Large-aperture anti-interference interference detection device based on Michelson interference architecture

Abstract

The invention relates to a large-aperture anti-interference interference detection device based on a Michelson interference architecture. The large-aperture anti-interference interference detection device comprises a light beam shaping module, an interference assembly and an imaging assembly, the interference assembly comprises a first quarter-wave plate, a first polarization splitting prism, a second quarter-wave plate, a second polarization splitting prism, a third quarter-wave plate and a concave reflector which are arranged on a main light path; a fourth quarter-wave plate and an optical flat are arranged on a sample arm light path of the second polarization splitting prism; and a plane mirror is arranged on a reference arm light path of the second polarization splitting prism. According to the invention, interference detection data of a to-be-detected sample in a high-dynamic environment is obtained in a dynamic self-compensation mode; interference fringe information is obtained through transmission of the large-aperture imaging assembly; the problems of phase noise and interference contrast reduction induced by environmental disturbance are eliminated; the method can be used for high-precision surface type detection of a to-be-detected sample with a reflecting surface characteristic, and is particularly suitable for resonant cavities such as a disc laser with a jitter air wedge characteristic and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of precision optical interferometry in a high-dynamic environment, and in particular to a large-aperture anti-interference interference detection device based on a Michelson interferometer architecture. Background Art

[0002] Conventional interferometry systems employ an open optical path with a low lens count. While this simplifies the optical calibration process, it exposes the reference and sample arms to environmental disturbances. When the measurement environment is subject to thermally induced refractive index disturbances (such as the dynamic temperature gradient within a disk laser resonator) or mechanical vibration, the interference fringe phase stability can fluctuate by at least 0.05λ. In high-energy laser systems, air wedge jitter caused by cavity thermal deformation can cause interference contrast to drop by more than 40%. Existing anti-interference solutions often rely on passive suppression strategies, such as forced convection and mechanical vibration isolation, as discussed in "Suppression of instability of output beam of thin-disk lasers caused by the air-wedge effect based on resonator design." However, when these solutions are applied to high-energy resonators, active airflow can easily contaminate the optical components within the cavity. Mechanical vibration isolation platforms can only ensure the overall stability of the laser platform (at low frequencies), which has certain limitations. Therefore, to meet the requirements for real-time compensation in the highly dynamic environment of high-energy resonators, a common-optical-path interferometry detection method and device are proposed.

[0003] The document with the announcement number "CN 112147080 B" discloses the "Free-space Mueller OCT Imaging System and Imaging Method with Fully Automatic Time-Division Detection". There are four optical channels with different polarization types in the reference arm: horizontal, vertical, 45° linear polarization, and right-hand circular polarization. The sample arm uses a software program to control the precision rotating worktable to rotate the wave plate to achieve these four states of polarized light. The reference arm is used to control the optical switch to select different channels in the reference arm. The polarized light of each channel is returned and interferes with the polarized light scattered back by the sample arm, thereby realizing time-division detection of polarization information. Existing problems: The sample arm and the reference arm are independent of each other. The sample to be tested is easily affected by the high dynamic environment, and there are problems such as phase noise induced by environmental disturbances and reduced interference contrast. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art in phase noise induced by environmental disturbances and decreased interference contrast, the purpose of the present invention is to provide a large-aperture anti-interference interference detection device based on a Michelson architecture.

[0005] In order to achieve the above-mentioned object, the technical solution of the present invention is: a large-aperture anti-interference interference detection device based on the Michelson interferometer architecture, comprising a beam shaping module, an interference component and an imaging component;

[0006] The interference assembly includes a first quarter-wave plate, a first polarization beam splitter prism, a second quarter-wave plate, a second polarization beam splitter prism, a third quarter-wave plate, and a concave reflector arranged in sequence on the main optical path; a fourth quarter-wave plate and an optical flat crystal are arranged in sequence on the sample arm optical path of the second polarization beam splitter prism, and a plane reflector is arranged in sequence on the reference arm optical path of the second polarization beam splitter prism.

[0007] Furthermore, the above-mentioned imaging component includes a front group first lens, a front group second lens and a reflector located on the reflected light path of the first polarization splitter prism, and an aperture, a rear group first lens, a rear group second lens and an imaging camera are arranged on the reflected light path of the reflector.

[0008] Furthermore, the beam shaping module is composed of a polarized light source including a collimating lens and a shaping lens.

[0009] Furthermore, the concave reflector includes a spherical reflector, an aspherical reflector or a parabolic reflector.

