A wide spectrum Fizeau interferometer

Abstract

The present invention relates to a wide spectrum Fizeau interferometer, comprising: a tunable wavelength laser, equipped with a laser source capable of independently adjusting the emission wavelength, for emitting light of multiple wavelengths; a wire grid wide spectrum PBS spectrometer, directly receiving the light from the tunable wavelength laser, and reflecting the light. The present invention receives the circularly polarized light collimated from the front off-axis reflector through a plane standard mirror, and accurately reflects the light to a parabolic reflector, the geometric shape of the parabolic mirror enables it to focus the received light on one point, thereby achieving high-precision beam control, and at the same time the parabolic reflector also helps to correct the chromatic aberration caused by light of different wavelengths to a certain extent, thereby achieving the use of a reflective beam expansion optical system, eliminating the chromatic aberration problem caused by different wavelengths, and realizing the transmission wavefront measurement of an optical system with different wavelengths of a wide spectrum.

Description

Technical Field

[0001] The invention relates to the field of interferometers, and in particular to a wide-spectrum Fizeau interferometer. Background Art

[0002] The optical Fizeau interferometer is an optical instrument that uses the interference principle to measure the difference in optical paths and thus determine related physical quantities. Any change in the optical path difference between two coherent light beams will very sensitively cause the movement of interference fringes. The change in the optical path of a coherent light beam is caused by the change in the geometric path it passes through or the refractive index of the medium. Therefore, the interferometer measures the optical path difference in units of light wavelength, and its high measurement accuracy is unmatched by other measurement methods.

[0003] With the development of the optical field, the precision requirements for optical systems are getting higher and higher. The transmitted wavefront of many optical systems needs to reach the level of wave aberration. At this time, it is necessary to use an interferometer to measure the transmitted wavefront of the optical system. At present, Fizeau interferometers are basically Fizeau interferometers at a wavelength of 633nm. Therefore, for the transmitted wavefront of optical systems with wavelengths other than 633nm, traditional Fizeau interferometers cannot measure. There are also a few interferometers that are customized according to a special wavelength of the optical system. Once the optical system changes the design wavelength, the interferometer will not be able to measure. Due to the high cost of the interferometer, when measuring the transmitted wavefront of optical systems with different wavelengths, it is not practical to customize the interferometer for all optical systems with different wavelengths. Therefore, the present invention provides a wide-spectrum Fizeau interferometer measurement solution to meet the transmission wavefront measurement of all wavelength optical systems within a certain spectral range. . Summary of the invention

[0004] The object of the present invention is to provide a wide spectrum Fizeau interferometer.

[0005] In order to solve the above technical problems, the present invention provides a wide spectrum Fizeau interferometer, comprising:

[0006] Tunable wavelength lasers are equipped with a laser source that can independently adjust the emission wavelength and are used to emit light of multiple wavelengths;

[0007] A wire-grid wide spectrum PBS spectroscope directly receives light from a tunable wavelength laser and reflects the light;

[0008] Achromatic quarter wave plate, located in the reflective light path of the wire-grid wide spectrum PBS beam splitter, is used to convert the polarization state of the light passing through, so that the polarized light becomes circularly polarized light;

[0009] The front off-axis reflector receives the circularly polarized light processed by the achromatic quarter-wave plate and collimates the light to the standard mirror;

[0010] The standard mirror is located after the front off-axis reflector and is used to effectively reflect and focus light to support optical measurements of different numerical apertures;

[0011] The rear off-axis reflector and camera form an integral module, which receives the light beam transmitted by the wire-grid wide-spectrum PBS spectrometer. The module is movable along the optical axis to precisely adjust the focus and direct the light beam to the camera for detection.

[0012] The object to be measured receives the light transmitted by the standard mirror;

[0013] Standard reflector, used to reflect the light emitted by the object being measured,

[0014] After the light is reflected by the standard reflector, its transmitted wavefront information interferes with the reflected light information of the standard mirror;

[0015] The motion control acquisition system is used to control the position of various optical components including the laser, rear off-axis reflector and camera, and to acquire the interference fringe data generated by these components.

