CN102393565B - Reverse type inverse compensator - Google Patents

Abstract

The invention relates to a refraction and reflection type inverse compensator which is used for calibrating an aspheric surface zero detection compensator and comprises an interferometer, a lens, a negative lens and a reflecting spherical mirror, wherein the aspheric surface zero detection compensator to be calibrated is arranged between the interferometer and the lens; a negative lens is arranged between the reflective spherical mirror and the lens, the lens is used for correcting high-grade spherical aberration, and the negative lens is used for generating quantitative spherical aberration; after the light rays pass through the negative lens and the lens twice, the sum of the spherical aberration generated by the lens and the lens is equal to the theoretical spherical aberration of the aspheric surface zero detection compensator, and the signs are opposite; the single-wavelength divergent spherical wave emitted by the interferometer forms divergent spherical waves after passing through the aspheric surface zero detection compensator, the divergent spherical waves with spherical aberration sequentially pass through the lens and the negative lens to reach the reflective spherical mirror, the light beam passes through the negative lens and the lens for the second time after being reflected by the reflective spherical mirror and reaches the interferometer after passing through the aspheric surface zero detection compensator, and the system aberration of the aspheric surface zero detection compensator is detected through the interferometer.

Description

A kind of Reflecting type inverse compensator

Technical field

The present invention relates to for the Reflecting type inverse compensator of demarcating aspheric surface zero detection compensator, it is mainly used in the calibration that aspheric surface zero detects compensator.

Background technology

Aspheric surface occupies an important position in optics, and in most Large optical systems, its primary mirror is aspheric surface, particularly secondary aspherical.But up to the present, make aspheric surface more much more difficult than making sphere, wherein important reason is that aspheric detection is more much more difficult than sphere.

The present Main Means of the check of heavy caliber aspherical mirror is zero detection compensator, and wherein zero representative detection compensator is the Offner compensator.Because the method accuracy of detection is high, and the diameter of compensator is than little many of the diameter of tested aspheric mirror, therefore use more and more widely.The Offner compensator belongs to the normal aberration compensation, and this compensator is comprised of compensating glass and two positive lenss of field lens.Compensating glass almost all compensates the spherical aberration that aspheric surface produces, and field lens is imaged on compensating glass on aspheric surface.The light that light source sends arrives aspheric surface by compensating glass and field lens, and all light all incide on tested aspheric surface along normal.The essence of this penalty method is by compensator, plane or spherical wave are converted to aspherical wavefront and overlap with tested aspheric theoretical shape.By the wavefront of compensator outgoing, can be regarded as the test plate that is stacked on tested aspheric surface.In fact, the reference wavefront deviation that tested aspheric surface produces for compensator is amplified to twice and passes to the wavefront that is returned by compensator, and this and test plate method are just the same.Therefore, the Offner penalty method can be understood as by the little compensator of bore, produces huge bigbore contactless test plate, keeps simultaneously the principal advantages of test plate method.The characteristic of this technology is, near field lens aspheric surface vertex curvature center is projected in aspheric surface on compensating glass, can greatly reduce residual aberration like this, referring to " A Null Corrector for Paraboloidal Mirrors " Abe Offner.Applied Optics Vol.2 No.2.Yet this class zero detects compensator and has many-sided defective:

The first, Offner compensator visual field is very little, a few tenths of a mm of only having an appointment, and the light path coaxiality requires very high in actual heavy caliber aspherical mirror checkout procedure like this.Yet the check light path of large-scale aspheric surface primary mirror often reaches tens meters, and is even longer, satisfies coaxiality and requires to exist great difficulty.

The second, Offner compensator assembling difficult.For example, detect the Offner compensator of Φ 1800mm (F/1.5) parabola primary mirror, the space requirement of each minute surface 5 microns left and right, eccentric error is about 7 seconds.Such matching requirements have almost reached the engineering limit, and any point carelessness will cause serious systematic error.

