CN116105594A - Fizeau interferometer for realizing high interference contrast by adapting to reflectivity of detection surface - Google Patents

Fizeau interferometer for realizing high interference contrast by adapting to reflectivity of detection surface Download PDF

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Publication number
CN116105594A
CN116105594A CN202211639208.9A CN202211639208A CN116105594A CN 116105594 A CN116105594 A CN 116105594A CN 202211639208 A CN202211639208 A CN 202211639208A CN 116105594 A CN116105594 A CN 116105594A
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light
polarization
lens group
reflectivity
medium
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钱俊
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SHANGHAI MODERN ADVANCED ULTRA PRECISION MANUFACTURING CENTER CO LTD
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SHANGHAI MODERN ADVANCED ULTRA PRECISION MANUFACTURING CENTER CO LTD
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The invention relates to the technical field of optics. A Fizeau interferometer for realizing high interference contrast by adapting to the reflectivity of a detection surface comprises a laser light source, a 1/2 wave plate, a converging lens group, an illumination diaphragm, a polarization beam splitter, a collimating lens group, a Faraday rotator and a polarization reference lens group which are sequentially arranged along a first light path direction; the imaging diaphragm, the imaging lens group and the ccd camera are sequentially arranged along the second light path direction; the 1/2 wave plate is arranged on a rotating mechanism for adjusting the angle of the fast axis; the first light path direction is the same as the transmission optical axis direction of the polarization beam splitter, and the second light path direction is the same as the reflection optical axis direction of the polarization beam splitter. The maximum light intensity of the interference signal is regulated by the output power of the laser light source and the 1/2 wave plate; the contrast of the interference signal is adjusted by a faraday rotator.

Description

Fizeau interferometer for realizing high interference contrast by adapting to reflectivity of detection surface
Technical Field
The invention relates to the technical field of optics, in particular to a Fizeau interferometer.
Background
Interferometer measurements are very widely used as high precision devices for modern optical detection.
The Fizeau interferometer has the characteristic of common optical path of reference light and measuring light which interfere in detection through a unique optical path structure, so that most of system detection errors caused by optical component processing and instrument adjustment are counteracted, and the detection precision is improved. However, according to the interference principle, the interference contrast of two beams of light is the ratio of the difference between the maximum value and the minimum value of the intensity of interference fringes to the sum of the maximum value and the minimum value. For the Fizeau interferometer, due to the common light path characteristic, the light intensity of the reference light and the measuring light is difficult to match, and when the reflectivity of the detection surface is too high or too low (such as after the detection surface is coated), the interference contrast is often low. Although the influence of low interference contrast on the interferometry accuracy can be reduced to a certain extent with the expansion of the dynamic range of the ccd camera and the development of the modern phase analysis technology, the problem of interference contrast is always an important factor affecting the detection measurement accuracy of the Fizeau interferometer in principle, and the measurement accuracy of the Fizeau interferometer on the detection surface with high and low reflectivity is often limited. Still according to the interference principle, when the reference light and the measuring light are linearly polarized light with the same polarization direction and the polarization amplitude (light intensity) is also the same, the two light beams can form complete coherence, the interference contrast is highest, and the accuracy of interference phase information analyzed in principle is highest (no measurement and analysis errors in principle).
In order to solve the problem of interference contrast, the conventional manner of the Fizeau interferometer is to additionally introduce an energy attenuation device in an external detection light path or to plate a reflection enhancing film on a reference surface of a reference mirror, which has the defects that an additional system detection error is introduced, the energy ratio of the reference light to the measurement light cannot be continuously adjusted, the energy of the reference light and the measurement light can only be close within a certain range, the highest interference contrast cannot be realized in principle, and the optimal interference detection precision cannot be realized.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a Fizeau interferometer which adapts to the reflectivity of a detection surface to realize high interference contrast, and at least one technical problem is solved.