[0016] Furthermore, the standard mirror includes a plane standard mirror and a parabolic reflector, wherein the plane standard mirror is located behind the front off-axis reflector and first receives and reflects the light, and the parabolic reflector then receives the light reflected by the plane mirror and converges it.

[0017] Furthermore, the tunable wavelength laser is configured to be movable along the optical axis to compensate for light deflection caused by the achromatic quarter-wave plate and the wire-grid wide-spectrum PBS spectroscope, thereby ensuring that the light is correctly focused at different wavelengths.

[0018] Furthermore, the achromatic quarter wave plate and the wire-grid wide spectrum PBS spectroscope are both made of the same optical material.

[0019] Furthermore, the position adjustment of the module consisting of the rear off-axis reflector and the camera and the tunable wavelength laser is based on pre-calibrated data to compensate for the chromatic aberration and focal plane change caused by the achromatic quarter-wave plate and the PBS beam splitter.

[0020] Furthermore, the achromatic quarter wave plate and the wire grid wide spectrum PBS spectrometer have different refractive indices n1 and n2 at different wavelengths λ1 and λ2, and the total thickness of the achromatic quarter wave plate and the wire grid wide spectrum PBS spectrometer is d. They are configured to adjust the angle Θ of the incident light according to the refractive index formula sinΘ*n0=sinΘ1*n1 under different media, so that the light deflection angle at wavelength λ1 is Θ1, and the light deflection angle at wavelength λ2 is Θ2. The focal position at different wavelengths is calibrated and recorded by calculating the focal plane deviation z=(d*tanΘ2-d*tanΘ1) / tanΘ.

[0021] Furthermore, the motion control acquisition system has an automatic adjustment function, which can automatically adjust the position of the optical components according to preset calibration data, and process the collected interference fringe images to obtain the transmitted wavefront information of the object under test. The motion control acquisition system controls the position of the module composed of the rear off-axis reflector and the camera and the tunable wavelength laser to ensure the best interference effect at different wavelengths and record the detailed information of the interference fringes.

[0022] Furthermore, the plane standard mirror and the parabolic reflector are movable mirrors for accurately adjusting the relative position between the plane standard mirror and the parabolic reflector.

[0023] Furthermore, the parabolic reflector is manufactured by high-precision processing technology, the shape tolerance of the reflector surface is controlled within ±λ / 20, and the surface roughness Ra value does not exceed 1 nanometer, which is used to reduce the measurement error caused by the parabolic reflector.

[0024] The present invention also provides a wide spectrum Fizeau interferometer measurement method, comprising the following steps:

[0025] S1: The tunable wavelength laser emits light with a certain field angle and adjusts the polarization direction of the laser to ensure that the light can correctly reflect the polarized light after passing through the wire-grid wide spectrum PBS spectrometer;

[0026] S2: The light passing through the wire-grid wide-spectrum PBS beamsplitter is converted into circularly polarized light by an achromatic quarter-wave plate, then collimated by a front off-axis reflector and irradiated onto the reference surface of the standard mirror;

[0027] S3: A part of the light is reflected by the reference surface of the standard mirror and returns to the achromatic quarter-wave plate through the front off-axis reflector, so that the polarization state of the light becomes perpendicular to the incident light; the light then passes through the wire-grid wide-spectrum PBS spectrometer and enters the camera through the rear off-axis reflector; another part of the light passes through the standard mirror, irradiates the object to be measured, and is then reflected by the standard reflector. The reflected light follows the same optical path of the light reflected by the reference surface of the standard mirror and finally enters the camera. The standard mirror includes a plane standard mirror and a parabolic reflector.

[0028] S4: The transmitted wavefront information of the object being measured and the reflected light information of the standard mirror reference surface interfere with each other in the camera, generating interference fringes;

[0029] S5: Use the motion control acquisition system to process and collect the interference fringe information in phase shift terms; analyze the collected interference fringes through the data processing algorithm, and calculate and obtain the transmission wavefront information of the object under test.

