A grating surface defect qualitative and quantitative detection device and method

Abstract

The application discloses a grating surface defect qualitative and quantitative detection device and method, and relates to the field of precise instrument detection.The detection device comprises a laser, a transmission light splitting component, a first light receiver, a second light receiver and an analyzer; the first light receiver and the second light receiver are connected with the analyzer.The embodiment of the application utilizes the interference light reflected by the grating to obtain interference light by beam combining, then the interference light is split to obtain split light with the same polarization direction and different phases, the qualitative and quantitative detection of the grating surface defect is realized by the phase calculation of the split light with the same polarization direction and different phases, and the interference light is measured, so that the defect of low image detection precision caused by the reflection of ambient light by the grating surface is overcome, and the detection precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision instrument detection, in particular to a grating surface defect qualitative and quantitative detection device and method. BACKGROUND

[0002] As an important device in modern optics, gratings are widely used in spectral analysis, optical sensing and many other fields, and the quality requirements for gratings are becoming higher and higher. However, due to imperfections in the production and processing process, defects will occur on the surface of the grating, which will affect the performance of optical instruments with gratings as the core component, and even affect the normal work of the instrument. Therefore, more and more attention has been paid to the detection of grating surface defects.

[0003] Most of the grating surface defect detection devices on the market currently use optical microscopes to directly image, and then manually judge; or use the diffraction effect of gratings to image, and then analyze the diffraction pattern to identify defects. These not only have low detection efficiency and are easily affected by human error, but also due to the reflection phenomenon on the surface of the grating, the imaging quality of the image detection equipment is affected, which further affects the detection accuracy of the defects. At the same time, these methods are difficult to accurately qualitatively and quantitatively detect the defects of the grating. SUMMARY

[0004] The purpose of the present application is to provide a grating surface defect qualitative and quantitative detection device and method, which can realize the qualitative and quantitative detection of grating surface defects and improve the detection accuracy.

[0005] To achieve the above purpose, the present application provides the following scheme:

[0006] A grating surface defect qualitative and quantitative detection device, the detection device comprising: a laser, a transmission light splitting assembly, a first light receiver, a second light receiver and an analyzer; the first light receiver and the second light receiver are connected with the analyzer;

[0007] The laser is used to emit at least two interfering diffracted lights to the grating;

[0008] The transmission light splitting assembly is used to receive two diffracted lights reflected by the grating, and then split the light after the two diffracted lights are combined to obtain split light with the same polarization direction and different phases;

[0009] The first light receiver and the second light receiver are respectively used to receive two split lights with the same polarization direction and different phases, and send them to the analyzer;

[0010] The analyzer is used for phase unwrapping of two beams of split light with same polarization direction and different phases to obtain a phase unwrapping result; and the phase unwrapping result is used for representing a degree of surface defect of the grating.

[0011] Optionally, the detection device further comprises a grating image detection assembly connected with the analyzer.

[0012] The laser is further used for emitting 0-order diffraction light to the grating.

[0013] The grating image detection assembly is used for detecting 0-order diffraction light reflected by the grating to obtain a grating image.

[0014] The analyzer is further used for analyzing the grating image to determine a first-level defect of the grating surface.

[0015] Optionally, the grating image detection assembly comprises a first polarization beam splitter prism, a plano-concave lens and a first image acquisition device.

[0016] The first polarization beam splitter prism is arranged on a direct light path of the laser, and is located directly above the grating; the plano-concave lens is arranged directly above the first polarization beam splitter prism; and the first image acquisition device is arranged directly above the first polarization beam splitter prism.

[0017] The first image acquisition device is connected with the analyzer.

[0018] Optionally, the transmission beam splitting assembly comprises a first mirror, a second mirror, a second polarization beam splitter prism, a 1 / 4 glass sheet and a third polarization beam splitter prism.

[0019] The first mirror and the second mirror are symmetrically arranged on two sides of the first polarization beam splitter prism.

[0020] The second polarization beam splitter prism is located directly above the first image acquisition device, and two mutually perpendicular incident surfaces thereof are perpendicular to reflection light paths of the first mirror and the second mirror, respectively.

[0021] The 1 / 4 glass sheet is arranged on an exit light path of the second polarization beam splitter prism, and is parallel to an exit surface of the second polarization beam splitter prism.

[0022] The third polarization beam splitter prism is arranged on an exit light path of the 1 / 4 glass sheet, and an incident surface of the third polarization beam splitter prism is parallel to the 1 / 4 glass sheet.