The technical scheme of the invention is as follows: the Fizeau interferometer is characterized by comprising a laser light source, a 1/2 wave plate, a converging lens group, an illumination diaphragm, a polarization beam splitter, a collimating lens group, a Faraday rotator and a polarization reference lens group which are sequentially arranged along a first light path direction, wherein the Fizeau interferometer is adaptive to the reflectivity of a detection surface to realize high interference contrast;
the imaging diaphragm, the imaging lens group and the ccd camera are sequentially arranged along the second light path direction;
the first light path direction is the same as the transmission optical axis direction of the polarization beam splitter, and the second light path direction is the same as the reflection optical axis direction of the polarization beam splitter;
the 1/2 wave plate is arranged on a rotating mechanism for adjusting the angle of the fast axis; the polarization direction of the transmitted light beam is changed by rotating the 1/2 wave plate, and finally the energy attenuation of the transmitted light beam is realized by matching with the polarization beam splitter, and the attenuation proportion is continuously adjustable;
the incident light of the polarization reference lens group is linearly polarized light, the returned reference light is linearly polarized light, the polarization direction of the returned reference light is the same as that of the incident light, and the returned measurement light is linearly polarized light, and the polarization direction of the returned reference light is perpendicular to that of the incident light;
the returned reference light and the measuring light enter the Faraday rotator again and then synchronously rotate in the polarization direction, and then pass through the polarization beam splitter again; the reference light and the measuring light entering the polarization beam splitter have different polarization directions;
the imaging lens group images the reference light and the measuring light to the focal plane of the ccd camera and forms interference signals; the reference light and the measuring light at the focal plane of the ccd camera are linearly polarized light with the same polarization direction, and at this time, the contrast ratio of the interference signal is determined by the ratio of the reference light intensity to the measuring light intensity.
The maximum light intensity of the interference signal of the interferometer is commonly regulated by the output power of the laser light source and the 1/2 wave plate, and can be continuously regulated in any range, so that the intensity of the interference signal is ensured to be in the dynamic range of the ccd camera;
the contrast of the interferometer interference signal is adjusted by the Faraday rotator. And the contrast ratio can be arbitrarily adjusted from 0 to 1, and especially the theoretical maximum contrast ratio of 1 can be realized.
Further preferably, the rotation mechanism is an electric rotation mechanism.
And electric control is convenient.
Further preferably, the illumination diaphragm is located at the focal position of the converging lens group, the aperture of the illumination diaphragm is smaller than the theoretical Airy spot diameter of the converging lens group, and the illumination diaphragm and the converging lens group cooperate to generate an approximately ideal aberration-free point as a light source of a subsequent light path.
Further preferably, the polarization reference lens group comprises a first medium, a reference surface, a second medium and an antireflection film which are sequentially arranged along the first light path direction;
the first medium is an amorphous optical medium;
the second medium is a birefringent crystalline optical medium.
The antireflection film eliminates the reflected stray light generated by the second medium. The reference light reflectivity at the reference plane is determined by the refractive index difference of the first medium and the second medium.
Further preferably, the second medium is a 1/4 wave plate.
Further preferably, the first medium is fused silica optical glass.
Further preferably, the second medium is magnesium fluoride birefringent crystal.
Further preferably, the antireflection film is a multilayer antireflection film. Preferably four antireflective films.
Further preferably, the first medium and the second medium are connected through optical cement.
Further preferably, the polarizing beam splitter transmits P polarized light and reflects S polarized light.
Further preferably, the polarizing beam splitter includes any one of a PBS optical film, a polarizing diffraction device, and a micro polarizing element array.
The method has the advantages that the method can perfectly solve the problem of energy matching of the common-path reference light and the measurement light of the Fizeau interferometer, can realize random adjustment of the ratio of the reference light to the measurement light intensity under the reflectivity of any detection surface without an external device or replacement of interferometer components, and can realize the highest interference contrast of theory, thereby improving the measurement range and the measurement precision of the Fizeau interferometer in principle.
Drawings
FIG. 1 is a schematic illustration of the present invention;
FIG. 2 is a schematic diagram of a polarization reference lens group according to the present invention;
FIG. 3 is a schematic diagram showing the adjustment of the ratio of the reference light to the measured light intensity when the reflectivity of the detection surface is high;
FIG. 4 is a schematic diagram showing the adjustment of the ratio of the reference light to the measured light intensity when the reflectivity of the detection surface is low.