[0030] The beneficial effect of the present invention is that the present invention receives the circularly polarized light collimated from the front off-axis reflector through a plane standard mirror, and accurately reflects the light to the parabolic reflector without changing the direction of the light. The parabolic reflector receives the light reflected from the plane standard mirror. The geometric shape of the parabolic mirror enables it to focus the received light on one point, thereby achieving high-precision beam control. Through this two-stage reflector setting, the system can provide extremely high optical accuracy. At the same time, the parabolic reflector also helps to correct the chromatic aberration caused by light of different wavelengths to a certain extent, thereby achieving the use of a reflective beam expansion optical system to eliminate the chromatic aberration problem caused by different wavelengths and realize the transmission wavefront measurement of an optical system with different wavelengths in a wide spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1 is a flow chart of the beam expansion system of the object under test of the present invention;

[0033] Figure 2 is a flow chart of the imaging system of the object to be measured of the present invention;

[0034] Figure 3 It is a schematic diagram of light refraction and focus shift of the present invention.

[0035] In the figure:

[0036] 101. Standard reflector; 201. Standard mirror; 211. Plane standard mirror; 212. Parabolic reflector; 3. Front off-axis reflector; 4. Achromatic quarter-wave plate; 5. Wire-grid wide-spectrum PBS spectrometer; 6. Rear off-axis reflector; 7. Camera; 8. Motion control acquisition system; 9. Tunable wavelength laser; 1001. Object to be measured. DETAILED DESCRIPTION

[0037] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0038] like Figure 1-3As shown, a wide spectrum Fizeau interferometer of the present invention comprises: a tunable wavelength laser 9, which is equipped with a laser source capable of independently adjusting the emission wavelength and is used to emit light of multiple wavelengths; a wire-grid wide spectrum PBS spectroscope 5, which directly receives the light from the tunable wavelength laser 9 and reflects the light; an achromatic quarter-wave plate 4, which is located in the reflection light path of the wire-grid wide spectrum PBS spectroscope 5 and is used to convert the polarization state of the light passing through and convert the polarized light into circularly polarized light; a front off-axis reflector 3, which receives the circularly polarized light processed by the achromatic quarter-wave plate 4 and collimates the light to irradiate the standard mirror 201; the standard mirror 201, which is located behind the front off-axis reflector 3 and is used to effectively reflect and converge the light. To support optical measurement of different numerical apertures; the rear off-axis reflector 6 and the camera 7 form an integral module, which receives the light beam transmitted by the wire-grid wide-spectrum PBS spectrometer 5, and the module is movable along the optical axis to accurately adjust the focus and guide the light beam to the camera 7 for detection; the object under test 1001 receives the light transmitted by the standard mirror 201; the standard reflector 101 is used to reflect the light emitted by the object under test 1001, wherein after the light is reflected by the standard reflector 101, its transmitted wavefront information interferes with the reflected light information of the standard mirror 201; the motion control acquisition system 8 is used to control the position of each optical component including the laser, the rear off-axis reflector 6 and the camera 7, and to collect the interference fringe data generated by these components.

[0039] According to the selected light source wavelength, the tunable wavelength laser 9 is moved to the calibration position in advance, and the rear off-axis reflector 6 and the camera 7 are also moved to the calibration position. The tunable wavelength laser 9 emits light with a certain field of view angle, and the polarization state direction of the tunable wavelength laser 9 is adjusted to ensure that the polarized light can reflect the polarized light after passing through the wire grid wide spectrum PBS spectrometer 5. The light is then converted into circularly polarized light through the achromatic quarter wave plate 4, and then collimated through the front off-axis reflector 3 to irradiate the reference surface of the standard mirror 201. A part of the light is reflected by the reference surface of the standard mirror 201, and after passing through the front off-axis reflector 3 and the achromatic quarter wave plate 4, the polarization state of the light becomes polarized light perpendicular to the incident light of the tunable wavelength laser 9. The light is transmitted through the wire grid type The wide spectrum PBS beam splitter 5 passes through the rear off-axis reflector 6 and enters the camera 7. Another part of the light irradiated on the reference surface of the standard mirror 201 passes through the standard mirror 201 and irradiates the object 1001 to be measured and then reflects through the standard reflector 101. The light enters the camera 7 along the same optical path as the standard surface of the standard mirror 201. The transmission wavefront information of the object 1001 and the reflected light information of the reference surface of the standard mirror 201 interfere with each other to generate fringes. The interferometer information is shifted and collected through the motion control acquisition system 8, and data processing is performed to obtain the transmission wavefront information of the object 1001 to be measured, thereby achieving the use of a reflective beam expansion optical system to eliminate the chromatic aberration problem caused by different wavelengths and realize the transmission wavefront measurement of the optical system with wide spectrum and different wavelengths.

