CN109916909B - Method and device for detecting surface morphology and subsurface defect information of optical element - Google Patents
Method and device for detecting surface morphology and subsurface defect information of optical element Download PDFInfo
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Abstract
The invention relates to a method and a device for detecting surface morphology and subsurface defect information of an optical element. The method comprises the steps of measuring distance by using wavelength information, emitting a beam of polychromatic light (white) with a wide spectrum by a light source, generating spectral dispersion by a dispersion lens to form monochromatic light with different wavelengths, wherein the focus of each wavelength corresponds to a distance value; the measuring light is emitted to the surface of an object and is reflected back, only monochromatic light meeting confocal conditions can be sensed by the spectrometer through the small hole, and the distance value is obtained through conversion by calculating the wavelength of a sensed focus. The two spectrometers are used for respectively receiving the light wave information of the surface and the internal defect of the element to be measured, so that the surface information of the optical element, the position and the depth information of the internal defect and the like can be obtained simultaneously.
Description
Technical Field
The invention relates to a method and a device for detecting surface morphology and subsurface defect information of an optical element.
Background
With the increasing and continuous development of energy of high-power solid-state laser systems, the requirements on the quality of optical elements are higher and higher. A great deal of research on the damage mechanism of the optical element at home and abroad shows that the subsurface defect generated in the processing processes of grinding, polishing and the like of the optical element is one of the important factors causing the reduction of the damage resistance of the optical element. Therefore, how to effectively detect and evaluate the subsurface defects of the optical element with different depth sizes and morphological characteristics so as to guide the element processing, and effectively control the subsurface defects generated in each process step to become the cutting requirement for manufacturing the high-threshold laser damage resistant optical element. At present, two types of methods are mainly adopted to detect the subsurface defect of the element, wherein one type of method is a destructive method for directly exposing and observing the subsurface defect, namely destructive detection, such as a pit hitting method, an acid etching method, magnetorheological wedge angle processing and the like; the other is non-destructive, i.e., non-destructive, detection, such as scattering methods, Total Internal Reflection Microscopy (TIRM) techniques, confocal microscopy, etc. Conventional prior art techniques are not well-suited for the detection of sub-surface defects of optical components, such as the location of defects within the component, depth information, and the like. Therefore, how to effectively detect the depth information of the subsurface defect becomes an important direction for optical detection.
Disclosure of Invention
The invention provides a method and a device for detecting surface morphology and subsurface defect information of an optical element, which measure distance by using wavelength information, emit a beam of polychromatic light (white) with a wide spectrum from a light source, and generate spectral dispersion through a dispersion lens to form monochromatic light with different wavelengths. The focus of each wavelength corresponds to a distance value; the measuring light is emitted to the surface of an object and reflected back, only monochromatic light meeting confocal conditions can be sensed by the spectrograph through the small hole, the distance value is obtained through calculating the wavelength of a sensed focus and converting, and the two spectrometers are used for respectively receiving the light wave information of the surface of the element to be measured and the internal defect, so that the surface information of the optical element, the position of the internal defect, the depth information and the like can be obtained simultaneously.