[0010] Furthermore, the concave reflector is a spherical reflector.

[0011] Furthermore, the concave reflector can fine-tune the distance between its focus and the sample to be measured along the optical axis, and the adjustment device includes but is not limited to a translation stage and a multi-axis adjustable mirror frame.

[0012] Furthermore, the above-mentioned optical flat crystal adjusts its displacement to match the optical path through a pointing and displacement adjustment device, and adjusts the inclination angle between its optical axis and the normal of the surface of the sample to be measured to be greater than 0 degrees and less than 0.5 degrees. The adjustment device includes but is not limited to a translation stage, a multi-axis mirror frame and a driving ceramic.

[0013] Furthermore, the focal length f1 of the above-mentioned first lens of the front group and the focal length f2 of the second lens of the front group satisfy the relationship: -0.58<f1 / f2<-0.69, the focal length f3 of the first lens of the rear group and the focal length f4 of the second lens of the rear group satisfy the relationship: -1.8<f3 / f4<-2.9, and the total focal length fg1 of the front lens group and the total focal length fg2 of the rear lens group satisfy the relationship: 0.99<fg1 / fg2<1.01; the first lens of the front group, the second lens of the front group, the first lens of the rear group, and the second lens of the rear group share the same optical axis, forming a "positive-negative-negative-positive" lens sequence, the first lens of the front group and the second lens of the rear group have positive focal lengths, and the second lens of the front group and the first lens of the rear group have negative focal lengths.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] 1. The core structure of the present invention is to integrate the optical path components of the sample arm and the reference arm into the same physical space, allowing both arms to pass through a high-dynamic environment together, eliminating the phase noise and interference contrast degradation induced by environmental disturbances. The present invention is based on a large-aperture interferometer with a Michelson interferometer architecture, and its structural improvements include:

[0016] (1) Optical path of the sample arm: The sample light is controlled to enter the common optical path area by passing through the quarter-wave plate twice, that is, the high dynamic range where the sample to be measured is located. The light returning from the sample to be measured carries the sample surface information, passes through the quarter-wave plate twice, and then exits the prism.

[0017] (2) Reference arm optical path: The reference light is controlled by passing through a quarter-wave plate twice to enter the common optical path region, i.e., the high dynamic range where the sample to be measured is located. The initial reference light is parallel light and is focused onto the surface of the sample to be measured by a concave reflector. The focus does not carry any information about the sample surface. After passing through the quarter-wave plate twice, it is emitted from the prism. In this process, the concave reflector and the sample to be measured form a 4F system that can reproduce the incident wavefront distribution, i.e., it does not carry any information about the sample.

[0018] In summary, the device of the present invention cleverly utilizes the common optical path structure to obtain interference detection data of the sample to be tested in a high dynamic environment through dynamic self-compensation; and obtains interference fringe information through large-aperture imaging components.

[0019] 2. The present invention can be used for high-precision surface detection of samples with reflective surface characteristics, and is particularly suitable for resonant cavities such as disk lasers with jitter air wedge characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the optical path of an interference detection device according to some embodiments of the present invention;

[0021] Figure 2 for Figure 1 Schematic diagram of the optical path of the reference arm of the illustrated embodiment;

[0022] Figure 3 for Figure 1 Schematic diagram of the optical path of the sample arm of the illustrated embodiment;

[0023] Figure 4 for Figure 1 A schematic diagram of the optical path of the imaging system of the illustrated embodiment;

[0024] Figure 5 for Figure 1 Wavefront phase difference diagram of the imaging system of the illustrated embodiment;

[0025] Figure 6 is a schematic diagram of a correction process of an interference detection method according to some embodiments of the present invention;

[0026] Wherein, the reference numerals:

[0027] 1-beam shaping module; 11-polarized light source with collimating lens; 12-shaping lens group; 2-interference component; 21-first quarter-wave plate; 22-first polarization beam splitter prism; 23-second quarter-wave plate; 24-second polarization beam splitter prism; 25-third quarter-wave plate; 26-concave reflector; 27-fourth quarter-wave plate; 28-optical flat crystal; 29-plane reflector; 210-sample to be measured; 3-imaging component; 31-first lens of the front group; 32-second lens of the front group; 33-reflector; 34-aperture; 35-first lens of the rear group; 36-second lens of the rear group; 37-imaging camera. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0029] The present invention provides an interference detection device, which transmits the light beam from the beam shaping module 1 to the interference component 2, carrying the wavefront information of the sample surface and the reference surface, and then transmits the interference image of the wavefront to the sensor for subsequent processing through the large-aperture imaging component 3.