[0040] The object to be measured 1001 is generally an optical system such as a beam expansion system, a focusing system or an imaging system. Figure 1 and Figure 2 Two examples are shown, in which the object to be measured 1001 is a beam expansion system and the object to be measured 1001 is an imaging system, but the measurement scope of the present invention should not be limited thereby.

[0041] The standard mirror 201 includes a plane standard mirror 211 and a parabolic reflector 212, wherein the plane standard mirror 211 is located behind the front off-axis reflector 3, and first receives and reflects the light, and the parabolic reflector 212 then receives the light reflected by the plane mirror and converges it.

[0042] The plane standard mirror 211 is located after the optical path of the front off-axis reflector 3. It is the first component in the system to receive the circularly polarized light collimated from the front off-axis reflector 3. Its main function is to reflect light. Due to its planar characteristics, it can accurately reflect the light to the next optical component, namely the parabolic reflector 212, without changing the direction of the light. The parabolic reflector 212 receives the light reflected from the plane standard mirror 211. This mirror has a focusing effect on the light due to its parabolic shape. The geometric shape of the parabolic mirror enables it to focus the received light on one point, thereby achieving high-precision beam control. Through this two-stage reflector setting, the system can provide extremely high optical accuracy. At the same time, the parabolic reflector 212 also helps to correct the chromatic aberration caused by light of different wavelengths to a certain extent.

[0043] The tunable wavelength laser 9 is configured to be movable along the optical axis to compensate for the light deflection caused by the achromatic quarter-wave plate 4 and the wire-grid wide-spectrum PBS spectrometer 5, thereby ensuring that the light is correctly focused at different wavelengths.

[0044] The tunable wavelength laser 9 is designed to be able to move precisely along the optical axis. This mobility allows the laser to adjust its position according to different measurement requirements to ensure that the light is always on the optimal optical path.

[0045] The module consisting of the rear off-axis reflector 6 and the camera 7 and the position adjustment of the tunable wavelength laser 9 are based on pre-calibrated data to compensate for the chromatic aberration and focal plane changes caused by the achromatic quarter-wave plate 4 and the PBS spectroscope.

[0046] When light of different wavelengths passes through the achromatic quarter-wave plate 4 and the wire-grid wide-spectrum PBS spectrometer 5, these components will have a small but significant impact on the propagation path of the light, which is mainly manifested as changes in chromatic aberration and focal plane position. In order to compensate for these changes, calibration will be performed for each wavelength during the initial setting, and the optimal laser position at each wavelength and the position data of the rear off-axis reflector 6 and camera 7 modules will be recorded. The adjustment of the laser position ensures that the light can maintain the best focus state at each wavelength. The module composed of the rear off-axis reflector 6 and camera 7 can also automatically adjust the position according to the calibration data. This adjustment can compensate for the focal plane deviation caused by light of different wavelengths passing through the achromatic quarter-wave plate 4 and the PBS spectrometer, ensuring that the light can accurately reach the sensor of the camera 7 and achieve clear interference image capture.

[0047] The achromatic quarter wave plate 4 and the wire grid wide spectrum PBS spectroscope 5 are both made of the same optical material. The achromatic quarter wave plate 4 and the wire grid wide spectrum PBS spectroscope 5 have different refractive indices n1 and n2 at different wavelengths λ1 and λ2. The total thickness of the achromatic quarter wave plate 4 and the wire grid wide spectrum PBS spectroscope 5 is d. They are configured to adjust the angle Θ of the incident light according to the refractive index formula sinΘ*n0=sinΘ1*n1 under different media, so that the light deflection angle at wavelength λ1 is Θ1, and the light deflection angle at wavelength λ2 is Θ2. The focal position at different wavelengths is calibrated and recorded by calculating the focal plane deviation z=(d*tanΘ2-d*tanΘ1) / tanΘ.