[0023] The first light receiver and the second light receiver are arranged on two mutually perpendicular exit surfaces of the third polarization beam splitter prism respectively, and the light sensitive surface of the first light receiver and the light sensitive surface of the second light receiver are parallel to the two mutually perpendicular exit surfaces of the third polarization beam splitter prism respectively.

[0024] Optionally, the detection device further comprises a second image acquisition device, wherein the second image acquisition device is connected with the analyzer.

[0025] The second image acquisition device is arranged on another exit light path of the second polarization beam splitter prism.

[0026] The second image acquisition device is used for detecting interference light after two beams of diffracted light reflected by the grating are combined, and obtaining an interference fringe image.

[0027] The analyzer is further used for analyzing the interference fringe image, and determining secondary defects on the grating surface, wherein the size of the secondary defects is smaller than the size of the primary defects.

[0028] Optionally, the detection device further comprises an XY two-dimensional displacement platform.

[0029] The grating is arranged on the XY two-dimensional displacement platform.

[0030] Optionally, in the aspect of performing phase calculation on two beams of split light with the same polarization direction and different phases to obtain a phase calculation result, the analyzer is specifically used for:

[0031] performing phase calculation on two beams of split light with the same polarization direction and different phases to obtain a phase difference of the two beams of split light with the same polarization direction and different phases.

[0032] calculating an absolute value of a difference between the phase difference and a target phase difference as the phase calculation result, wherein the target phase difference is obtained by detecting and performing phase calculation on a grating without defects.

[0033] A grating surface defect qualitative and quantitative detection method, wherein the detection method applies the detection device, and the detection method comprises the following steps:

[0034] two beams of mutually interfering diffracted light are emitted to the grating;

[0035] two beams of mutually interfering diffracted light reflected by the grating are received, and the two beams of diffracted light are combined and then split to obtain two beams of split light with the same polarization direction and different phases;

[0036] phase calculation is performed on the two beams of split light with the same polarization direction and different phases to obtain a phase calculation result, wherein the phase calculation result is used for representing a degree of the grating surface defect.

[0037] Optionally, the detection method further comprises the following steps:

[0038] detecting 0th order diffraction light reflected by the grating to obtain a grating image;

[0039] analyzing the grating image to determine first-level defects on the grating surface.

[0040] Optionally, the detection method further comprises the following steps:

[0041] detecting interference light after the interference of two beams of diffraction light reflected by the grating to obtain an interference fringe image;

[0042] analyzing the interference fringe image to determine second-level defects on the grating surface; the size of the second-level defects is smaller than the size of the first-level defects.

[0043] According to the specific embodiments of the present application, the following technical effects are provided:

[0044] The embodiment of the present application provides a grating surface defect qualitative and quantitative detection device and device, the detection device comprises: laser, transmission optical splitting component, first light receiver, second light receiver and analyzer, the first light receiver and the second light receiver are connected with the analyzer. The embodiment of the present application utilizes the interference of the diffraction light reflected by the grating to obtain the interference light, then the interference light is split to obtain the split light with the same polarization direction and different phases, the qualitative and quantitative detection of the grating surface defects is realized by the phase calculation of the split light with the same polarization direction and different phases, and the embodiment of the present application measures the interference light, overcomes the low image detection precision caused by the reflection of the grating surface to the ambient light, and improves the detection precision. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0046] Figure 1 The structure diagram of the grating surface defect qualitative and quantitative detection device provided by the embodiment of the present application is shown in the figure.

[0047] Figure 2 The three-dimensional schematic diagram of the detection principle of the grating surface defect qualitative and quantitative detection device provided by the embodiment of the present application is shown in the figure.

[0048] Figure 3A two-dimensional front view of the detection principle of the grating surface defect qualitative and quantitative detection device provided by the embodiment of the present application is shown in the figure.

[0049] Figure 4 An interference fringe image defect schematic diagram provided by the embodiment of the present application is shown in the figure.

[0050] Figure 5 An ideal interference signal waveform schematic diagram provided by the embodiment of the present application is shown in the figure.

[0051] Figure 6 A smaller wave shape schematic diagram provided by the embodiment of the present application is shown in the figure.

[0052] Symbol explanation:

[0053] 1, laser; 201, first polarization beam splitter prism; 202, second polarization beam splitter prism; 203, third polarization beam splitter prism; 301, first mirror; 302, second mirror; 4, grating; 5, plano-concave lens; 601, first image acquisition device; 602, second image acquisition device; 6, double convex lens; 7, 1 / 4 glass; 801, first photoelectric receiver; 802, second photoelectric receiver; 9, XY two-dimensional displacement platform. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0055] The purpose of the present application is to provide a grating surface defect qualitative and quantitative detection device and method, which can realize qualitative and quantitative detection of grating surface defects and improve detection accuracy.