The data of aperture aspherical primary mirror compensation tests directly instruct the processing of primary mirror, and its correctness has directly determined the processing result that primary mirror is final.Because the spherical aberration of the required compensation of compensator is directly proportional to the first power of primary mirror bore and the cube of relative aperture.Therefore, be a large spherical aberration system with regard to compensator self, particularly for the high steepness primary mirror of heavy caliber, all the more so.This has determined that also compensator is very sensitive to error, and small mistake and carelessness all will cause catastrophic consequence.The major accident that produces with regard to the problem that has occurred due to compensator in history.Therefore, how to realize the high precision calibration of compensator, improve the reliability of compensator, stop the appearance of similar accident, become one of top priority of aperture aspherical primary mirror processing.Existing compensation method is mainly to rely on the calculation holographic technology.Computed hologram (Computer-generated holograms, be called for short CGH) is to be proposed on the basis of Identification with Method of Optical Holography by American scientist A.J.Macgovern and J.C.Wyant in 1971.Its essence is the hologram that utilizes computing machine comprehensive, it does not need the physical presence of object, but after the mathematical description of object wave input computing machine, controls making apparatus and machine hologram.With CGH calibration compensation device, utilize exactly the reflection corrugated of the point diffraction wave surface simulation primary mirror of CGH, so just can closely, in small-bore situation, the aperture aspherical primary mirror of complete simulate ideal reflects the corrugated; Then utilize large scale integrated circuit equipment, produce the diffraction hologram sheet.But CGH manufacturing process has a lot of error sources, as site error of real estate shape, step etching depth and the groove of CGH etc., stated accuracy is made a big impact.Particularly the groove site error is larger to the point diffraction wave surface Accuracy of CGH, but can't determine accurately the site error of groove by directly measuring groove position and radius at present, and the hologram sheet precision of therefore making is uncertain.There is very large risk with its calibration compensation device.The different order of diffraction of hologram sheet time can cause adverse effect to detection equally, can form detecting disadvantageous extra interaction noise, and contrast is relatively poor.Along with the increase of aspheric surface primary mirror bore and the increase of relative aperture, aspheric aspherical degree increases sharply, and the reflection corrugated that hologram sheet will be simulated primary mirror needs the line thickness of etching very little, and existing equipment guarantees that enough etching precisions face significant challenge.Therefore, on the whole, at present there is very large technical risk in the demarcation means of aspheric surface compensator.

Summary of the invention

The present invention wants the technical solution problem to be: relatively existing aspheric surface compensator is demarcated the deficiencies such as means CGH precision is uncertain, poor contrast, making difficulty, but the purpose of this invention is to provide a kind ofly have that cost of manufacture is low, main error source accurate measurement, good contrast, processing are simple, be used for demarcating the Reflecting type inverse compensator that aspheric surface zero detects compensator.

For realizing described purpose, the technical solution that refraction-reflection type compensator technical solution problem provided by the invention adopts comprises: interferometer, lens, negative lens and reflecting spherical mirror, wherein: be provided with the aspheric surface zero of being demarcated and detect compensator between interferometer and lens; Be provided with negative lens between reflecting spherical mirror and lens, lens are used for proofreading and correct high-order spherical aberration, and negative lens is for generation of quantitative spherical aberration; Twice of light is by after negative lens and lens, the theoretical spherical aberration equal and opposite in direction opposite in sign of the spherical aberration sum that lens and lens produce and aspheric surface zero detection compensator; Single wavelength divergent spherical wave that interferometer sends, formed divergent spherical wave after detecting compensator through aspheric surface zero, should arrive reflecting spherical mirror with the divergent spherical wave of spherical aberration scioptics successively, negative lens, after light beam reflects through reflecting spherical mirror, for the second time by negative lens and lens, and arrive interferometer after detecting compensator by aspheric surface zero, by interferometer, the system aberration that aspheric surface zero detects compensator is detected.