[0048] According to the refractive index formula sinΘ*n0=sinΘ1*n1 under different media, where n0 is the refractive index of air, the angle Θ of the incident light and the corresponding refraction angle can be calculated, ensuring that the propagation path of the light can be accurately controlled at different wavelengths. The total thickness of the achromatic quarter-wave plate 4 and the wire-grid wide-spectrum PBS spectrometer 5 is d. By calculating the focal plane deviation z=(d*tanΘ2-d*tanΘ1) / tanΘ, the focal position at different wavelengths can be accurately calibrated and recorded, so that the system can pre-set the optimal focus at each wavelength to ensure that the light can be correctly focused at different wavelengths.

[0049] Assuming that the aperture D1 of the front off-axis reflector 3 is 100 mm, the focal length f1 is 500 mm, and the aperture D2 of the rear off-axis reflector 6 is 10 mm, and the focal length f2 is 50 mm, then the numerical aperture NA of the front off-axis reflector 3 is n0*sinΘ=D1 / 2 / f1=50 / 500=0.1, where n0=1 is the refractive index of air, and sinΘ is the sin value of the maximum convergence angle of the front off-axis reflector 3.

[0050] Assume that the materials of the achromatic quarter-wave plate 4 and the wire-grid wide-spectrum PBS spectrometer 5 are Chengdu Guangming Optical Material K9, with a total thickness of d=30mm, and the test wavelengths of the two interferometers are λ1=550nm and λ2=633nm, respectively. At the two wavelengths, the refractive indices of the optical material k9 are n1=1.518721 and n2=1.515092, respectively. According to the formulas sinΘ*n0=sinΘ2*n2 and z=(d*tanΘ2-d*tanΘ1) / tanΘ, it can be calculated that Z=0.047386mm.

[0051] From this, we can see that if we calibrate the position of the tunable wavelength laser 9, the rear off-axis reflector 6 and the camera 7 to zero when measuring at a wavelength of λ1=550nm, then when we need to switch from measuring the optical system transmitted wavefront at a wavelength of λ1=550nm to measuring the optical system transmitted wavefront at a wavelength of λ2=633nm, we only need to move the position of the tunable wavelength laser 9, the rear off-axis reflector 6 and the camera 7 by Z=0.047386mm along the optical axis, and switch the wavelength of the tunable wavelength laser 9 to 633nm, and then we can measure the optical system transmitted wavefront at a wavelength of 633nm. Therefore, the transmission wavefront of optical systems with different wavelengths can be measured, thereby achieving the purpose of performing wide-spectrum interferometry measurement with one interferometer.

[0052] The motion control acquisition system 8 has an automatic adjustment function, which can automatically adjust the position of the optical components according to the preset calibration data, and process the collected interference fringe images to obtain the transmission wavefront information of the object 1001 under test. The motion control acquisition system 8 controls the position of the module composed of the rear off-axis reflector 6 and the camera 7 and the tunable wavelength laser 9 to ensure the best interference effect at different wavelengths and record the detailed information of the interference fringes.

[0053] The plane standard mirror 211 and the parabolic reflector 212 are movable mirrors for precisely adjusting the relative position between the plane standard mirror 211 and the parabolic reflector 212 .

[0054] The motion control acquisition system 8 can automatically adjust the position of each optical component in the interferometer according to the pre-calibrated data, including the precise control of the module composed of the rear off-axis reflector 6 and the camera 7 and the position of the tunable wavelength laser 9, so as to ensure that these components are in the best position at different wavelengths. By automatically adjusting the position of the optical components to meet the measurement requirements of different wavelengths, this function eliminates the complexity and potential errors of manual adjustment and improves the speed and consistency of measurement.