[0056] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0057] Embodiment 1

[0058] As Figure 1As shown, Embodiment 1 of the present invention provides a device for qualitative and quantitative detection of defects on a grating surface. The detection device includes: a laser 1, a transmission beam splitting component, a first optical receiver 801, a second optical receiver 802, and an analyzer. Both the first and second optical receivers 801 are connected to the analyzer. The laser 1 emits at least two interfering diffracted beams towards the grating 4. The transmission beam splitting component receives the two diffracted beams reflected from the grating, combines them, and then splits them to obtain beams with the same polarization direction but different phases. The first and second optical receivers 801 and 802 respectively receive the beams with the same polarization direction but different phases and send them to the analyzer. The analyzer performs phase calculation on the two beams with the same polarization direction but different phases to obtain a phase calculation result. The phase calculation result is used to characterize the degree of defects on the grating surface. The transmission beam splitting component includes: a first mirror, a second mirror, a second polarizing beam splitter prism, a quarter-glass slide, and a third polarizing beam splitter prism.

[0059] Furthermore, the detection device also includes a grating image detection component connected to the analyzer; at this time, the laser 1 is also used to emit 0th-order diffracted light towards the grating; the grating image detection component is used to detect the 0th-order diffracted light reflected by the grating to obtain a grating image; the analyzer is also used to analyze the grating image to determine first-order defects on the grating surface. The grating image detection component includes a first polarizing beam splitter 201, a plano-concave lens 5, and a first image acquisition device 601.

[0060] Furthermore, the detection device also includes a second image acquisition device 602, which is connected to the analyzer.

[0061] Furthermore, the detection device also includes an XY two-dimensional displacement platform; a grating is disposed on the XY two-dimensional displacement platform.

[0062] like Figures 1-3 As shown, the connection relationships and working principles of the above-mentioned devices are as follows:

[0063] The first polarization beam splitter 201 is arranged on the direct light path of the laser 1; the grating 4 is arranged on the XY two-dimensional displacement platform 9 surface directly below the first polarization beam splitter 201, and the surface of the grating 4 is parallel to the light exit surface of the first polarization beam splitter 201; the plano-concave lens 5 and the first image acquisition device 601 are sequentially arranged above the first polarization beam splitter 201, and the plane of the plano-concave lens 5 and the acquisition surface of the first image acquisition device 601 are parallel to the light exit surface of the first polarization beam splitter 201; the first mirror 601 and the second mirror 602 are symmetrically arranged on the left and right sides of the first polarization beam splitter 201; the second polarization beam splitter 202 is arranged above the first polarization beam splitter 201, and the two mutually perpendicular incident surfaces are perpendicular to the reflected light paths of the first mirror 301 and the second mirror 302; the 1 / 4 glass 7 is arranged on the exit light path of the second polarization beam splitter 202, and is parallel to the light exit surface of the second polarization beam splitter 202; the incident surface of the third polarization beam splitter 203 is parallel to the exit surface of the 1 / 4 glass 7; the light sensitive surfaces of the first photoelectric receiver 801 and the second photoelectric receiver 802 are parallel to the two mutually perpendicular exit surfaces of the third polarization beam splitter 203.

[0064] The laser 1 is a single-frequency laser, and the beam polarization state is linearly polarized light.

[0065] As shown in Figure 2 and Figure 3 , the linearly polarized light emitted by the laser 1 is perpendicular to the grating 4 after passing through the first polarization beam splitter 201, generating three beams of diffracted light of 0th order, +1st order and -1st order.

[0066] The 0th order diffracted light returns to the original path, passes through the first polarization beam splitter 201, is perpendicular to the incident plane-concave lens 5, is diverged by the plane-concave lens 5, and is incident on the first image acquisition device 601. According to the grating image collected by the first image acquisition device 601, some obvious defects (first-level defects) on the surface of the grating are identified by an image detection method, such as cracks, depressions, protrusions, obvious scratches, etc.

[0067] The +1st order diffracted light (right side) is reflected by the first mirror 301 and then is perpendicular to the incident second polarization beam splitter 202, and the -1st order diffracted light (left side) is reflected by the second mirror 302 and then is perpendicular to the incident second polarization beam splitter 202. The +1st order and -1st order diffracted light incident on the second polarization beam splitter 202 is combined at the beam splitting surface of the second polarization beam splitter 202, and then is divided into two beams of exit light with perpendicular polarization directions. The exit light of the first exit surface of the second polarization beam splitter 202 is perpendicular to the second image acquisition device 602, and the exit light of the second exit surface of the second polarization beam splitter 202 is perpendicular to the 1 / 4 glass 7.