Beneficial effect of the present invention: compared with prior art have the following advantages,

Reflecting type inverse compensator only comprises three optical elements, and wherein, negative lens has been born most amount of spherical aberration, and lens are mainly used to compensate the high-order spherical aberration that negative lens has not yet compensated, and the effect of reflecting spherical mirror is that light is returned along former road.Whole Reflecting type inverse compensator cost of manufacture is low, processes comparatively simple, conventional optics processing and just can realize required accuracy requirement.

But all precision measurements of the parameters such as the refractive index of each element, homogeneity, face shape error, thickness error, assembling interval error, eccentric error.Therefore, the reliability of this Reflecting type inverse compensator is greatly improved.

This Reflecting type inverse compensator is time interference problem at the same level invariably, and the contrast of its interference fringe can be similar to and reach 100%.

Description of drawings

Fig. 1 is Reflecting type inverse compensator of the present invention;

Fig. 2 is each symbol implication schematic diagram of the present invention.

Element explanation in figure:

1 is light source or interferometer;

2 is that aspheric surface zero detects compensator;

2a is the first lens (near the lens of interferometer) that aspheric surface zero detects compensator;

2b is second lens that aspheric surface zero detects compensator;

3 is lens;

3q is the lens first surface;

3h is second, lens;

4 is negative lens;

4q is the negative lens first surface;

4h is second of negative lens;

5 is reflecting spherical mirror;

Embodiment

Introduce in detail the present invention below in conjunction with the drawings and the specific embodiments.

As Fig. 1, Reflecting type inverse compensator of the present invention is shown, Reflecting type inverse compensator is used for that aspheric surface zero is detected compensator to be demarcated, and Reflecting type inverse compensator of the present invention comprises interferometer 1, lens 3, negative lens 4 and reflecting spherical mirror 5.Wherein, be provided with the aspheric surface zero of being demarcated between interferometer 1 and lens 3 and detect compensator 2; Be provided with negative lens 4 between reflecting spherical mirror 5 and lens 3, lens 3 are used for proofreading and correct high-order spherical aberration, and negative lens 4 is for generation of quantitative spherical aberration; After light passed through negative lens 4 and lens 3 twice, the spherical aberration sum that lens 4 and lens 3 produce and aspheric surface zero detected the theoretical spherical aberration equal and opposite in direction opposite in sign of compensator 2; Single wavelength divergent spherical wave that interferometer 1 sends, formed divergent spherical wave after detecting compensator 2 through aspheric surface zero, should arrive reflecting spherical mirrors 5 with the divergent spherical wave of spherical aberration scioptics 3 successively, negative lens 4, after light beam reflects through reflecting spherical mirror 5, for the second time by negative lens 4 and lens 3, and detecting the rear arrival interferometer 1 of compensator 2 by aspheric surface zero, the system aberration that detects compensator 2 by 1 pair of aspheric surface of interferometer zero detects.

The coefficient of spherical aberration S of described lens 3 ₂Satisfy:

${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=\frac{I_1{L}_1\sin U_1(\sin I_1-\sin I_1^{\&prime;})(\sin I_1^{\&prime;}-\sin U_1)}{\cos \frac{1}{2}(I_1-U_1)\cos \frac{1}{2}(I_1^{\&prime;}+U_1)\cos \frac{1}{2}(I_1+I_1^{\&prime;})}$

$+\frac{n_a{I}_2{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2\sin U_2(\sin I_2-\sin I_2^{\&prime;})(\sin I_2^{\&prime;}-\sin U_2)}{\cos \frac{1}{2}(I_2-U_2)\cos \frac{1}{2}(I_2^{\&prime;}+U_2)\cos \frac{1}{2}(I_2+I_2^{\&prime;})}$

$=-S_0/2-{\mathrm{<figure-callout\; id="3"\; label="S"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_3$

S in formula ₀Detect the coefficient of spherical aberration of compensator 2 for aspheric surface zero; S ₃Be the coefficient of spherical aberration of negative lens 4, I ₁, I ' ₁, U ₁, L ₁, be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of the first surface 3q of lens 3;