In order to solve the problems in the prior art, the technical scheme of the invention is as follows: the method for detecting the surface morphology and subsurface defect information of the optical element is characterized by comprising the following steps: the detection method comprises the following steps:
the method comprises the following steps: emitting a beam of polychromatic light with a wide spectrum from a light source, passing through the small hole S, and converting a common light source into linearly polarized light with a vibration direction vertical to an XOY plane after passing through the polaroid, and irradiating the linearly polarized light on the dispersion lens group;
step two: the light is converged by the dispersion lens and then irradiates on an object to be measured, the dispersion lens converges the monochromatic light with the wavelength on the surface of the object, the monochromatic light with the wavelength is converged on the subsurface defect in the object, the light is scattered by the surface and subsurface defects, and the backscattered light passes through the dispersion lens again;
step three: after being reflected by a spectroscope at an angle of 45 degrees, scattered light collected by the dispersion lens horizontally enters a diaphragm, the diaphragm is a rectangular space filter with a large ratio, the length direction of the rectangular space filter is vertical to an XOY plane, and the surface scattered light has larger polarization degree after passing through the diaphragm;
step four: the scattered light with the wavelength converged on the surface of the object passes through the polarization beam splitter prism and then is converged on the small hole S' to reach the first spectrometer;
step five: the polarization state of the scattered light with the wavelength of the light converged on the subsurface defect is changed, one part of the light passes through the polarization beam splitter prism and is converged on the small hole S ' through transmission to reach the first spectrometer, and the other part of the light passes through the polarization beam splitter prism and is converged on the small hole S ' ' to reach the second spectrometer;
step six: the spectrum of the spectrometer I has a peak value at the position of the sum, and the surface scattering signal is far stronger than the sub-surface defect scattering signal, so that the wavelength of the surface convergent light is obtained, and the position information of the surface is determined according to the relation between the wavelength and the convergence point;
step seven: the spectrum of the spectrometer II is converged to the wavelength of the subsurface defect light to form a peak value, and the position of the subsurface defect is obtained according to the relation between the wavelength and the convergence point;
step eight: obtaining depth information of the subsurface defect according to the surface position information and the subsurface defect position information;
step nine: when a plurality of defects exist at the same detection position, a plurality of peak values appear on the spectrum of the spectrometer II, and the sub-surface defect distribution at the detection position is determined;
step ten: and (3) translating the detection system on the surface of the optical element in a two-dimensional manner to obtain surface position information and sub-surface defect information on different positions for three-dimensional reconstruction, so as to obtain the surface appearance and the sub-surface defect information of the optical element.
The polychromatic light in the first step is white light.
The detection device is used for detecting the surface appearance and the subsurface defect information of the optical element, and comprises a white light point light source, a polaroid, a spectroscope, a dispersive lens group, a diaphragm, a polarization beam splitter prism, a first spectrometer, a second spectrometer and a computer;
the white light point light source, the polaroid, the spectroscope and the dispersive lens group are sequentially arranged on an optical axis, the beam splitter prism is arranged on one side of the spectroscope, a narrow rectangular diaphragm which is centered on an incident surface and positioned on a surface normal is arranged in front of the beam splitter prism, the first spectrometer and the second spectrometer are respectively arranged on two vertical light paths of the beam splitter prism, and the first spectrometer and the second spectrometer are connected with the computer.
The angle of the spectroscope is set to be 45 degrees.
Compared with the prior art, the invention has the following advantages:
1. the invention can simultaneously obtain the surface information of the element to be measured and the depth information of the subsurface defect, has high measurement efficiency and can realize large-view and high-speed scanning;
2. the invention can detect all optical materials (flexible, transparent and mirror surface), and has high measurement capability;
3. the invention has high measurement precision.
Drawings
FIG. 1 is a schematic view of a detection apparatus according to the present invention;
FIG. 2 is a left side view of the diaphragm;
in the figure: 1. a white light point source; 2. a polarizing plate; 3. a beam splitter; 4. a dispersive lens group; 5. an object to be measured; 6. a diaphragm; 7. a beam splitter prism; 8. a first spectrometer; 9. a second spectrometer; 10. and (4) a computer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The method for detecting the surface topography and the subsurface defect depth information of the optical element comprises the following steps:
the method comprises the following steps: emitting a beam of polychromatic light with a wide spectrum from a light source, passing through the small hole S, and after passing through the polaroid 2, converting the common light source into linearly polarized light with a vibration direction vertical to the XOY plane, and irradiating the linearly polarized light on the dispersion lens group;
step two: the light rays are subjected to spectral dispersion through the dispersion lens, so that the white light is dispersed into monochromatic light with different wavelengths, and the focus of each wavelength corresponds to a fixed distance value; then the light is converged and then irradiates on an object to be measured, the dispersion lens converges the monochromatic light with the wavelength on the surface of the object, the monochromatic light with the wavelength is converged on the subsurface defect, the light is scattered through the surface and the subsurface defect, and the backscattered light passes through the dispersion lens again.