[0030] See also Figure 1 The present invention provides a large-aperture, anti-interference interferometric detection device based on a Michelson interferometer architecture, comprising a beam shaping module 1, an interferometer assembly 2, and an imaging assembly 3. The beam shaping module 1 emits parallel light at the detection wavelength, which is incident on the interferometer assembly 2. The interferometer assembly 2 controls the sample light and reference light to enter a common optical path region, respectively, through a combination of a prism and a quarter-wave plate. The sample light carrying sample information interferes with the reference light, which maintains the incident wavefront through a 4F system, and the interference image is transmitted to the imaging assembly 3. The imaging assembly 3 transmits the interference image to the sensor for subsequent processing via a four-element, low-wavefront aberration transmission system.

[0031] The beam shaping module 1 can generate parallel light, and any structure capable of generating parallel light can be used. For example, it can be composed of a diffuse light source, a spatial aperture, and a collimating lens sequentially arranged along the light path. Alternatively, the structure of this embodiment can be used, consisting of a polarized light source 11 including a collimating lens and a shaping lens assembly 12.

[0032] The interference assembly 2 includes a first quarter-wave plate 21, a first polarization beam splitter prism 22, a second quarter-wave plate 23, a second polarization beam splitter prism 24, a third quarter-wave plate 25, and a concave reflector 26, which are sequentially arranged on the main optical path. A fourth quarter-wave plate 27 and an optical flat crystal 28 are sequentially arranged on the sample arm optical path of the second polarization beam splitter prism 24, and a plane reflector 29 is sequentially arranged on the reference arm optical path of the second polarization beam splitter prism 24. The interference assembly 2 includes a common optical path for the sample arm, the reference arm, and the sample to be measured 210. The reference surface at the end of the reference arm is a concave reflector 26, with its focus located on the surface of the sample to be measured 210 in the common optical path. The light beams transmitted by the sample arm and the reference arm respectively pass through the portion of the common optical path where the sample to be measured 210 is located before being transmitted to the imaging assembly 3, thereby obtaining a self-compensated interference image.

[0033] The concave reflector 26 is a high-precision concave reflector, including but not limited to a spherical reflector, an aspherical reflector, a parabolic reflector, etc. In this embodiment, a spherical reflector is preferably used.

[0034] The imaging assembly 3 includes a front first lens group 31, a front second lens group 32, and a reflector 33, which are located on the light path reflected by the first polarization beam splitting prism 22. The reflector 33 also includes an aperture 34, a rear first lens group 35, a rear second lens group 36, and an imaging camera 37. The imaging assembly 3 forms a low-wavefront-aberration bi-telecentric imaging system.

[0035] The concave reflector can fine-tune the distance between its focus and the sample 210 to be measured along the optical axis, and the adjustment device includes but is not limited to a translation stage, a multi-axis adjustable mirror frame, etc.

[0036] The optical flat crystal 28 is a high-precision plane reflector with a surface accuracy of not less than 1 / 20 wavelength. The optical flat crystal 28 is adjusted to match the optical path through a pointing and displacement adjustment device, and the inclination angle between its optical axis and the surface normal of the sample 210 to be measured is adjusted to be greater than 0 degree and less than 0.5 degree. The adjustment device includes but is not limited to a translation stage, a multi-axis mirror frame, a driving ceramic, etc.

[0037] Working principle:

[0038] The sample to be measured 210 is placed in the reflected light path of the plane reflector 29. The parallel polarized light beam incident on the interference element 2 passes through the first quarter-wave plate 21 and the first polarization beam splitter prism 22. By adjusting the intensity of the horizontal polarized light beam transmitted through the polarization beam splitter prism 22, the incident light after passing through the second quarter-wave plate 23 is formed into a circularly polarized light beam or an elliptically polarized light beam as required.

[0039] Please refer to Figure 2In this embodiment, after the circularly polarized light beam passes through the second polarization beam splitter prism 24, the transmitted light becomes horizontally polarized light. After the light beam is transmitted to the third quarter-wave plate 25 and concave reflector 26, it is transmitted back to the third quarter-wave plate 25 again, becoming vertically polarized light. After passing through the second polarization beam splitter prism 24 for the second time, the vertically polarized light beam is reflected and transmitted to the plane reflector 29 before entering the sample 210 to be tested.