N in formula _aRefractive index for lens 3; I ₂, I ' ₂, U ₂, L ₂Be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of second 3h of lens (3);

$I_1=\arcsin \left(\frac{L_1-r_1}{r_1}\sin \left(U_1\right)\right),$

$I_1^{\&prime;}=\arcsin \left(\frac{1}{n_a}\sin I_1\right),$

U ₂＝U ₁+I ₁-I′ ₁，

${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2=r_1+r_1\frac{\sin I_1^{\&prime;}}{\sin U_1^{\&prime;}}-d_1,$

$I_2=\arcsin \left(\frac{L_2-r_2}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}\sin \left(U_2\right)\right),$

I′ ₂＝arcsin(n _a×sin(I ₂))；

In formula: r ₁Radius for lens 3 first surface 3q; U′ ₁Be the picture side aperture angle of light for lens 3 first surface 3q; d ₁Thickness for lens 3; r ₂Radius for 3 second 3h of lens.

The negative lens 4 of described Reflecting type inverse compensator is characterized in that: its coefficient of spherical aberration S ₃Satisfy:

${\mathrm{<figure-callout\; id="3"\; label="S"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_3=\frac{I_3{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_3\sin U_3(\sin I_3-\sin I_3^{\&prime;})(\sin I_3^{\&prime;}-\sin U_3)}{\cos \frac{1}{2}(I_3-U_3)\cos \frac{1}{2}(I_3^{\&prime;}+U_3)\cos \frac{1}{2}(I_3+I_3^{\&prime;})}$

$+\frac{n_b{I}_4{L}_4\sin U_4(\sin I_4-\sin I_4^{\&prime;})(\sin I_4^{\&prime;}-\sin U_4)}{\cos \frac{1}{2}(I_4-U_4)\cos \frac{1}{2}(I_4^{\&prime;}+U_4)\cos \frac{1}{2}(I_4+I_4^{\&prime;})}$

$\&ap;-S_0/2$

S in formula ₀Detect the coefficient of spherical aberration of compensator 2 for aspheric surface zero; n _bRefractive index for negative lens 4; I ₃, I ₃', U ₃, L ₃Be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of negative lens 4 first surface 4q.

I in formula ₄, I ₄', U ₄, L ₄Be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of 4 second 4h of negative lens;

${\mathrm{<figure-callout\; id="3"\; label="I"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">I</figure-callout>}}_3=\arcsin \left(\frac{L_3-r_3}{{\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">r</figure-callout>}}_3}\sin \left(U_3\right)\right),$

I′ ₃＝arcsin(sin(I ₃)/n _b)，

U ₄＝U ₃+I ₃-I′ ₃；

$L_4={\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">r</figure-callout>}}_3+{\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">r</figure-callout>}}_3\frac{\sin {\mathrm{<figure-callout\; id="3"\; label="I"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">I</figure-callout>}}_3^{\&prime;}}{\sin {\mathrm{<figure-callout\; id="3"\; label="U"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">U</figure-callout>}}_3^{\&prime;}}-{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA0000101078540000011.png"\; state="\{\{state\}\}">d</figure-callout>}}_2,$

$I_4=\arcsin \left(\frac{L_4-r_4}{r_4}\sin \left(U_4\right)\right),$

I′ ₄＝arcsin(n _b×sin(I ₄))；

R in formula ₃Radius for negative lens 4 first surface 4q; U ₃' be that light is for picture side's aperture angle, the d of negative lens 4 first surface 4q ₂Thickness for negative lens 4; r ₄Radius for 4 second 4h of negative lens.

Described rays pass through lens 3, the rear formation divergent spherical wave of negative lens 4.

