CN102901463A - Measurement device and measurement method for axicon surface shape - Google Patents

Abstract

The invention discloses a measurement device and a measurement method for an axicon surface shape. The device consists of a phase-shifting interferometer, a plane standard mirror, a focusing lens and a plane reflecting mirror; the position relation is that the plane standard mirror, the focusing lens and the plane reflecting mirror are arranged along the forward direction of an outgoing beam of the phase-shifting interferometer in sequence; and a socket for an axicon to be detected is formed between the plane standard mirror and the focusing lens. The device has a simple structure; and the measurement method is convenient to operate.

Description

The measurement mechanism of axial cone mirror surface-shaped and measuring method

Technical field

The present invention relates to optical detection, particularly a kind of measurement mechanism of axial cone mirror surface-shaped and measuring method.

Technical background

The axial cone mirror is that a focal line is along the Rotational Symmetry optical element of optical axis direction, because the characteristic of its long depth of focus and narrow transverse width, it is widely used in the aspects such as laser beam reshaping, laser drill technology, optical detection, laser resonator, this has just proposed strict requirement to the surface figure accuracy of axial cone mirror, so need an accurate method that its face shape is measured.

Technology [1] (David Kupka formerly, Philip Schlup, and Randy A.Bartels, " Self-referencedinterferometry for the characterization of axicon lens quality ", Appl.Opt.47 (9): 1200-1205 (2008) .) be used for a simple interferometer of axial cone mirror feature measurement.Interfere by the light wave of measured axis axicon lens and the reference light wave of conllinear, utilize the cylindrical symmetry self-reference interference figure that produces to obtain the distortion of measured axis cone mirror surface-shaped.The method need to utilize the rotation of catoptron to adjust reference beam with respect to the inclination of measuring beam, and they are interfered, and therefrom solves the face shape information of axial cone mirror, and the method can only be surveyed the face shape of large cone angle axial cone mirror simultaneously.

Technology [2] (Jun Ma formerly, Christof Pruss, Matthias, et al. " Axicon metrology using highline density computer-generated Holograms ", Proc.SPIE.8082,1-11 (2011) .) by means of the zero testing of interferometer, utilize a zero-bit optical element---computed hologram provides high-precision system evaluation to cone angle and the face shape error of conical mirror.The method at first needs interferometer is calibrated, and secondly need to move axially conical mirror to be measured and the circumference rotation.

Summary of the invention

The object of the present invention is to provide a kind of measurement mechanism and measuring method of axial cone mirror surface-shaped.These apparatus and method have simple in structure, are easy to the advantages such as measurement.

Technical solution of the present invention is as follows:

A kind of measurement mechanism of axial cone mirror surface-shaped, its characteristics are that this device is comprised of phase-shifting interferometer, plane standard mirror, condenser lens and plane mirror, its position relationship is: be described plane standard mirror, condenser lens and plane mirror successively along described phase-shifting interferometer outgoing beam working direction, the socket of axial cone mirror to be measured is set between described plane standard mirror and condenser lens.

Utilize the measurement mechanism of above-mentioned axial cone mirror surface-shaped to carry out the measuring method of axial cone mirror surface-shaped, its characteristics are that the method comprises the steps:

1. insert axial cone mirror to be measured at the plane standard mirror of the parallel beam direction of phase-shifting interferometer output and the socket of the axial cone mirror to be measured between the condenser lens, the conical surface of described axial cone mirror to be measured is towards the light direction of phase-shifting interferometer;

2. adjust light path: the parallel beam of described phase-shifting interferometer outgoing forms parallel measuring beam through described plane standard mirror, and the light beam that returns through described plane standard mirror forms reference beam; The parallel plane of adjusting described plane standard mirror is vertical with described parallel beam; The plane of adjusting described axial cone mirror to be measured is vertical with measuring beam, guarantees that simultaneously the axis of described axial cone mirror overlaps with the axis of phase-shifting interferometer outgoing beam; Adjust described condenser lens vertical with measuring beam, guarantee that simultaneously the optical axis of described condenser lens overlaps with the axis of phase-shifting interferometer outgoing beam; The plane of adjusting described plane mirror is vertical with optical axis;

3. described measuring beam sees through described axial cone mirror and incides described condenser lens, through described condenser lens light beam is converged on the described plane mirror, then return through described plane mirror reflection, the reference beam that the measuring beam that this returns and plane standard mirror return produces interferes;

4. the distance of adjusting between described condenser lens and the axial cone mirror to be measured obtains complete clearly interference fringe, utilizes described phase-shifting interferometer to detect interference fringe, namely obtains the face shape information of described axial cone mirror.