[0068] Wherein, the polarization direction of the combined beam incident light entering the second image acquisition device 602 is the same, interference occurs, and interference fringes are generated and received by the second image acquisition device 602, as shown in Figure 4 As described above, the defects will affect the interference fringe image, and through detection of the interference fringe image, some small defects (secondary defects) that cannot be captured by the first image acquisition device can be identified, the type of defect is distinguished, the size of the defect is detected, and the position of the defect is located in combination with the real-time feedback position of the XY two-dimensional displacement platform.

[0069] The combined beam linearly polarized light vertically entering the 1 / 4 wave plate 7 becomes circularly polarized light after passing through the 1 / 4 wave plate 7, and the circularly polarized light is divided into two beams after passing through the third polarizing beam splitter 203, and the two beams enter the first photoelectric receiver 801 and the second photoelectric receiver 802 respectively. The polarization directions of the combined beams of the first photoelectric receiver 801 and the second photoelectric receiver 802 are the same, interference occurs, and therefore two chord wave signals with a phase difference of 90° are obtained at the two photoelectric receivers. Through signal phase detection and calculation of the two chord wave signals with a phase difference of 90°, defects that cannot be identified by the image acquisition device can be detected, such as nanometer-level grating lines being damaged and the like.

[0070] The XY two-dimensional displacement platform 9 is driven to move at a uniform speed together with the grating 4, and when the grating lines are ideal and have no defects, as shown in Figure 5 As shown, the two waveforms detected by the photoelectric receiver are smooth, and the phase difference of the chord wave signals is 90 degrees. Through signal phase calculation, a monotonically increasing and decreasing periodic function can be obtained.

[0071] When the grating pitch of a part of the grating 4 is damaged, as shown in Figure 6 As shown, the waveform of the interference signal will change greatly, and when the waveform changes are small, only the phase calculation effect will be affected, but the signal phase calculation will not be affected. When the waveform changes are large, the phase of the interval cannot be calculated.

[0072] The above three defects will cause the calculated signal phase to be different from the signal phase calculated under ideal conditions. Through identification and calculation of the difference, the qualitative and quantitative detection of the defects can be realized, and the position of the defects can be located in combination with the real-time feedback position of the XY two-dimensional displacement platform.

[0073] Embodiment 2

[0074] The embodiment 2 of the present application provides a grating surface defect qualitative and quantitative detection method, and the detection method applies the detection device described above. The detection method comprises the following steps:

[0075] Two mutually interfering diffracted lights are emitted to the grating.

[0076] The two beams of diffracted light reflected by the grating interfere with each other, and after the two beams of diffracted light are combined and then split, two beams of split light with the same polarization direction and different phases are obtained.

[0077] The two beams of split light with the same polarization direction and different phases are phase-resolved to obtain a phase-resolved result; the phase-resolved result is used to represent the degree of surface defects of the grating.

[0078] Further, the detection method further includes the following steps:

[0079] The 0-order diffracted light reflected by the grating is detected to obtain a grating image.

[0080] The grating image is analyzed to determine the first-level defects of the grating surface.

[0081] Further, the detection method further includes the following steps:

[0082] The interference light after the two beams of diffracted light reflected by the grating are combined is detected to obtain an interference fringe image.

[0083] The interference fringe image is analyzed to determine the second-level defects of the grating surface; the size of the second-level defects is smaller than the size of the first-level defects.

[0084] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0085] The principles and implementation manners of the present disclosure are described by using specific examples in the present disclosure, and the above descriptions of the embodiments are only used to help understand the method of the present disclosure and its core idea; meanwhile, for those skilled in the art, according to the idea of the present disclosure, the specific implementation manners and application ranges can be changed. In conclusion, the content of the present disclosure should not be understood as a limitation of the present disclosure.

Claims

1. A device for qualitative and quantitative detection of defects on a grating surface, characterized in that, The detection device includes: a laser, a transmission beam splitter, a first optical receiver, a second optical receiver, and an analyzer; both the first optical receiver and the second optical receiver are connected to the analyzer. The laser is used to emit at least two interfering diffracted beams toward the grating; The transmission beam splitting component is used to receive two diffracted beams reflected by the grating, combine the two diffracted beams, and then split them to obtain two beams of split light with the same polarization direction but different phases. The first optical receiver and the second optical receiver are respectively used to receive two beams of split light with the same polarization direction but different phases, and send them to the analyzer; The analyzer is used to perform phase calculation on two beams of light with the same polarization direction but different phases to obtain the phase calculation result; the phase calculation result is used to characterize the degree of defects on the grating surface.

