precision and detection technique are difficult points always, particularly aperture aspherical is due to the increase of its rise, produced the contradiction between wide-measuring range and measuring accuracy, processing and detection technique become the bottleneck of the further widespread use of restriction aspheric surface.

Traditional aspheric surface detection method comprises contact and contactless two kinds.

Contact type measurement generally drives probe to carry out scanning survey to optical surface by mechanical measurement arm, the swing-arm profilometry of National University of Defense technology's independent research that more representative is (Jia Lide for example, Zheng Ziwen, Dai Yifan, Li Shengyi. the principle of swing arm aspherical profile instrument and test [J]. optical precision engineering, 2007,15 (4): 499-504), yet contact type measurement adopts simple scan, and efficiency is lower, and the easy lesion element surface of popping one's head in.

Unified interferometric method is a kind of conventional non-contact measurement mode, its general employing and to be measured the interferometer that bore is suitable, by the striped forming from two beam interferences of reference mirror and test mirrors is respectively resolved to the face shape information that obtains test mirrors, but expensive, and make specific offset lens comparatively difficulty (for example Guo Ren is intelligent. near infrared heavy caliber phase-shifting interferometer via wavelength tuning gordian technique and application [D]. Institutes Of Technology Of Nanjing 2008).In addition, another contactless measurement has also been proposed in prior art, by measuring the overlapping sub-aperture of a series of phase mutuals, splicing obtains unified shape of measured lens, but sub-aperture stitching interferometer method easily produces cumulative errors in splicing, affect measuring accuracy (for example old bravely kind. the method for geometry research [D] of aspheric aperture splicing interferometry. the National University of Defense Technology 2006).

Summary of the invention

For defect of the prior art, the invention provides the aspheric contactless measuring system of a kind of beat workpiece and method, be intended to solve aspheric surface detection difficult problem, and measuring accuracy is high, during measurement, without reference surface shape, lesion element is not surperficial.

Above-mentioned purpose of the present invention realizes by the technical characterictic of independent claims, and dependent claims develops the technical characterictic of independent claims with alternative or favourable mode.

For reaching above-mentioned purpose, a first aspect of the present invention discloses the aspheric contactless measuring system of a kind of beat workpiece, comprise: non-contact optical profiler probe, contourgraph lift adjustment mechanism, accurate three-D displacement platform, digital display inclinometer, two-dimentional beat platform, base and a computer system, wherein:

Described non-contact optical profiler probe is fixed in contourgraph lift adjustment mechanism;

Described accurate three-D displacement platform is fixed on described two-dimentional beat platform, and for realizing to the carrying of measured piece with to the transverse shifting of measured object and location;

Described digital display inclinometer is fixed on described two-dimentional beat platform, and for measuring the deflection angle of two-dimentional beat platform;

Described two-dimentional beat platform is fixed on described base, and for popping one's head in over against described non-contact optical profiler by realize the aspheric surface measured point of measured piece around axle beat;

Described computer system via a communication link pop one's head in described non-contact optical profiler, accurate three-D displacement platform, digital display inclinometer data be connected, receive respectively transversal displacement data and the deflection angle data of measurement point face graphic data, measured piece, and process and realize aspheric shape recovery.

According to another object of the present invention, a kind of aspheric contactless measurement of beat workpiece that utilizes aforementioned measuring system to realize is disclosed, comprise the following steps:

Step 1, measured piece is positioned on an accurate three-D displacement platform, adjusts non-contact optical profiler probe and make it over against the aspheric surface Rotational Symmetry center of measured piece, measure place, summit face shape;

Step 2, by mobile described accurate three-D displacement platform, make measured piece transverse shifting certain distance, adjust two-dimentional beat platform, make non-contact optical profiler probe over against measured point aspheric surface beat to the correct position of measured piece, and record deflection angle by digital display inclinometer, utilize the face graphic data of aforementioned this measurement point of non-contact optical profiler probe measurement, and import described computer system into together with aforementioned deflection angle data and transversal displacement data simultaneously;

Step 3, repetition abovementioned steps 2, to measure the face graphic data through a plurality of measurement points on a transversal at described aspheric Rotational Symmetry center, wherein each measurement point is a sub-aperture, then utilize aforementioned computer system to adopt least square sphere fitting algorithm to extract the curvature value c of central spot to the face graphic data in every sub-aperture, the inverse that this curvature value c is sphere curvature radius, can obtain one group of curvature value equation X～c corresponding with described horizontal ordinate thus;