Described axial cone mirror to be measured is convex surface axial cone mirror or concave surface axial cone mirror.

Compare with technology formerly, technique effect of the present invention is as follows:

1. the present invention can realize that the face shape of the axial cone mirror of any cone angle is detected;

2. apparatus of the present invention are simple in structure easy to operate with measuring method.

Description of drawings

Fig. 1 axial cone mirror surface-shaped detection device of the present invention is measured the schematic diagram of convex surface axial cone mirror

Fig. 2 is the index path that axial cone mirror surface-shaped detection device of the present invention is measured convex surface axial cone mirror

Fig. 3 is the schematic diagram that axial cone mirror surface-shaped detection device of the present invention is measured concave surface axial cone mirror

Fig. 4 is the index path that axial cone mirror surface-shaped detection device of the present invention is measured concave surface axial cone mirror

Embodiment

The invention will be further described below in conjunction with drawings and Examples, but should not limit protection scope of the present invention with this.

See also first Fig. 1 and Fig. 3, as seen from the figure, axial cone mirror surface-shaped detection device of the present invention, this device is comprised of phase-shifting interferometer 1, plane standard mirror 2, condenser lens 4 and plane mirror 5, its position relationship is: along on the described phase-shifting interferometer 1 outgoing beam working direction, be described plane standard mirror 2, condenser lens 4 and plane mirror 5 successively.The socket of axial cone mirror 3 to be measured is set between described plane standard mirror 2 and condenser lens 4.

Utilize described axial cone mirror surface-shaped measurement mechanism to carry out the measuring method of axial cone mirror surface-shaped, comprise the steps:

1. insert axial cone mirror 3 to be measured between the parallel beam direction plane standard mirror 2 of phase-shifting interferometer 1 output and condenser lens 4, the conical surface of described axial cone mirror 3 to be measured is towards the light direction of phase-shifting interferometer 1;

2. adjust light path: the light beam of described phase-shifting interferometer 1 outgoing forms parallel measuring beam through described plane standard mirror 2, and the light beam that returns through described plane standard mirror 2 forms reference beam; The parallel plane of adjusting described plane standard mirror 2 is vertical with described parallel beam; The plane of adjusting described axial cone mirror 3 to be measured is vertical with measuring beam, guarantees that simultaneously the axis of described axial cone mirror 3 overlaps with the axis of phase-shifting interferometer 1 outgoing beam; Adjust described condenser lens 4 vertical with measuring beam, guarantee that simultaneously the optical axis of described condenser lens 4 overlaps with the axis of phase-shifting interferometer 1 outgoing beam; The plane of adjusting described plane mirror 5 is vertical with optical axis;

3. described measuring beam sees through described axial cone mirror 3 to be measured and incides described condenser lens 4, through described condenser lens 4 light beam is converged on the described plane mirror 5, then return through described plane mirror 5, the reference beam that the measuring beam that this returns and plane standard mirror 2 return produces interferes;

4. the distance of adjusting between described condenser lens 4 and the axial cone mirror 3 to be measured obtains complete clearly interference fringe, utilizes described phase-shifting interferometer 1 to detect interference fringe, namely obtains the face shape information of described axial cone mirror 3 to be measured.

Embodiment 1-detects the face shape of convex surface axial cone mirror

Fig. 2 is the index path that axial cone mirror surface-shaped detection device of the present invention is measured convex surface axial cone mirror, and as seen from the figure, the axial cone mirror 3 to be measured of the embodiment of the invention 1 is convex surface axial cone mirror, and the step of measuring convex surface axial cone mirror surface-shaped is as follows:

1. insert axial cone mirror 3 to be measured between the parallel beam direction plane standard mirror 2 of phase-shifting interferometer 1 output and condenser lens 4, the conical surface of described axial cone mirror 3 to be measured is towards the light direction of phase-shifting interferometer 1;