In the figure: 1-1 is a laser light source; 1-2 is a 1/2 wave plate; 1-3 are converging lens groups; 1-4 are illumination diaphragms; 1-5 are polarizing beam splitters; 1-6 are collimating lens groups; 1-7 are Faraday rotators; 1-8 are polarization reference lens groups; 1-9 are imaging diaphragms; 1-10 is imaging lens group; 1-11 are ccd cameras; 1-12 are detection surfaces; 2-1 is a first medium; 2-2 is a second medium; 2-3 are reference surfaces and 2-4 are antireflection films.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1 to 4, embodiment 1 is a fizeau interferometer adapted to the reflectivity of the detection surface to achieve high interference contrast, and includes a laser light source 1-1, a 1/2 wave plate 1-2, a converging lens group 1-3, an illumination diaphragm 1-4, a polarizing beam splitter 1-5, a collimating lens group, a faraday rotator 1-8, and a polarizing reference lens group sequentially arranged along the first optical path direction. The polarization reference lens group is located between the Faraday rotator 1-8 and the detection surface 1-12.
The camera also comprises an imaging diaphragm 1-9, an imaging lens group 1-10 and a ccd camera 1-11 which are sequentially arranged along the second light path direction; the 1/2 wave plate 1-2 is arranged on a rotating mechanism for adjusting the angle of the fast axis; the incident light of the polarization reference lens group is linearly polarized light, the returned reference light is linearly polarized light and has the same polarization direction as that of the incident light, and the returned measurement light is linearly polarized light and has the polarization direction perpendicular to that of the incident light; the first optical path direction is the same as the transmission optical axis direction of the polarizing beam splitter 1-5, and the second optical path direction is the same as the reflection optical axis direction of the polarizing beam splitter 1-5.
The laser light source 1-1 outputs a polarized light laser as a light source of an optical path described later. The laser light source 1-1 here includes a laser that directly outputs a polarized light beam, and also includes a laser that outputs a polarized light beam through an external polarizing device.
The 1/2 wave plate 1-2 rotates the wave plate along the optical axis by means of an electric drive. The 1/2 wave plate 1-2 rotates by electric driving, adjusts the deflection direction of the fast axis and is used for adjusting the polarization direction of the passing light beam. The rotation 1/2 wave plate 1-2 of the polarization beam splitter 1-5 described later is matched to realize the variable energy attenuation function.
The converging lens group and the illumination diaphragms 1-4 are used for converging parallel light beams and forming an ideal point light source without aberration as an interference light source. The illumination diaphragms 1-4 are positioned at the focal positions of the converging lens groups, and the aperture of each illumination diaphragm is smaller than or equal to the theoretical Airy spot diameter of the converging lens groups. The illumination diaphragm and the converging lens group are matched to generate an approximately ideal aberration-free point which is used as a light source of a subsequent light path.
The polarizing beam splitters 1-5 are PBS optical film beam splitters. The polarizing beam splitters 1 to 5 realize functions through the PBS optical film, transmit polarized light with the polarization direction parallel to the PBS film surface, and reflect polarized light with the polarization direction not parallel to the PBS film surface. Alternatively, the polarizing beam splitter 1-5 implementations herein include polarizing diffraction devices, micro-polarizer arrays, and the like.
The position of the focus transmitted by the collimating lens group through the polarizing beam splitter 1-5 coincides with the position of the illumination diaphragm 1-4, and the position of the focus reflected by the polarizing beam splitter 1-5 coincides with the position of the imaging diaphragm 1-9. The collimator lens group collimates the light beam transmitted along the first light path direction into parallel light beams, and converges the light beam transmitted against the first light path direction. The collimating lens group and the converging lens group 1-3 have different focal lengths, and the beam expanding function is realized by matching. The collimating lens group coincides with the focal points of the imaging lens groups 1-10, so that interference imaging is realized.
The Faraday rotator 1-8 is an adjustable electromagnetic rotator 1-8, and can realize continuous adjustment of rotation of polarization angles. The faraday rotator 1-8 realizes rotation of the polarization direction of the light beam by an electromagnetic mode, and realizes rotation angle adjustment by adjusting current intensity. Alternatively, faraday rotators 1-8 achieve rotation angle adjustment by a variable Verdet constant or variable magnetic field optical path length. The adjustment of the rotation angle of the Faraday rotator 1-8 controls the polarization direction of the light beam entering the reference mirror group.