2. The grating surface defect qualitative and quantitative detection device according to claim 1, characterized in that, The detection device further includes: a grating image detection component, which is connected to the analyzer; The laser is also used to emit zero-order diffraction light toward the grating; The grating image detection component is used to detect the 0th order diffracted light reflected by the grating to obtain the grating image; The analyzer is also used to analyze the grating image to determine first-order defects on the grating surface.

3. The grating surface defect qualitative and quantitative detection device according to claim 2, characterized in that, The grating image detection component includes a first polarizing beam splitter, a plano-concave lens, and a first image acquisition device; The first polarizing beam splitter is disposed on the direct optical path of the laser, and the first polarizing beam splitter is located directly above the grating. The plano-concave lens is disposed directly above the first polarizing beam splitter, and the first image acquisition device is disposed directly above the first polarizing beam splitter. The first image acquisition device is connected to the analyzer.

4. The grating surface defect qualitative and quantitative detection device according to claim 3, characterized in that, The transmission beam splitting assembly includes: a first reflector, a second reflector, a second polarizing beam splitter, a quarter glass slide, and a third polarizing beam splitter; The first and second reflectors are symmetrically arranged on both sides of the first polarizing beam splitter; The second polarizing beam splitter is located directly above the first image acquisition device, and its two mutually perpendicular incident surfaces are perpendicular to the reflected light paths of the first and second reflecting mirrors, respectively. The 1 / 4 glass slide is disposed in one of the outgoing light paths of the second polarizing beam splitter and is parallel to the outgoing surface of the second polarizing beam splitter; The third polarizing beam splitter is disposed in the outgoing light path of the quarter glass slide, and the incident surface of the third polarizing beam splitter is parallel to the quarter glass slide. The first optical receiver and the second optical receiver are respectively disposed on two mutually perpendicular exit surfaces of the third polarizing beam splitter; and the photosensitive surfaces of the first optical receiver and the second optical receiver are respectively parallel to the two mutually perpendicular exit surfaces of the third polarizing beam splitter.

5. The grating surface defect qualitative and quantitative detection device according to claim 4, characterized in that, The detection device further includes: a second image acquisition device, which is connected to the analyzer; The second image acquisition device is configured on another outgoing light path of the second polarizing beam splitter; The second image acquisition device is used to detect the interference light after the two diffracted beams reflected from the grating are combined, and to obtain an interference fringe image; The analyzer is also used to analyze the interference fringe image to determine secondary defects on the grating surface; the size of the secondary defects is smaller than the size of the primary defects.

6. The grating surface defect qualitative and quantitative detection device according to claim 1, characterized in that, The detection device also includes an XY two-dimensional displacement platform; The grating is set on the XY two-dimensional displacement platform.

7. The grating surface defect qualitative and quantitative detection device according to claim 1, characterized in that, In terms of obtaining phase calculation results from two beams of split light with the same polarization direction but different phases, the analyzer is specifically used for: Phase calculation is performed on two beams of light with the same polarization direction but different phases to obtain the phase difference between the two beams of light with the same polarization direction but different phases. The absolute value of the difference between the phase difference and the target phase difference is calculated as the phase solution result; The target phase difference is obtained by detecting and calculating the phase of a defect-free grating.

8. A method for qualitative and quantitative detection of defects on a grating surface, characterized in that, The detection method uses the detection apparatus according to any one of claims 1-7, and the detection method includes the following steps: Two interfering diffracted beams are emitted toward the grating; The two diffracted beams reflected from the grating interfere with each other, and after combining the two diffracted beams, they are split to obtain two beams with the same polarization direction but different phases. Phase calculation is performed on two beams of light with the same polarization direction but different phases to obtain the phase calculation result; the phase calculation result is used to characterize the degree of defects on the grating surface.

9. The method for qualitative and quantitative detection of grating surface defects according to claim 8, characterized in that, The detection method further includes the following steps: The 0th order diffracted light reflected from the grating is detected to obtain the grating image; The grating image is analyzed to determine the first-order defects on the grating surface.

10. The method for qualitative and quantitative detection of grating surface defects according to claim 9, characterized in that, The detection method further includes the following steps: The interference light after the two diffracted beams reflected from the grating are combined is detected to obtain an interference fringe image; The interference fringe image is analyzed to determine secondary defects on the grating surface; the size of the secondary defects is smaller than the size of the primary defects.

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