2. adjust light path: the light beam of described phase-shifting interferometer 1 outgoing forms parallel measuring beam through described plane standard mirror 2, and the light beam that returns through described plane standard mirror 2 forms reference beam; The parallel plane of adjusting described plane standard mirror 2 is vertical with described parallel beam; The plane of adjusting described axial cone mirror 3 to be measured is vertical with measuring beam, guarantees that simultaneously described axial cone mirror 3 axis overlap with the axis of phase-shifting interferometer 1 outgoing beam; Adjust described condenser lens 4 vertical with measuring beam, guarantee that simultaneously the optical axis of described condenser lens 4 overlaps with the axis of phase-shifting interferometer 1 outgoing beam; The plane of adjusting described plane mirror 5 is vertical with optical axis;

3. the light beam of described phase-shifting interferometer 1 outgoing forms parallel measuring beam through described plane standard mirror 2, and the light beam that returns through described plane standard mirror 2 forms reference beam; Described measuring beam sees through described axial cone mirror 3 and incides described condenser lens 4, through described condenser lens 4 light beam is converged on the described plane mirror 5, then return through described plane mirror 5, the reference beam that the measuring beam that this returns and plane standard mirror 2 return produces interferes;

4. the distance of adjusting between described condenser lens 4 and the axial cone mirror 3 to be measured obtains complete clearly interference fringe, utilizes described phase-shifting interferometer 1 to detect interference fringe, thereby obtains the face shape information of described axial cone mirror 3.

The center thickness of described axial cone mirror 3 to be measured, edge thickness, refractive index and cone angle are respectively b, a, and n, θ, the refraction angle β of light beam behind axial cone mirror 3 to be measured is expressed as:

$\mathrm{\β}=\arcsin \left\{n\sin \right[\mathrm{\θ}-\arcsin \left(\frac{\sin \mathrm{\θ}}{n}\right)\left]\right\}---\left(1\right)$

Deviation light beam behind axial cone mirror 3 to be measured with respect to the difference in height Y that incident beam departs from is:

$Y=\frac{a+b}{2}\tan [\mathrm{\θ}-\arcsin \left(\frac{\sin \mathrm{\θ}}{n}\right)]---\left(2\right)$

Axial cone mirror 3 to be measured is expressed as to the distance P of described condenser lens 4 focus in object spaces:

$P=\frac{1}{2}(\mathrm{\Φ}-2Y)c\tan \mathrm{\β}---\left(3\right)$

Wherein, Φ is the clear aperture of axial cone mirror to be measured.

Thereby obtain described axial cone mirror 3 to be measured by following formula and should satisfy following relational expression to the distance L of described condenser lens 4:

L＝P+f (4)

Wherein, f is the object space focal length of described condenser lens 4.

So just, can utilize phase-shifting interferometer 1 to obtain interference fringe, thereby obtain the face shape information of axial cone mirror 3 to be measured.

Embodiment 2-measures convex surface axial cone mirror surface-shaped

Fig. 4 is the index path that axial cone mirror surface-shaped detection device of the present invention is measured concave surface axial cone mirror, and as seen from the figure, the axial cone mirror 3 to be measured of embodiment 2 is concave surface axial cone mirrors, and the step of measuring concave surface axial cone mirror surface-shaped is as follows:

1. insert successively plane standard mirror 2, concave surface axial cone mirror 3 to be measured, condenser lens 4 and plane mirror 5 in the parallel beam direction of phase-shifting interferometer 1 output, the conical surface of described axial cone mirror 3 to be measured is towards the light direction of phase-shifting interferometer 1;

2. adjust light path: the light beam of described phase-shifting interferometer 1 outgoing forms parallel measuring beam through described plane standard mirror 2, and the light beam that returns through described plane standard mirror 2 forms reference beam; The parallel plane of adjusting described plane standard mirror 2 is vertical with described parallel beam; The plane of adjusting described axial cone mirror 3 to be measured is vertical with measuring beam, guarantees that simultaneously described axial cone mirror 3 axis overlap with the axis of phase-shifting interferometer 1 outgoing beam; Adjust described condenser lens 4 vertical with measuring beam, guarantee that simultaneously the optical axis of described condenser lens 4 overlaps with the axis of phase-shifting interferometer 1 outgoing beam; The plane of adjusting described plane mirror 5 is vertical with optical axis;

3. the light beam of described phase-shifting interferometer 1 outgoing forms parallel measuring beam through described plane standard mirror 2, and the light beam that returns through described plane standard mirror 2 forms reference beam; Described measuring beam sees through described axial cone mirror 3 and incides described condenser lens 4, through described condenser lens 4 light beam is converged on the described plane mirror 5, then reflect back through described plane mirror 5, the reference beam that the measuring beam that this returns and plane standard mirror 2 return produces interferes;

4. the distance of adjusting between described condenser lens 4 and the axial cone mirror 3 to be measured obtains complete clearly interference fringe, utilizes described phase-shifting interferometer 1 to detect interference fringe, thereby obtains the face shape information of described axial cone mirror 3.