The centre of sphere of described reflecting spherical mirror 5 overlaps with the centre of sphere of the divergent spherical wave of rays pass through lens 3, negative lens 4 rear formation.Therefore light is after catoptron 5 reflections, and former road is returned, and again by negative lens 4, lens 3, then arrives interferometer by compensator and completes detection.

Utilize Reflecting type inverse compensator to detect compensator 2 (aspheric surface as shown in fig. 1 zero detects compensator 2, is comprised of first lens 2a, second lens 2b) to aspheric surface zero and demarcate, concrete optical parametric is as shown in table 1:

Table 1

Optical parametric and performance index:

Numerical aperture NA=0.13,

Operation wavelength λ=0.6328 μ m,

Aspheric surface zero detects compensator coefficient of spherical aberration S ₀=2.735

The coefficient of spherical aberration S of lens (3) ₂=0.00079

The coefficient of spherical aberration S of negative lens (4) ₃=-1.367

The corrugated aberration: PV=0.025 λ, RMS=0.005 λ,

Greatest optical element bore:

Fig. 2 is each symbol implication schematic diagram of the present invention, and wherein, ∑ is a workplace of a certain element, I _iBe incident angle, I _i' be the refraction angle, U _iBe object space aperture angle, U _i' be picture side's aperture angle, r _iBe the radius of workplace ∑, O _iBe the summit of workplace ∑, L _iBe object space intercept, L _i' being picture side's intercept, A is object point, A ' is picture point.

The non-elaborated part of the present invention belongs to techniques well known.

The above; only be the embodiment in the present invention, but protection scope of the present invention is not limited to this, anyly is familiar with the people of this technology in the disclosed technical scope of the present invention; can understand conversion or the replacement expected, within all should being encompassed in the scope that claim of the present invention comprises.

Claims (5)

1. Reflecting type inverse compensator is characterized in that comprising: interferometer, first lens, the first negative lens and reflecting spherical mirror, wherein:

Be provided with the aspheric surface zero of being demarcated and detect compensator between interferometer and first lens;

Be provided with the first negative lens between reflecting spherical mirror and first lens, first lens is used for proofreading and correct high-order spherical aberration, and the first negative lens is for generation of quantitative spherical aberration;

After light passed through the first negative lens and first lens twice, the spherical aberration sum that the first negative lens and first lens produce and aspheric surface zero detected the theoretical spherical aberration equal and opposite in direction opposite in sign of compensator; Single wavelength divergent spherical wave that interferometer sends, formed divergent spherical wave after detecting compensator through aspheric surface zero, should arrive reflecting spherical mirror by first lens, the first negative lens successively with the divergent spherical wave of spherical aberration, after light beam reflects through reflecting spherical mirror, for the second time by the first negative lens and first lens, and arrive interferometer after detecting compensator by aspheric surface zero, by interferometer, the system aberration that aspheric surface zero detects compensator is detected.

2. Reflecting type inverse compensator according to claim 1 is characterized in that: the coefficient of spherical aberration S2 of first lens satisfies:

$S_2=\frac{I_1{L}_1\sin U_1(\sin I_1-\sin I_1^{\&prime;})(\sin I_1^{\&prime;}-\sin U_1)}{\cos \frac{1}{2}(I_1-U_1)\cos \frac{1}{2}(I_1^{\&prime;}+U_1)\cos \frac{1}{2}(I_1+I_1^{\&prime;})}$

$+\frac{n_a{I}_2{L}_2\sin U_2(\sin I_2-\sin I_2^{\&prime;})(\sin I_2^{\&prime;}-\sin U_2)}{\cos \frac{1}{2}(I_2-U_2)\cos \frac{1}{2}(I_2^{\&prime;}+U_2)\cos \frac{1}{2}(I_2+I_2^{\&prime;})}$

$=-S_0/2-S_3$

S in formula ₀Detect the coefficient of spherical aberration of compensator for aspheric surface zero; S ₃Be the coefficient of spherical aberration of the first negative lens, I ₁, I _'1, U ₁, L ₁Be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of the first surface of first lens;