[0055] The parabolic reflector 212 is manufactured by high-precision processing technology. The shape tolerance of the reflector surface is controlled within ±λ / 20, and the surface roughness Ra value does not exceed 1 nanometer, which is used to reduce the measurement error caused by the parabolic reflector 212.

[0056] The present invention also provides a wide spectrum Fizeau interferometer measurement method, comprising the following steps:

[0057] S1: The tunable wavelength laser 9 emits light with a certain field angle and adjusts the polarization direction of the laser to ensure that the light can correctly reflect polarized light after passing through the wire-grid wide spectrum PBS spectroscope 5;

[0058] S2: The light passing through the wire-grid wide-spectrum PBS beam splitter 5 is converted into circularly polarized light by the achromatic quarter-wave plate 4, then collimated by the front off-axis reflector 3, and irradiated onto the reference surface of the standard mirror 201;

[0059] S3: A portion of the light is reflected by the reference surface of the standard mirror 201, and returns to the achromatic quarter-wave plate 4 through the front off-axis reflector 3, so that the polarization state of the light becomes perpendicular to the incident light; the light then passes through the wire-grid wide-spectrum PBS spectrometer 5, and enters the camera 7 through the rear off-axis reflector 6; another portion of the light passes through the standard mirror 201, irradiates the object to be measured 1001, and is then reflected by the standard reflector 101. The reflected light follows the same optical path of the light previously reflected by the reference surface of the standard mirror 201, and finally enters the camera 7, wherein the standard mirror 201 includes a plane standard mirror 211 and a parabolic reflector 212;

[0060] S4: The transmitted wavefront information of the object 1001 and the reflected light information of the reference surface of the standard mirror 201 interfere with each other in the camera 7, generating interference fringes;

[0061] S5: using the motion control acquisition system 8 to process and acquire the interference fringe information in phase shift terms; analyzing the acquired interference fringes through a data processing algorithm, and calculating and acquiring the transmission wavefront information of the object under test 1001 .

[0062] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A wide spectrum Fizeau interferometer, characterized in that: include: A tunable wavelength laser (9) is provided with a laser source capable of independently adjusting the emission wavelength, and is used to emit light of multiple wavelengths; A wire-grid wide spectrum PBS spectroscope (5) directly receives light from the tunable wavelength laser (9) and reflects the light; An achromatic quarter wave plate (4) is located in the reflection light path of the wire grid wide spectrum PBS spectroscope (5) and is used to convert the polarization state of the light passing through so that the polarized light becomes circularly polarized light; A front off-axis reflector (3) receives the circularly polarized light processed by the achromatic quarter-wave plate (4) and collimates the light to irradiate the standard mirror (201); A standard mirror (201), located behind the front off-axis reflector (3), used for effectively reflecting and converging light to support optical measurements of different numerical apertures; The rear off-axis reflector (6) and the camera (7) form an integral module, which receives the light beam transmitted by the wire-grid wide-spectrum PBS spectroscope (5), and the module is movable along the optical axis to accurately adjust the focus and guide the light beam to the camera (7) for detection; The object to be measured (1001) receives the light transmitted by the standard mirror (201); The standard reflector (101) is used to reflect the light emitted by the object to be measured (1001), wherein After the light is reflected by the standard reflector (101), its transmitted wavefront information interferes with the reflected light information of the standard mirror (201); A motion control acquisition system (8), the motion control acquisition system (8) being connected to the camera (7) and used to control the positions of various optical components including a laser, a rear off-axis reflector (6) and a camera (7), and to acquire interference fringe data generated by these components; The achromatic quarter-wave plate (4) and the wire-grid wide-spectrum PBS spectroscope (5) are both made of the same optical material; The module composed of the rear off-axis reflector (6) and the camera (7) and the position adjustment of the tunable wavelength laser (9) are based on pre-calibrated data to compensate for the chromatic aberration and focal plane change caused by the achromatic quarter-wave plate (4) and the PBS beam splitter; The achromatic quarter wave plate (4) and the wire grid wide spectrum PBS spectroscope (5) have different refractive indices n1 and n2 at different wavelengths λ1 and λ2. The total thickness of the achromatic quarter wave plate (4) and the wire grid wide spectrum PBS spectroscope (5) is d. The achromatic quarter wave plate (4) and the wire grid wide spectrum PBS spectroscope (5) are configured to adjust the angle Θ of the incident light according to the refractive index formula sinΘ*n0=sinΘ1*n1 under different media, so that the light deflection angle at the wavelength λ1 is Θ1, and the light deflection angle at the wavelength λ2 is Θ2. The focal position at different wavelengths is calibrated and recorded by calculating the focal plane deviation z=(d*tanΘ2-d*tanΘ1) / tanΘ.