Step 4, for each same measurement point, according to its transverse translation with respect to Rotational Symmetry center distance and at the deflection angle of the two-dimentional beat platform of this measurement point, according to following coordinate compensation model, carry out coordinate compensation, the curvature value X corresponding with horizontal ordinate after being compensated _c～c:

Making each transverse translation distance of measured piece in measuring process is t, and while measuring for the n time, the horizontal ordinate X of measured piece is not nt, but the X being determined by following formula _c:

$\left\{\begin{array}{c}f({\mathrm{\λ}}_i,X_c)=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ f^{\′}({\mathrm{\λ}}_i,X_c)=\tan \mathrm{\α}\end{array}\right.---\left(1\right)$

In formula, f (λ _i, X _c) be aspherical equation, f ' (λ _i, X _c) be aspherical equation f (λ _i, X _c) first order derivative, α be while measuring for the n time two dimension beat platform with respect to total deflection angle of its reference position, λ _ifor asphericity coefficient;

The corresponding curvature value equation X of horizontal ordinate after can being compensated thus _c～c; And

Step 5, at aspherical equation f (λ _i, X _c) under definite prerequisite, according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, by least square fitting, simulate asphericity coefficient λ _ithereby the aspheric surface of realizing measured piece recovers.

From the above technical solution of the present invention shows that, beneficial effect of the present invention is:

1) than traditional contact type measurement method, the solution of the present invention adopts interference of light method, for non-contact measurement can not produce damage to measured piece;

2), than traditional contactless unified measurement, the solution of the present invention, without making specific compensating glass, also without expensive aperture interferometer, only needs common noncontact contourgraph to measure;

3) than traditional contactless stitching interferometry, the present invention, without complicated stitching algorithm, can not produce cumulative errors, and measuring accuracy is high.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the aspheric contactless measuring system of an embodiment of the present invention beat workpiece.

Fig. 2 is the realization flow schematic diagram that the measuring system of Fig. 1 embodiment is carried out the aspheric non-cpntact measurement of beat workpiece.

Embodiment

In order more to understand technology contents of the present invention, especially exemplified by specific embodiment and coordinate appended graphic being described as follows.

In conjunction with Fig. 1, according to preferred embodiment of the present invention, the aspheric contactless measuring system of a kind of beat workpiece, it comprises: non-contact optical profiler probe 1, contourgraph lift adjustment mechanism 2, accurate three-D displacement platform 4, digital display inclinometer 5, two-dimentional beat platform 6, base 7 and a computer system 8, as shown in Figure 1, wherein:

Non-contact optical profiler probe 1 is fixed in contourgraph lift adjustment mechanism 2;

Accurate three-D displacement platform 4 is fixed on described two-dimentional beat platform 6, and for realizing to the carrying of measured piece 3 with to the transverse shifting of measured object 3 and location;

Digital display inclinometer 5 is fixed on described two-dimentional beat platform 6, and for measuring the deflection angle of two-dimentional beat platform 6;

Two dimension beat platform 6 is fixed on described base 7, and for popping one's head in for 1 (comprising horizontal and vertical deflection) over against described non-contact optical profiler by realize the aspheric surface measured point of measured piece 3 around axle beat;

Computer system 8 is connected with described non-contact optical profiler probe 1, accurate three-D displacement platform 4, digital display inclinometer 5 data via a communication link 9, receive respectively transversal displacement data and the deflection angle data of measurement point face graphic data, measured piece 3, and process and realize aspheric shape recovery.

In the present embodiment, utilize aforesaid contactless measuring system to detect the aspheric surface of measured piece 3, face graphic data in conjunction with a plurality of measurement points on a transversal at the aspheric surface Rotational Symmetry center of measured piece, adopt least square sphere fitting algorithm to extract the curvature value c of central spot, the inverse that this curvature value c is sphere curvature radius, can obtain thus one group of curvature value equation X～c corresponding with horizontal ordinate X, thereby carry out matching, realize the recovery of face shape.

In the present embodiment, realize the high-acruracy survey of optical element by optical interference means, as preferred embodiment, aforementioned non-contact optical profiler probe 1 adopts the optic probe of white light interference microscope veeco NT9100.This interference of light microscope is company produces.

Non-contact optical profiler probe 1 vertically clamps by clamping device, its gauge head is over against surface to be measured, be non-contact optical profiler probe 1 and the 3 one-tenth vertical distribution of measured piece that are placed on accurate three-D displacement platform 4, the coordinate information of optical component surface shape information and correspondence is from computer system.