Step three: since light rays in each direction in space need to be converged and then irradiated on the surface of an object after spectral dispersion occurs, and light rays in other directions are converged and polarization in the direction is generated on the surface of the object, when scattered light enters a polarization splitting Prism (PBS) 7, the incident light is neither S light nor P light, but has components in both directions, and for an incident angle, the vibration direction of the synthesized light is changed due to the difference of reflectance of the S light and the P light. For this purpose, a narrow rectangular diaphragm 6 centered on the incident surface and on the surface normal needs to be added in front of the PBS; scattered light collected by the dispersive lens is reflected by a spectroscope at an angle of 45 degrees and horizontally enters a diaphragm 6, the diaphragm 6 is a rectangular space filter with a large ratio, the length direction of the rectangular space filter is vertical to an XOY plane, and surface scattered light has larger polarization degree after passing through the diaphragm;
step four: the light irradiated on the surface of the object is perfectly focused on the surface of the object, so that the scattered light on the surface of the object keeps the original polarization state, passes through the polarization splitting prism and then just converges on the small hole S' to reach the first spectrometer;
step five: the polarization state of the scattered light with the wavelength of the light converged on the subsurface defect is changed, one part of the scattered light passes through the polarization beam splitter prism and is converged on the small hole S ' through transmission to reach the first spectrometer, and the other part of the scattered light passes through the polarization beam splitter prism and is converged on the small hole S ' ' to reach the second spectrometer;
step six: the spectrum of the first spectrometer has a peak value at the position of the sum, because the surface scattering signal is far stronger than the sub-surface defect scattering signal, the wavelength of the surface converging light can be obtained, and the position information of the surface is determined according to the relation between the wavelength and the convergence point, but the peak value is far smaller than the peak value, so that the surface converging light is not easy to obtain;
step seven: the spectrum of the spectrometer II has a peak value only at the wavelength of the light converged to the subsurface defect, and the position of the subsurface defect can be obtained according to the relation between the wavelength and the convergence point;
step eight: obtaining the depth information of the subsurface defect according to the surface position information and the subsurface defect position information;
step nine: when a plurality of defects exist at the same detection position, a plurality of peaks appear on the spectrum of the second spectrometer, and the sub-surface defect distribution at the detection position can be determined.
Step ten: the detection system is translated on the surface of the optical element in two dimensions, surface position information and sub-surface defect information at different positions are obtained and reconstructed in three dimensions, and the surface appearance and the sub-surface defect information of the optical element can be obtained.
The polychromatic light is white light.
The invention can also detect some special objects, if the defect in the object is not a point but a small block with a certain area, for example, the object has a small bubble in the object, and the surface contour information of the bubble can also be measured by using the method. After passing through the polaroid, the polychromatic light is changed into linearly polarized light with a certain vibration direction, the linearly polarized light irradiates on the beam splitter prism, then the light is converged, the monochromatic light just irradiates on the surface of an object, and the monochromatic light irradiates on the upper surface and the lower surface of the bubble respectively; after the light is reflected back and passes through the polarization beam splitting prism, the light is identified by the first spectrometer 8 to obtain object surface information; and the depth of the internal defect of the object can be obtained according to the refractive index after the distance value is identified by the second spectrometer 9 and corresponds to different distance values. Several wave crests with different heights can appear on the measured spectrum, a gray scale map can be drawn according to different wave crests and a corresponding range and the refractive index, and then the range of the defect is judged according to different brightness conditions on the gray scale map. The bright place represents that the scattered light is strong, the nonuniformity of the internal defect is strong, the dark place represents that the light ratio is weak, the nonuniformity is weak, and the position of the defect can be judged according to the nonuniformity.