[0040] Here, the parallel light beam incident on the concave reflector 26 is focused onto the surface of the sample to be tested 210; it is diverged and reflected back to the plane reflector 29 and the second polarization splitter prism 24 by the sample to be tested 210; after passing through the second polarization splitter prism 24 for the third time, the light beam is again transmitted to the third quarter-wave plate 25 and the concave reflector 26 and reflected back to the third quarter-wave plate 25, where the light beam is converted from vertical polarization to horizontal polarization, and is transmitted after passing through the second polarization splitter prism 24 for the fourth time; here, the divergent light beam from the surface of the sample to be tested 210 is collimated into a parallel light beam after passing through the concave reflector 26 and is transmitted through the polarization splitter prism 24.

[0041] The focal length of the concave reflector 26 is the optical path length of a+b+c.

[0042] Please refer to Figure 3 After the circularly polarized light beam passes through the second polarization splitter prism 24, the reflected light is vertically polarized light. After the light beam is transmitted to the fourth quarter-wave plate 27 and the optical flat crystal 28, the light beam is transmitted to the fourth quarter-wave plate 27 again, and the light beam is horizontally polarized light. After passing through the second polarization splitter prism 24 for the second time, the light beam is reflected and transmitted to the plane reflector 29 and the sample to be measured 210.

[0043] Here, the parallel light beam incident on the optical flat crystal 28 is transmitted to the surface of the sample to be measured 210; it is reflected back to the plane reflector 29 and the second polarization beam splitter prism 24 by the sample to be measured 210; after passing through the second polarization beam splitter prism 24 for the third time, the light beam is again transmitted to the fourth quarter-wave plate 27 and the optical flat crystal 28 and reflected back to the fourth quarter-wave plate 27, where the light beam is converted from horizontal polarization to vertical polarization, and is reflected after passing through the second polarization beam splitter prism 24 for the fourth time; here, the parallel light beam carrying the surface features of the sample to be measured 210 passes through the optical flat crystal 28 and is reflected by the polarization beam splitter prism 24.

[0044] The optical paths of the sample arm and the reference arm are of equal length. The light beam reflected by the sample arm and the light beam transmitted by the reflection arm are combined at the polarization beam splitter prism 24 to form elliptically polarized light or circularly polarized light, which is converted into vertically polarized light after passing through the second quarter-wave plate 23 and reflected to the imaging component 3 after passing through the first polarization beam splitter prism 22.

[0045] Please refer to Figure 4The object plane of the imaging assembly 3 is located on the optical flat crystal 28 or the concave reflector 26. After the object-side telecentric light beam passes through the front first lens 31 and the front second lens 32, it is reflected by the reflector 33 and transmitted through the aperture 34, the rear first lens 35 and the rear second lens 36, and then telecentrically imaged to the imaging camera 37. Here, the interference fringes formed by the combined beams of the sample arm and the reference arm are obtained through the imaging system 3 to obtain an interference fringe pattern. Among them, the focal length f1 of the front first lens 31 and the focal length f2 of the front second lens 32 satisfy the relationship: -0.58 < f1 / f2 < -0.69, the focal length f3 of the rear first lens 35 and the focal length f4 of the rear second lens 36 satisfy the relationship: -1.8 < f3 / f4 < -2.9, and the total focal length fg1 of the front lens group and the total focal length fg2 of the rear lens group satisfy the relationship: 0.99 < fg1 / fg2 < 1.01. The front first lens group 31, the front second lens group 32, the rear first lens group 35, and the rear second lens group 36 share the same optical axis, forming a lens sequence of "positive-negative-negative-positive". The front first lens group 31 and the rear second lens group 36 have a positive focal length, and the front second lens group 32 and the rear first lens group 35 have a negative focal length.

[0046] Imaging assembly 3 in this embodiment is a bi-telecentric imaging system, and basic lens data is shown in Table 1. The Surface Number column lists the surface numbers, starting with the object-side surface as surface 1 and increasing in number toward the image side. The Surface Type column lists the lens surface type. The Curvature Radius column shows the lens curvature radius, with a positive curvature radius indicating that the surface is curved toward the object space, and a negative curvature radius indicating that the surface is curved toward the object space. The Center Thickness column lists the distance between each lens surface and its image-side neighbor on the optical axis. The Refractive Index column lists the refractive index of the lens material. The Abbe Number column lists the Abbe number of the lens material.