Be fixed on the two-dimentional beat platform 6 on described base 7, for realizing the horizontal and vertical two direction beats of measured piece 3, when measurement has certain steepness surperficial, by beat platform 6, in the adjustment of both direction, make to treat that 1 one-tenth of side and optic probe are vertical, so that interference fringe can be resolved.

Aforesaid accurate three-D displacement platform 4, can be around its vertical axis rotation, and through accurate angular coding, precision reaches submicrosecond magnitude, makes the different transversals at measured piece 3 over-rotation centers be able to measured.

Aforesaid communication link 9, can be in wire communication link or wireless communication link a kind of.Wire communication link, the communication link for example building by usb data line.Wireless communication link, the communication link for example building by wireless communication module (Wifi module, bluetooth module, infrared communication module, 3G module).

In the present embodiment, as preferred scheme, described computer system 8 adopts following algorithm to realize aspheric shape recovery: the face graphic data to a plurality of measurement points on a transversal at the aspheric surface Rotational Symmetry center of described measured piece, adopt least square sphere fitting algorithm to extract the curvature value c of central spot, the inverse that this curvature value c is sphere curvature radius, can obtain one group of curvature value equation X～c corresponding with horizontal ordinate X thus;

Making each transverse translation distance of measured piece 3 in measuring process is t, and while measuring for the n time, the horizontal ordinate X of measured piece 3 is not nt, but the X being determined by following formula _c:

$\left\{\begin{array}{c}f({\mathrm{\λ}}_i,X_c)=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ f^{\′}({\mathrm{\λ}}_i,X_c)=\tan \mathrm{\α}\end{array}\right.---\left(1\right)$

In formula, f (λ _i, X _c) be aspherical equation, f ' (λ _i, X _c) be aspherical equation f (λ _i, X _c) first order derivative, α be while measuring for the n time two dimension beat platform 6 with respect to total deflection angle of its reference position, λ _ifor asphericity coefficient;

The corresponding curvature value equation X of horizontal ordinate after can being compensated thus _c～c;

Then, at f (λ _i, X _c) under definite prerequisite, according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, by least square fitting, simulate asphericity coefficient λ _ithereby the aspheric surface of realizing measured piece recovers.

The being tested surface parabola (being aspheric surface) of measured piece 3 of take is below example, and its aspherical equation is known, and is:

f(λ _i，X _c)＝λX _c ²；

By its substitution aforementioned formula (1), can obtain:

$\left\{\begin{array}{c}\mathrm{\λ}{X_c}^2=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ 2\mathrm{\λ}{X}_c=\tan \mathrm{\α}\end{array}\right.---\left(2\right)$

By above-mentioned formula, can solve one group through the abscissa value X of over-compensation _c:

$X_c=\frac{-1-\sqrt{1+4\mathrm{nt\λ}\sin \mathrm{\α}(1+{\tan }^2\mathrm{\α})}}{2\mathrm{\λ}\tan \mathrm{\α}}---\left(3\right)$

By above-mentioned formula, obtain one group of accurate X _cthe value of～c.

The computing formula of curvature is as follows:

$c=\frac{f^{\′\′}({\mathrm{\λ}}_i,X_c)}{(1+f^{\′}({\mathrm{\λ}}_i,X_c)^2)^(3/2)}=\frac{2\mathrm{\λ}}{(1+4{\mathrm{\λ}}^2{X_c}^2)^(3/2)}---\left(4\right)$

Wherein:

First order derivative is: $f^{\′}({\mathrm{\λ}}_i,X_c)=\frac{\∂f}{\∂X}=2\mathrm{\λ}{X}_c$

Second derivative is: $f^{\′\′}({\mathrm{\λ}}_i,X_c)=\frac{{\∂}^{2}f}{{\∂}^{2}X}=2\mathrm{\λ}$

As exemplary illustration, under the definite prerequisite of aforementioned aspherical equation, i.e. f (λ _i, X _c)=λ X _c ², according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, can to () formula, carry out matching by least square fitting, simulate asphericity coefficient λ, thereby realize the aspheric surface recovery of measured piece.

It is worth mentioning that, when doing aspheric surface detection, its aspherical equation provides conventionally, and the asphericity coefficient that only need to obtain wherein can be realized the recovery of face shape.