The detection device (see fig. 1 and 2) for detecting the information of the surface topography and the depth of the subsurface defect of the optical element comprises a white light point light source 1, a polaroid 2 spectroscope 3, a dispersive lens group 4, a diaphragm 6, a polarization beam splitter prism 7, a first spectrometer 8, a second spectrometer 9 and a computer 10;
the white light point light source 1, the polaroid 2, the spectroscope 3 and the dispersion lens group 4 are sequentially arranged on an optical axis, the beam splitter prism 7 is arranged on one side of the spectroscope 3, the narrow rectangular diaphragm 6 which is centered on an incident surface and positioned on a surface normal is arranged in front of the beam splitter prism 7, the first spectrometer 8 and the second spectrometer 9 are respectively arranged on two vertical light paths of the beam splitter prism 7, and the first spectrometer 8 and the second spectrometer 9 are finally connected with the computer 10.
The angle of the beam splitter 3 is 45 °.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.
Claims (4)
1. The method for detecting the surface morphology and subsurface defect information of the optical element is characterized by comprising the following steps: the detection method comprises the following steps:
the method comprises the following steps: emitting a beam of polychromatic light with a wide spectrum from a light source, passing through the small hole S, and converting a common light source into linearly polarized light with a vibration direction vertical to an XOY plane after passing through the polaroid, and irradiating the linearly polarized light on the dispersion lens group;
step two: the light is converged by the dispersion lens and then irradiates on an object to be measured, the dispersion lens converges the monochromatic light with the wavelength on the surface of the object, the monochromatic light with the wavelength is converged on the subsurface defect in the object, the light is scattered by the surface and subsurface defects, and the backscattered light passes through the dispersion lens again;
step three: after being reflected by a spectroscope at an angle of 45 degrees, scattered light collected by the dispersion lens horizontally enters a diaphragm, the diaphragm is a rectangular space filter with a large ratio, the length direction of the rectangular space filter is vertical to an XOY plane, and the surface scattered light has larger polarization degree after passing through the diaphragm;
step four: the scattered light with the wavelength converged on the surface of the object passes through the polarization beam splitter prism and then is converged on the small hole S' to reach the first spectrometer;
step five: the polarization state of the scattered light with the wavelength of the light converged on the subsurface defect is changed, one part of the light passes through the polarization beam splitter prism and is converged on the small hole S ' through transmission to reach the first spectrometer, and the other part of the light passes through the polarization beam splitter prism and is converged on the small hole S ' ' to reach the second spectrometer;
step six: the spectrum of the spectrometer I has a peak value at the position of the sum, and the surface scattering signal is far stronger than the sub-surface defect scattering signal, so that the wavelength of the surface convergent light is obtained, and the position information of the surface is determined according to the relation between the wavelength and the convergence point;
step seven: the spectrum of the spectrometer II is converged to the wavelength of the subsurface defect light to form a peak value, and the position of the subsurface defect is obtained according to the relation between the wavelength and the convergence point;
step eight: obtaining depth information of the subsurface defect according to the surface position information and the subsurface defect position information;
step nine: when a plurality of defects exist at the same detection position, a plurality of peak values appear on the spectrum of the spectrometer II, and the sub-surface defect distribution at the detection position is determined;
step ten: and (3) translating the detection system on the surface of the optical element in a two-dimensional manner to obtain surface position information and sub-surface defect information on different positions for three-dimensional reconstruction, so as to obtain the surface appearance and the sub-surface defect information of the optical element.
2. The method as claimed in claim 1, wherein the method further comprises the steps of: the polychromatic light in the first step is white light.
3. A detection apparatus for implementing the method for detecting surface topography and subsurface defect information of an optical element according to claim 1, wherein: the device comprises a white light point light source (1), a polaroid (2), a spectroscope (3), a dispersion lens group (4), a diaphragm (6), a polarization splitting prism (7), a first spectrometer (8), a second spectrometer (9) and a computer (10);
white light point light source (1), polaroid (2), spectroscope (3) and dispersion lens group (4) set gradually on the optical axis, spectral prism (7) set up in one side of spectroscope (3), the preceding of spectral prism (7) is provided with and uses the incident surface as the center, narrow rectangle diaphragm (6) that are located on the surface normal, spectrum appearance (8) and spectrum appearance two (9) set up respectively in two looks perpendicular light paths of spectral prism (7), spectrum appearance (8) are connected with computer (10) with spectrum appearance two (9).