[0047]

[0048]

[0049] Based on the basic lens data of the embodiment, for a 1060nm wavelength-corrected telecentric lens, the total optical length of the imaging system is 423.03mm. The focal lengths of the front first lens group 31 and the front second lens group 32 have a relationship of f1 / f2 = -0.63, and the focal lengths of the rear first lens group 35 and the rear second lens group 36 have a relationship of f3 / f4 = -2.32. The total focal lengths of the front and rear lens groups have a relationship of fg1 / fg2 = 0.993.

[0050] Figure 5 This is the wavefront phase difference diagram of the imaging component 3. The wavefront difference in the center field of view is 0.01λ, the wavefront difference at the half image height of 1.818mm is 0.018λ, the wavefront difference at the half image height of 3.636mm is 0.03λ, the wavefront difference at the half image height of 5.454mm is 0.021λ, and the wavefront difference at the half image height of 7.000mm is 0.048λ.

[0051] See also Figure 6 According to an interference detection device provided by the present invention, the interference detection method includes the following steps:

[0052] Step S1, detecting and calibrating the parallelism of the parallel light beam output by the beam shaping module 1 in front of the concave reflector 26;

[0053] Step S2, detecting and calibrating the parallelism of the output parallel light beam returned by the concave reflector 26 in front of the front first lens 31 of the imaging system 3;

[0054] Step S3, detecting the optical flat crystal 28 placed at the position of the sample 210 to be tested. The interference image obtained by the detection can be further calculated into a wavefront distribution or a surface shape distribution as correction information of the system;

[0055] In step S4 , the correction information is subtracted from the wavefront distribution or surface profile distribution of the interference pattern actually obtained from the sample 210 to be tested, thereby obtaining high-precision surface profile data of the sample 210 to be tested.

[0056] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A large-aperture anti-interference interference detection device based on a Michelson interferometer architecture, characterized by: It includes a beam shaping module (1), an interference component (2) and an imaging component (3); The interference assembly (2) includes a first quarter-wave plate (21), a first polarization beam splitter prism (22), a second quarter-wave plate (23), a second polarization beam splitter prism (24), a third quarter-wave plate (25), and a concave reflector (26) arranged in sequence on the main optical path; a fourth quarter-wave plate (27) and an optical flat crystal (28) are arranged in sequence on the sample arm optical path of the second polarization beam splitter prism (24), and a plane reflector (29) is arranged on the reference arm optical path of the second polarization beam splitter prism (24).

2. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 1, characterized in that: The imaging assembly (3) comprises a front group first lens (31), a front group second lens (32) and a reflector (33) located on the reflected light path of the first polarization beam splitting prism (22); an aperture (34), a rear group first lens (35), a rear group second lens (36) and an imaging camera (37) are provided on the reflected light path of the reflector (33).

3. A large-aperture anti-interference interference detection device based on a Michelson interferometer architecture according to claim 1 or 2, characterized in that: The beam shaping module (1) is composed of a polarized light source (11) containing a collimating lens and a shaping lens group (12).

4. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 3, characterized in that: The concave reflector (26) includes a spherical reflector, an aspherical reflector or a parabolic mirror.

5. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 3, characterized in that: The concave reflector (26) is a spherical reflector.

6. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 3, characterized in that: The concave reflector (26) can finely adjust the interval between its focus and the sample to be measured (210) along the optical axis, and the adjustment device includes but is not limited to a translation stage and a multi-axis adjustable mirror frame.

7. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 3, characterized in that: The optical flat crystal (28) is adjusted in displacement to match the optical path by a pointing and displacement adjustment device, and the inclination angle between its optical axis and the surface normal of the sample (210) to be measured is adjusted to be greater than 0 degrees and less than 0.5 degrees. The adjustment device includes but is not limited to a translation stage, a multi-axis mirror frame and a driving ceramic.

8. The large-aperture anti-interference interference detection device based on the Michelson interferometer architecture according to claim 3, characterized in that: The focal length f1 of the front group first lens (31) and the focal length f2 of the front group second lens (32) satisfy the relationship: -0.58<f1 / f2<-0.69, the focal length f3 of the rear group first lens (35) and the focal length f4 of the rear group second lens (36) satisfy the relationship: -1.8<f3 / f4<-2.9, and the total focal length fg1 of the front group lens and the total focal length fg2 of the rear group lens satisfy the relationship: 0.99<fg1 / fg2<1.01; the front group first lens (31), the front group second lens (32), the rear group first lens (35), and the rear group second lens (36) share the same optical axis, forming a "positive-negative-negative-positive" lens sequence, the front group first lens (31) and the rear group second lens (36) have positive focal lengths, and the front group second lens (32) and the rear group first lens (35) have negative focal lengths.

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