The implementation step that has provided the aspheric contactless measurement of beat workpiece of the contactless measuring system realization that utilizes earlier figures 1 below, wherein, shown in Fig. 2, this contactless measurement comprises the following steps:

Step 1, measured piece 3 is positioned on an accurate three-D displacement platform 4, adjusts non-contact optical profiler probe 1 and make it over against the aspheric surface Rotational Symmetry center of measured piece, measure place, summit face shape;

Step 2, by mobile described accurate three-D displacement platform 4, make measured piece 3 transverse shifting certain distances, adjust two-dimentional beat platform 6, make non-contact optical profiler probe 1 over against measured point aspheric surface beat to the correct position of measured piece 5, and record deflection angle by digital display inclinometer 5, utilize aforementioned non-contact optical profiler probe 1 to measure the face graphic data of this measurement point, and import described computer system 8 into together with aforementioned deflection angle data and transversal displacement data simultaneously;

Step 3, repetition abovementioned steps 2, to measure the face graphic data through a plurality of measurement points on a transversal at described aspheric Rotational Symmetry center, wherein each measurement point is a sub-aperture, then utilize aforementioned computer system to adopt least square sphere fitting algorithm to extract the curvature value c of central spot to the face graphic data in every sub-aperture, the inverse that this curvature value c is sphere curvature radius, can obtain one group of curvature value equation X～c corresponding with described horizontal ordinate thus;

Step 4, for each same measurement point, according to its transverse translation with respect to Rotational Symmetry center distance and at the deflection angle of the two-dimentional beat platform 6 of this measurement point, according to following coordinate compensation model, carry out coordinate compensation, the curvature value X corresponding with horizontal ordinate after being compensated _c～c:

Making each transverse translation distance of measured piece 3 in measuring process is t, and while measuring for the n time, the horizontal ordinate X of measured piece 3 is not nt, but the X being determined by following formula _c:

$\left\{\begin{array}{c}f({\mathrm{\λ}}_i,X_c)=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ f^{\′}({\mathrm{\λ}}_i,X_c)=\tan \mathrm{\α}\end{array}\right.---\left(1\right)$

In formula, f (λ _i, X _c) be aspherical equation, f ' (λ _i, X _c) be aspherical equation f (λ _i, X _c) first order derivative, α be while measuring for the n time two dimension beat platform 6 with respect to total deflection angle of its reference position, λ _ifor asphericity coefficient;

The corresponding curvature value equation X of horizontal ordinate after can being compensated thus _c～c; And

Step 5, at aspherical equation f (λ _i, X _c) under definite prerequisite, according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, by least square fitting, simulate asphericity coefficient λ _ithereby the aspheric surface of realizing measured piece recovers.

Although the present invention discloses as above with preferred embodiment, so it is not in order to limit the present invention.Persond having ordinary knowledge in the technical field of the present invention, without departing from the spirit and scope of the present invention, when being used for a variety of modifications and variations.Therefore, protection scope of the present invention is when being as the criterion depending on claims person of defining.

Claims (4)

1. the aspheric contactless measuring system of beat workpiece, it is characterized in that, comprise: non-contact optical profiler probe (1), contourgraph lift adjustment mechanism (2), accurate three-D displacement platform (4), digital display inclinometer (5), two-dimentional beat platform (6), base (7) and a computer system (8), wherein:

Described non-contact optical profiler probe (1) is fixed in contourgraph lift adjustment mechanism (2);

It is upper that described accurate three-D displacement platform (4) is fixed on described two-dimentional beat platform (6), and for realizing the carrying of measured piece (3) and transverse shifting and location to measured object (3);

It is upper that described two-dimentional beat platform (6) is fixed on described base (7), and for the aspheric surface measured point by realize measured piece (3) around axle beat over against described non-contact optical profiler pop one's head in (1);

It is upper that described digital display inclinometer (5) is fixed on described two-dimentional beat platform (6), and for measuring the deflection angle of two-dimentional beat platform (6);

Described computer system (8) via a communication link (9) pop one's head in (1) with described non-contact optical profiler, accurate three-D displacement platform (4), digital display inclinometer (5) data be connected, receive respectively transversal displacement data and the deflection angle data of measurement point face graphic data, measured piece (3), and process and realize aspheric shape recovery.

2. the aspheric contactless measuring system of beat workpiece according to claim 1, is characterized in that, described non-contact optical profiler probe (1) adopts the optic probe of white light interference microscope veeco NT9100.