The center thickness of described axial cone mirror 3 to be measured, edge thickness, refractive index and cone angle are respectively b, a, and n, θ, the refraction angle β of light beam behind axial cone mirror 3 to be measured is expressed as:

$\mathrm{\β}=\arcsin \left\{n\sin \right[\mathrm{\θ}-\arcsin \left(\frac{\sin \mathrm{\θ}}{n}\right)\left]\right\}---\left(5\right)$

Deviation light beam behind axial cone mirror 3 to be measured with respect to the difference in height Y that incident beam departs from is:

$Y=\frac{a+\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA00002343859200011.png,HDA00002343859200012.png"\; state="\{\{state\}\}">b</figure-callout>}}{2}\tan [\mathrm{\&theta;}-\arcsin \left(\frac{\sin \mathrm{\&theta;}}{n}\right)]---\left(6\right)$

Axial cone mirror 3 to be measured is expressed as to the distance P of described condenser lens 4 focus in object spaces:

$P=\frac{1}{2}(\mathrm{\&Phi;}+2Y)c\tan \mathrm{\&beta;}---\left(7\right)$

Wherein, Φ is the clear aperture of axial cone mirror to be measured.

Thereby obtain described axial cone mirror 3 to be measured by following formula and should satisfy following relational expression to the distance L of described condenser lens 4:

L＝f-P (8)

Wherein, f is the object space focal length of described condenser lens (4).

So just, can utilize phase-shifting interferometer 1 to obtain interference fringe, namely obtain the face shape information of axial cone mirror 3 to be measured.

Experiment shows, the present invention has the advantages that apparatus structure is simple, measuring method is easy to operate.

Claims (3)

1. the measurement mechanism of an axial cone mirror surface-shaped, it is characterized in that this device is comprised of phase-shifting interferometer, plane standard mirror, condenser lens and plane mirror, its position relationship is: be described plane standard mirror, condenser lens and plane mirror successively along described phase-shifting interferometer outgoing beam working direction, the socket of axial cone mirror to be measured is set between described plane standard mirror and condenser lens.

2. utilize the measurement mechanism of axial cone mirror surface-shaped claimed in claim 1 to carry out the measuring method of axial cone mirror surface-shaped, it is characterized in that the method comprises the steps:

1. insert axial cone mirror to be measured at the plane standard mirror of the parallel beam direction of phase-shifting interferometer output and the socket of the axial cone mirror to be measured between the condenser lens, the conical surface of described axial cone mirror to be measured is towards the light direction of phase-shifting interferometer;

2. adjust light path: the parallel beam of described phase-shifting interferometer outgoing forms parallel measuring beam through described plane standard mirror, and the light beam that returns through described plane standard mirror forms reference beam; The parallel plane of adjusting described plane standard mirror is vertical with described parallel beam; The plane of adjusting described axial cone mirror to be measured is vertical with measuring beam, guarantees that simultaneously the axis of described axial cone mirror overlaps with the axis of phase-shifting interferometer outgoing beam; Adjust described condenser lens vertical with measuring beam, guarantee that simultaneously the optical axis of described condenser lens overlaps with the axis of phase-shifting interferometer outgoing beam; The plane of adjusting described plane mirror is vertical with optical axis;

3. described measuring beam sees through described axial cone mirror and incides described condenser lens, through described condenser lens light beam is converged on the described plane mirror, then return through described plane mirror reflection, the reference beam that the measuring beam that this returns and plane standard mirror return produces interferes;

4. the distance of adjusting between described condenser lens and the axial cone mirror to be measured obtains complete clearly interference fringe, utilizes described phase-shifting interferometer to detect interference fringe, namely obtains the face shape information of described axial cone mirror.

3. the measuring method of axial cone mirror surface-shaped according to claim 1 and 2 is characterized in that, described axial cone mirror to be measured is convex surface axial cone mirror or concave surface axial cone mirror.

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