The polarization reference lens group is characterized in that incident light is linearly polarized light, return reference light is linearly polarized light, the polarization direction of the return reference light is identical to that of the incident light, and return measurement light is linearly polarized light, and the polarization direction of the return reference light is perpendicular to that of the incident light. The returned reference light and the measuring light enter the Faraday rotator 1-8 again, then the polarization directions are synchronously rotated, and the reference light and the measuring light pass through the polarization beam splitter 1-5 again. The polarization beam splitter 1-5 transmits the beam component with the polarization direction parallel to the PBS film surface, and only reflects the beam component with the polarization direction not parallel to the PBS film surface to enter the subsequent imaging lens group 1-10, so that the energy attenuation of the interference beam is realized. Whereas the reference light and the measuring light entering the polarizing beam splitters 1-5 have different (mutually orthogonal) polarization directions, the reference light and the measuring light reaching the interference focal plane have different energy attenuation ratios. By adjusting the optical rotation angle of the Faraday rotators 1-8, an arbitrary ratio of reference light and measured light intensity can be realized.
The imaging lens group 1-10 images the reference light and the measurement light to the focal plane of the ccd camera 1-11 and forms an interference signal.
The novel Fizeau interferometer adopts a wavelength phase shifting mode to carry out interferometry, alternatively, the novel Fizeau interferometer adopts a mechanical phase shifting direction to carry out interferometry.
The main functions realized are described as follows: 1) The maximum light intensity of the interferometer interference signal is regulated by the output power of the laser light source 1-1 and the 1/2 wave plate 1-2, and can be regulated in any range continuously, so that the intensity of the interference signal is ensured to be in the dynamic range of the ccd camera 1-11; 2) The contrast of the interferometer interference signal is adjusted by Faraday rotators 1-8, and the contrast can be arbitrarily adjusted from 0-1, and especially a theoretical maximum contrast of 1 can be achieved.
As shown in FIG. 2, the polarization reference lens group comprises a first medium 2-1, a reference surface 2-3, a second medium 2-2 and an antireflection film 2-4 which are sequentially arranged along the light path direction. The first medium 2-1 is an amorphous optical medium material having a refractive index N. The second medium 2-2 is a birefringent crystal optical medium having an o-ray refractive index No and an e-ray refractive index Ne. Wherein, no may be equal to N or may be unequal to N; ne may be equal to N or unequal to N; no and Ne must not be equal. And the second medium 2-2 has a specific thickness characteristic, so that the polarized light passing through the second medium 2-2 generates 45-degree phase retardation, i.e. has the characteristic of a 1/4 wave plate. When the light beam is transmitted back and forth through the second medium 2-2 twice, the polarized light causes a phase delay of 90 °, i.e. the polarization direction of the linearly polarized light is rotated by 90 °. The reference surface 2-3 is located at the interface of the first medium 2-1 and the second medium 2-2. The reflectivity of the reference surface 2-3 is determined by the refractive index difference between the first medium 2-1 and the second medium 2-2 according to the fresnel reflectivity formula. When the polarization direction of the incident light beam changes, the reflectance of the reference surface 2-3 varies in a range.
The main functions implemented by the polarization reference lens group are described as follows: 1) When the incident light beam is linearly polarized light, the reference light returned by the polarized reference lens group is linearly polarized light, and the polarization direction of the reference light is consistent with that of the incident light; 2) When the incident light beam is linearly polarized light, the polarized reference lens group returns the detection light to be linearly polarized light, and the polarization direction of the detection light is vertical to the incident light; 3) When the polarization direction of the incident polarized light beam changes, the polarization directions of the returned reference light and the measuring light synchronously change in a rotating way, and the returned reference light and the measuring light are kept orthogonal to each other.
In the present embodiment
The first medium 2-1 is fused silica optical glass.
The second medium 2-2 is magnesium fluoride birefringent crystal, and the fast axis direction of the magnesium fluoride crystal is parallel to the reference plane and perpendicular to the optical axis direction of the reference mirror. The magnesium fluoride birefringent crystal has a specific thickness, and the light beam passing through the magnesium fluoride crystal is delayed in phase by 45 degrees, namely, the magnesium fluoride birefringent crystal has the characteristic of a 1/4 wave plate.