3. the aspheric contactless measuring system of beat workpiece according to claim 1, it is characterized in that, described computer system adopts following algorithm to realize aspheric shape recovery: the face graphic data to a plurality of measurement points on a transversal at the aspheric surface Rotational Symmetry center of described measured piece, adopt least square sphere fitting algorithm to extract the curvature value c of central spot, the inverse that this curvature value c is sphere curvature radius, can obtain one group of curvature value equation X～c corresponding with horizontal ordinate X thus;

Making each transverse translation distance of measured piece in measuring process (3) is t, and while measuring for the n time, the horizontal ordinate X of measured piece (3) is not nt, but the X being determined by following formula _c:

$\left\{\begin{array}{c}f({\mathrm{\λ}}_i,X_c)=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ f^{\′}({\mathrm{\λ}}_i,X_c)=\tan \mathrm{\α}\end{array}\right.---\left(1\right)$

In formula, f (λ _i, X _c) be aspherical equation, f ' (λ _i, X _c) be aspherical equation f (λ _i, X _c) first order derivative, α be while measuring for the n time two dimension beat platform (6) with respect to total deflection angle of its reference position, λ _ifor asphericity coefficient;

The corresponding curvature value equation X of horizontal ordinate after can being compensated thus _c～c;

Then, at f (λ _i, X _c) under definite prerequisite, according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, by least square fitting, simulate asphericity coefficient λ _ithereby the aspheric surface of realizing measured piece recovers.

4. utilize the aspheric contactless measurement of beat workpiece that the aspheric contactless measuring system of beat workpiece is realized described in aforementioned claim 1, it is characterized in that, comprise the following steps:

Step 1, that measured piece (3) is positioned over to an accurate three-D displacement platform (4) is upper, adjusts non-contact optical profiler probe (1) and makes it over against the aspheric surface Rotational Symmetry center of measured piece, measures place, summit face shape;

Step 2, by mobile described accurate three-D displacement platform (4), make measured piece (3) transverse shifting certain distance, adjust two-dimentional beat platform (6), make non-contact optical profiler probe (1) over against measured point aspheric surface beat to the correct position of measured piece (3), and record deflection angle by digital display inclinometer (5), utilize aforementioned non-contact optical profiler probe (1) to measure the face graphic data of this measurement point, and import described computer system (8) into together with aforementioned deflection angle data and transversal displacement data simultaneously;

Step 3, repetition abovementioned steps 2, to measure the face graphic data through a plurality of measurement points on a transversal at described aspheric Rotational Symmetry center, wherein each measurement point is a sub-aperture, then utilize aforementioned computer system to adopt least square sphere fitting algorithm to extract the curvature value c of central spot to the face graphic data in every sub-aperture, the inverse that this curvature value c is sphere curvature radius, can obtain one group of curvature value equation X～c corresponding with described horizontal ordinate thus;

Step 4, for each same measurement point, according to its transverse translation with respect to Rotational Symmetry center distance and at the deflection angle of the two-dimentional beat platform (6) of this measurement point, according to following coordinate compensation model, carry out coordinate compensation, the curvature value X corresponding with horizontal ordinate after being compensated _c～c:

Making each transverse translation distance of measured piece in measuring process (3) is t, and while measuring for the n time, the horizontal ordinate X of measured piece (3) is not nt, but the X being determined by following formula _c:

$\left\{\begin{array}{c}f({\mathrm{\λ}}_i,X_c)=\frac{\mathrm{nt}\cos \mathrm{\α}-X_c}{\sin \mathrm{\α}}\cos \mathrm{\α}+\mathrm{nt}\sin \mathrm{\α}\\ f^{\′}({\mathrm{\λ}}_i,X_c)=\tan \mathrm{\α}\end{array}\right.---\left(1\right)$

In formula, f (λ _i, X _c) be aspherical equation, f ' (λ _i, X _c) be aspherical equation f (λ _i, X _c) first order derivative, α be while measuring for the n time two dimension beat platform (6) with respect to total deflection angle of its reference position, λ _ifor asphericity coefficient;

The corresponding curvature value equation X of horizontal ordinate after can being compensated thus _c～c; And

Step 5, at aspherical equation f (λ _i, X _c) under definite prerequisite, according to the curvature value c at the different measuring point place of measuring on a transversal and corresponding lateral coordinates value X _c, by least square fitting, simulate asphericity coefficient λ _ithereby the aspheric surface of realizing measured piece recovers.