2. A wide spectrum Fizeau interferometer as claimed in claim 1, characterized in that: The standard mirror (201) comprises a plane standard mirror (211) and a parabolic reflector (212), wherein the plane standard mirror (211) is located behind the front off-axis reflector (3) and first receives and reflects light, and the parabolic reflector (212) then receives and converges the light reflected by the plane mirror.

3. A wide spectrum Fizeau interferometer as claimed in claim 2, characterized in that: The tunable wavelength laser (9) is configured to be movable along the optical axis direction, and is used to compensate for light deflection caused by the achromatic quarter-wave plate (4) and the wire-grid wide-spectrum PBS spectroscope (5), thereby ensuring that the light is correctly focused at different wavelengths.

4. A wide spectrum Fizeau interferometer as claimed in claim 3, characterized in that: The motion control acquisition system (8) has an automatic adjustment function, and can automatically adjust the position of the optical component according to preset calibration data, and process the collected interference fringe image to obtain the transmission wavefront information of the object to be measured (1001), wherein the position of the module composed of the rear off-axis reflector (6) and the camera (7) and the tunable wavelength laser (9) is controlled by the motion control acquisition system (8) to ensure that the best interference effect is obtained at different wavelengths, and the detailed information of the interference fringes is recorded.

5. A wide spectrum Fizeau interferometer as claimed in claim 4, characterized in that: The plane standard mirror (211) and the parabolic reflector (212) are movable mirrors, and are used to accurately adjust the relative position between the plane standard mirror (211) and the parabolic reflector (212).

6. A wide spectrum Fizeau interferometer as claimed in claim 5, characterized in that: The shape tolerance of the surface of the parabolic reflector (212) is controlled within ±λ / 20, and the surface roughness Ra value does not exceed 1 nanometer, so as to reduce the measurement error caused by the parabolic reflector (212).

7. A wide spectrum Fizeau interferometer measurement method, based on the wide spectrum Fizeau interferometer according to claim 6, characterized in that: S1: The tunable wavelength laser (9) emits light with a certain field angle and adjusts the polarization direction of the laser to ensure that the light can correctly reflect polarized light after passing through the wire grid wide spectrum PBS spectroscope (5); S2: The light passing through the wire-grid wide-spectrum PBS spectroscope (5) is converted into circularly polarized light by the achromatic quarter-wave plate (4), then collimated by the front off-axis reflector (3), and irradiated onto the reference surface of the standard mirror (201); S3: A portion of the light is reflected by the reference surface of the standard mirror (201) and returns to the achromatic quarter-wave plate (4) through the front off-axis reflector (3), so that the polarization state of the light changes to a polarization state perpendicular to the incident light; the light then passes through the wire-grid wide-spectrum PBS spectrometer (5) and enters the camera (7) through the rear off-axis reflector (6); another portion of the light passes through the standard mirror (201), irradiates the object to be measured (1001), and is then reflected by the standard reflector (101). The reflected light follows the same optical path of the light previously reflected by the reference surface of the standard mirror (201), and finally enters the camera (7), wherein the standard mirror (201) includes a plane standard mirror (211) and a parabolic reflector (212); S4: The transmitted wavefront information of the object to be measured (1001) and the reflected light information of the reference surface of the standard mirror (201) interfere with each other in the camera (7), generating interference fringes; S5: using the motion control acquisition system (8) to process and acquire the interference fringe information in terms of phase shift; analyzing the acquired interference fringes through a data processing algorithm, and calculating and acquiring the transmission wavefront information of the object under test (1001).

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