N in formula _aRefractive index for first lens; I ₂, I ' ₂, U ₂, L ₂Be respectively light for the incident angle of second, refraction angle, object space aperture angle, the object space intercept of first lens;

$I_1=\arcsin \left(\frac{L_1-r_1}{r_1}\sin \left(U_1\right)\right),$

$I_1^{\&prime;}=\arcsin \left(\frac{1}{n_a}{\sin I}_1\right)$

U ₂＝U ₁+I ₁-I′ ₁，

$L_2=r_1+r_1\frac{{\sin I}_1^{\&prime;}}{{\sin U}_1^{\&prime;}}-d_1$

$I_2=\arcsin \left(\frac{L_2-r_2}{r_2}\sin \left(U_2\right)\right),$

I′ ₂＝arcsin(n _a×sin(I ₂))；

In formula: r ₁Radius for the first surface of first lens; U ₁' be that light is for picture side's aperture angle of the first surface of first lens; d ₁Thickness for first lens; r ₂The radius of second for first lens; The first surface of described first lens is to detect the one side of compensator near aspheric surface zero, and the second face of described first lens is to detect the one side of compensator away from aspheric surface zero.

3. Reflecting type inverse compensator according to claim 1, is characterized in that: the coefficient of spherical aberration S of described the first negative lens ₃Satisfy:

$S_3=\frac{I_3{L}_3\sin U_3(\sin I_3-\sin I_3^{\&prime;})(\sin I_3^{\&prime;}-\sin U_3)}{\cos \frac{1}{2}(I_3-U_3)\cos \frac{1}{2}(I_3^{\&prime;}+U_3)\cos \frac{1}{2}(I_3+I_3^{\&prime;})}$

$+\frac{n_b{I}_4{L}_4\sin U_4(\sin I_4-\sin I_4^{\&prime;})(\sin I_4^{\&prime;}-\sin U_4)}{\cos \frac{1}{2}(I_4-U_4)\cos \frac{1}{2}(I_4^{\&prime;}+U_4)\cos \frac{1}{2}(I_4+I_4^{\&prime;})}$

$\&ap;-S_0/2$

S in formula ₀Detect the coefficient of spherical aberration of compensator for aspheric surface zero; n _bIt is the refractive index of the first negative lens; I ₃, I ₃', U ₃, L ₃Be respectively light for incident angle, refraction angle, object space aperture angle, the object space intercept of the first surface of the first negative lens;

I in formula ₄, I ₄', U ₄, L ₄Be respectively light for the incident angle of second, refraction angle, object space aperture angle, the object space intercept of the first negative lens;

$I_3=\arcsin \left(\frac{L_3-r_3}{r_3}\sin \left(U_3\right)\right),$

I′ ₃＝arcsin(sin(I ₃)/n _b)，

U ₄＝U ₃+I ₃-I′ ₃；

$L_4=r_3+r_3\frac{{\sin I}_3^{\&prime;}}{{\sin U}_3^{\&prime;}}-d_2,$

$I_4=\arcsin \left(\frac{L_4-r_4}{r_4}\sin \left(U_4\right)\right),$

I′ ₄＝arcsin(n _b×sin(I ₄))；

R in formula ₃It is the radius of the first surface of the first negative lens; U ₃' be that light is for picture side's aperture angle, the d of the first surface of the first negative lens ₂Be the thickness of the first negative lens; r ₄It is the radius of second of the first negative lens; The first surface of described the first negative lens is the one side away from reflecting spherical mirror, and the second face of described the first negative lens is the one side near reflecting spherical mirror.

4. Reflecting type inverse compensator according to claim 1 is characterized in that: light forms divergent spherical wave after by first lens, the first negative lens.

5. Reflecting type inverse compensator according to claim 1 is characterized in that: the centre of sphere of the divergent spherical wave that the centre of sphere of described reflecting spherical mirror and light form after by first lens, the first negative lens overlaps.

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