The reference surface 2-3 is positioned at the interface of the fused silica optical glass and the magnesium fluoride birefringent crystal, and the reflectivity and the transmissivity of the interface are determined by a Fresnel refractive index formula. In this example, the reference plane is a plane.
The anti-reflection film 2-4 is positioned on the rear surface of the magnesium fluoride birefringent crystal and is a common 4-layer film stack AR film for reducing stray light.
The structure of the preferred embodiment of the present invention is described as follows:
the laser light source 1-1 outputs a polarized light beam with the polarization direction being horizontal, the cross-section diameter of the light beam being 5mm, and the coherence length being >100m.
The 1/2 wave plate 1-2 is a 0-stage 1/2 wave plate 1-2 with the phase delay deviation smaller than 1 DEG, and the initial optical axis position of the wave plate is horizontal. The focal length of the converging lens group 1-3 is 23mm, and the entrance pupil diameter is 6mm.
The illumination diaphragm 1-4 is a metal aperture with a diameter of 8um.
The polarizing beam splitters 1-5 transmit polarized light beams with polarization directions in the horizontal direction, the transmittance Tp of the polarized light beams is more than 99.9%, and reflect polarized light beams with polarization directions in the vertical direction, and the reflectivity Rs of the polarized light beams is more than 99.9%.
The focal length of the collimating lens group is 600mm, and the exit pupil diameter is 105mm.
The aperture of Faraday rotator 1-8 is 105mm, and the rotation angle is 0+ -45 deg.
The polarization reference lens group is a plane reference lens, the surface shape error precision PV of the reference surface 2-3 is less than 60nm (including curvature error), the polarization degree of returned reference light is more than 95%, the polarization degree of measured light is more than 95%, and the included angle between the reference light and the polarization direction of the measured light is 90 degrees+/-1 degrees.
The reflectivity=0.5% of the reference light directly returned by the polarization reference lens group, and the transmittance of the measuring light directly emitted by the polarization reference lens group is more than 99%.
The imaging diaphragm 1-9 is an stray light eliminating aperture diaphragm, and the light passing diameter is 9.5mm.
The focal length of the imaging lens groups 1-10 is 43mm.
The detection surface size of the ccd cameras 1 to 11 is 3.584mm× 3.584mm.
When the novel Fizeau interferometer of the best embodiment is used for measuring the detection surface with the reflectivity of >90%, the ratio of the reference light and the measured light intensity realized by the 1/2 wave plate 1-2 and the Faraday rotator 1-8 is adjusted to be shown in figure 3.
In the left region of fig. 3, a is a faraday rotator back reference light polarization schematic; the position b is a Faraday rotator post-measurement light polarization indication; c is reference light polarization indication after the polarization beam splitter; and d is the polarization indication of the measured light after the polarization beam splitter. In the right region in fig. 3, a reference light polarization indication after the faraday rotator (after adjustment of the angle of rotation of the faraday rotator) is shown at a 1; b1 is the polarization indication of the measured light after Faraday rotator (after Faraday rotator rotation angle adjustment); c1 is reference light polarization indication after the polarization beam splitter (after the adjustment of the optical rotation angle of the Faraday rotator); and d1 is the polarization indication of the measured light after the polarization beam splitter (after the adjustment of the rotation angle of the Faraday rotator).
When the novel Fizeau interferometer of the best embodiment is used for measuring the detection surface with the reflectivity less than 0.1%, the ratio of the reference light and the measured light intensity realized by the 1/2 wave plate 1-2 and the Faraday rotator 1-8 is adjusted to be schematic, as shown in figure 4.
In the left region of fig. 4, the reference light polarization schematic behind the faraday rotator is shown at e; f is the polarization indication of the measured light after Faraday rotator; g is the reference light polarization indication after the polarization beam splitter; and h is the polarization indication of the measured light after the polarization beam splitter.
In the right region in fig. 4, reference light polarization indication after faraday rotator (after faraday rotator rotation angle adjustment) is shown at e 1; the f1 is the polarization indication of the measured light after the Faraday rotator (after the adjustment of the rotation angle of the Faraday rotator); g1 is reference light polarization indication (after Faraday rotator rotation angle adjustment) after the polarization beam splitter; and h1 is the polarization indication of the measured light after the polarization beam splitter (after the adjustment of the rotation angle of the Faraday rotator).