4. The detection device according to claim 3, wherein: the angle of the spectroscope (3) is set to be 45 degrees.
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| CN110426397B (en) * | 2019-08-14 | 2022-03-25 | 深圳市麓邦技术有限公司 | Optical detection system, device and method |
| CN111220625B (en) * | 2020-01-18 | 2023-04-07 | 哈尔滨工业大学 | Surface and sub-surface integrated confocal microscopic measurement device and method |
| CN111239154A (en) * | 2020-01-18 | 2020-06-05 | 哈尔滨工业大学 | Transverse differential dark field confocal microscopic measurement device and method thereof |
| CN111239153B (en) * | 2020-01-18 | 2023-09-15 | 哈尔滨工业大学 | Axial differential dark field confocal microscopic measuring device and method thereof |
| CN111257225B (en) * | 2020-01-18 | 2023-08-15 | 南京恒锐精密仪器有限公司 | Transverse differential dark field confocal microscopic measuring device and method thereof |
| CN111220624A (en) * | 2020-01-18 | 2020-06-02 | 哈尔滨工业大学 | Surface and sub-surface integrated confocal microscopic measurement device and method |
| CN111239155B (en) * | 2020-01-18 | 2023-06-23 | 哈尔滨工业大学 | Axial differential dark field confocal microscopic measuring device and method thereof |
| CN111879239B (en) * | 2020-06-11 | 2022-09-02 | 东莞市神州视觉科技有限公司 | Spectrum confocal measuring device and measuring method |
| CN113281343B (en) * | 2021-05-31 | 2022-12-27 | 中国科学院西安光学精密机械研究所 | System and method for detecting defects of multilayer transparent material |
| US11835472B2 (en) | 2021-08-05 | 2023-12-05 | Zhejiang University | Device and method for detecting subsurface defect of optical component |
| CN113607750B (en) * | 2021-08-05 | 2022-06-14 | 浙江大学 | Device and method for detecting subsurface defect of optical element |
| CN113533351B (en) * | 2021-08-20 | 2023-12-22 | 合肥御微半导体技术有限公司 | Panel defect detection device and detection method |
| CN114279342A (en) * | 2021-12-29 | 2022-04-05 | 青岛国科虹成光电技术有限公司 | Chromatic dispersion compensation nature chromatogram confocal measuring apparatu |
| CN114324369B (en) * | 2022-03-11 | 2022-06-07 | 北京新研创能科技有限公司 | System and method for detecting scratches on surface of bipolar plate |
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| JP3379805B2 (en) * | 1993-05-13 | 2003-02-24 | オリンパス光学工業株式会社 | Surface defect inspection equipment |
| JP2002333407A (en) * | 2001-05-09 | 2002-11-22 | Horiba Ltd | Defect inspection device of plane display device |
| US8619237B2 (en) * | 2009-12-04 | 2013-12-31 | The Trustees Of Columbia University In The City Of New York | Laser-scanning intersecting plane tomography such as for high speed volumetric optical imaging |
| CN102519976A (en) * | 2011-12-26 | 2012-06-27 | 上海大学 | Digital holographic detection device for subsurface defect of optical element |
| CN103105400B (en) * | 2013-01-29 | 2015-08-26 | 合肥知常光电科技有限公司 | The detection sorting technique of optical elements of large caliber surface imperfection |
| CN106802129A (en) * | 2016-12-30 | 2017-06-06 | 中国科学院光电研究院 | A kind of high resolution and self calibration Spectral Confocal displacement measurement system |
| CN109668838B (en) * | 2018-11-13 | 2020-07-03 | 浙江大学 | Device and method capable of simultaneously detecting surface and subsurface defects of optical element |
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