According to the experimental result of the optimal embodiment, the invention can adapt to extremely high or extremely low reflectivity of the reflecting surface, regulate the reference light and the measuring light in any proportion, realize the highest interference contrast of theory, and have no extra error introduced in principle, thereby being convenient to operate.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The Fizeau interferometer is characterized by comprising a laser light source, a 1/2 wave plate, a converging lens group, an illumination diaphragm, a polarization beam splitter, a collimating lens group, a Faraday rotator and a polarization reference lens group which are sequentially arranged along a first light path direction, wherein the Fizeau interferometer is adaptive to the reflectivity of a detection surface to realize high interference contrast;
the imaging diaphragm, the imaging lens group and the ccd camera are sequentially arranged along the second light path direction;
the first light path direction is the same as the transmission optical axis direction of the polarization beam splitter, and the second light path direction is the same as the reflection optical axis direction of the polarization beam splitter;
the 1/2 wave plate is arranged on a rotating mechanism for adjusting the angle of the fast axis, the polarization direction of the transmitted light beam is changed by rotating the 1/2 wave plate, and finally, the energy attenuation of the transmitted light beam is realized by matching with the polarization beam splitter, and the attenuation proportion is continuously adjustable;
the incident light of the polarization reference lens group is linearly polarized light, the returned reference light is linearly polarized light, the polarization direction of the returned reference light is the same as that of the incident light, and the returned measurement light is linearly polarized light, and the polarization direction of the returned reference light is perpendicular to that of the incident light;
the returned reference light and the measuring light enter the Faraday rotator again and then synchronously rotate in the polarization direction, and then pass through the polarization beam splitter again; the reference light and the measuring light entering the polarization beam splitter have different polarization directions;
the imaging lens group images the reference light and the measuring light to the focal plane of the ccd camera and forms interference signals; the reference light and the measuring light at the focal plane of the ccd camera are linearly polarized light with the same polarization direction, and at this time, the contrast ratio of the interference signal is determined by the ratio of the reference light intensity to the measuring light intensity.
2. The Fizeau interferometer of claim 1 adapted to achieve high interference contrast with respect to the reflectivity of the detection surface, wherein: the rotation mechanism is an electric rotation mechanism.
3. The Fizeau interferometer of claim 1 adapted to achieve high interference contrast with respect to the reflectivity of the detection surface, wherein: the polarization reference lens group comprises a first medium, a reference surface, a second medium and an antireflection film which are sequentially arranged along the first light path direction;
the first medium is an amorphous optical medium;
the second medium is a birefringent crystalline optical medium.
4. A fizeau interferometer adapted to detect surface reflectivity for high interference contrast as claimed in claim 3, wherein: the second medium is a 1/4 wave plate.
5. A fizeau interferometer adapted to detect surface reflectivity for high interference contrast as claimed in claim 3, wherein: the first medium is fused quartz optical glass;
the second medium is magnesium fluoride birefringent crystal.
6. The Fizeau interferometer of claim 1 adapted to achieve high interference contrast with respect to the reflectivity of the detection surface, wherein: the illumination diaphragm is positioned at the focal position of the converging lens group, and the aperture of the illumination diaphragm is smaller than the theoretical Airy spot diameter of the converging lens group.
7. A fizeau interferometer adapted to detect surface reflectivity for high interference contrast as claimed in claim 3, wherein: the antireflection film is a multilayer antireflection film.
8. A fizeau interferometer adapted to detect surface reflectivity for high interference contrast as claimed in claim 3, wherein: the first medium is connected with the second medium through optical cement.
9. The Fizeau interferometer of claim 1 adapted to achieve high interference contrast with respect to the reflectivity of the detection surface, wherein: the polarization beam splitter transmits P polarized light and reflects S polarized light.
10. The Fizeau interferometer of claim 1 adapted to achieve high interference contrast with respect to the reflectivity of the detection surface, wherein: the polarization beam splitter comprises any one of a PBS optical film, a polarization diffraction device and a micro polarization element array.
CN202211639208.9A 2022-12-20 2022-12-20 Fizeau interferometer for realizing high interference contrast by adapting to reflectivity of detection surface Pending CN116105594A (en)

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