CN115128763A - Differential automatic focusing measuring method - Google Patents
Differential automatic focusing measuring method Download PDFInfo
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- CN115128763A CN115128763A CN202210821339.2A CN202210821339A CN115128763A CN 115128763 A CN115128763 A CN 115128763A CN 202210821339 A CN202210821339 A CN 202210821339A CN 115128763 A CN115128763 A CN 115128763A
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000003287 optical effect Effects 0.000 claims description 18
- 238000005286 illumination Methods 0.000 claims description 5
- 238000000691 measurement method Methods 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 description 16
- 238000003384 imaging method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 238000005498 polishing Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/285—Systems for automatic generation of focusing signals including two or more different focus detection devices, e.g. both an active and a passive focus detecting device
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/282—Autofocusing of zoom lenses
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B13/00—Viewfinders; Focusing aids for cameras; Means for focusing for cameras; Autofocus systems for cameras
- G03B13/32—Means for focusing
- G03B13/34—Power focusing
- G03B13/36—Autofocus systems
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- Optics & Photonics (AREA)
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- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention provides a differential automatic focusing measuring method, which comprises the steps that a light source emits focusing light, the light generated by the light source is straightened through a straightening lens group to generate parallel light, the parallel light is reflected through a first spectroscope and is converged on the surface of a sample through an objective lens, the focusing light is reflected on the surface of the sample, the focusing light is converted into the parallel light through the objective lens, the parallel light passes through the spectroscope and starts to be converged through the objective lens, the converging light generated by the lens is divided to a first photosensitive device and a second photosensitive device through a second spectroscope, the defocusing amount of the sample is judged through the light intensity difference between the first photosensitive device and the second photosensitive device, and focusing is realized if the light intensity difference is 0. According to the method, the defocusing amount of the measured object can be calculated by acquiring the image once, so that rapid focusing is realized, and the focusing accuracy is improved.
Description
Technical Field
The present invention relates to the field of camera focusing, and more particularly, to a differential auto-focusing measurement method.
Background
At present, the existing microscopic focusing method mostly starts from image blurring, and determines whether a camera is focused or not by judging the edge blurring degree of an image or the edge size of an image spot. The method has great limitation in the scene requiring high-precision measurement, wherein the precision of the measurement system can be reduced due to the fact that the fuzzy degree is not clearly defined, and the size of the facula edge can be influenced by artificial subjective threshold segmentation.
Disclosure of Invention
The invention mainly aims to overcome the defects in the prior art and provide a differential automatic focusing measuring method, which utilizes the conjugate relation of the camera imaging before focusing and after focusing to find the functional relation between the light intensity difference and the defocusing amount of a sample in the defocusing state, can calculate the defocusing amount of a measured object by acquiring an image once, realizes quick focusing and improves the focusing accuracy.
The invention adopts the following technical scheme:
a differential autofocus measurement method, comprising: a differential auto-focusing measuring system specifically comprises: the method comprises the following steps: the device comprises a light source, a collimating lens group, a first spectroscope, an objective lens, a tube lens, a second spectroscope, a first optical sensor and a second optical sensor;
the light source is used for emitting illumination light, and the collimating lens group is used for emitting horizontal parallel light which is used for emitting transaction illumination light; the first spectroscope is used for reflecting incident light in the horizontal parallel light and measuring light transmission; the objective lens is used for measuring an object; the tube lens is used for converging light rays; the second spectroscope is used for dividing light into two light paths to enter the first optical sensor and the second optical sensor; the first optical sensor is positioned in front of the light convergence point d 1 Where the second optical sensor is positioned behind the light convergence point d 2 Treating;
the light source emits focusing light, the focusing light passes through the straightening lens group to be straightened to generate parallel light, the parallel light is reflected by the first spectroscope and is converged on the surface of a sample through the objective lens, the focusing light is reflected by the surface of the sample, the focusing light is converted into the parallel light through the objective lens, the parallel light passes through the spectroscope and starts to be converged through the objective lens, the converging light generated by the tube lens is divided into the first photosensitive device and the second photosensitive device through the second spectroscope, the defocusing amount of the sample is judged through the light intensity difference between the first photosensitive device and the second photosensitive device, and if the light intensity difference is 0, focusing is achieved.
Specifically, the light source is a collimated light source or a point light source.
Specifically, the positions of the objective lens and the second spectroscope are interchanged, and after the positions are interchanged, an eyepiece needs to be placed in front of both the objective lens and the second spectroscope.
Specifically, the first photosensitive device is a pre-focus camera, and the second photosensitive device is a post-focus camera.
As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:
(1) the invention provides a differential automatic focusing measuring method, which utilizes the conjugate relation of camera imaging before and after focusing to find the functional relation between the light intensity difference and the defocusing amount of a sample in the defocusing state; the method can calculate the defocusing amount of the measured object by acquiring the image once, and realizes quick focusing.
(2) The method calculates the average defocusing amount by shooting a plurality of point light sources, improves the focusing accuracy, and also improves the universality.
Drawings
Fig. 1 is an architecture diagram of a differential auto-focus measurement system according to an embodiment of the present invention.
FIG. 2 is a defocus distance and confocal differential curve provided by an embodiment of the present invention
The invention is described in further detail below with reference to the figures and specific examples.
Detailed Description
The invention is further described below by means of specific embodiments.
Fig. 1 is an architecture diagram of a differential auto-focusing measurement system, which includes: light sources (point light sources, parallel light sources, as long as they are distributed on the periphery of the field of view) are used for emitting illumination light; 2 collimating lens group (for leveling incident raySo that the horizontal parallel light is emitted); 3 first beam splitter (incident light reflection, measurement light transmission); 4 objective (for measuring objects); 5, measuring the object; 6, a tube mirror; 7 second beam splitter (split into two optical paths, for two cameras); 8 first optical sensor (position placed before light convergence point d) 1 Position) 9 second optical sensor (position placed after the light ray convergence point d) 2 At (c); an aperture diaphragm is arranged in front of the 2 collimating lens group, the 8 first optical sensor and the 9 second optical sensor and used for realizing confocal measurement.
The values of d1 and d2 are related to the magnification of the objective lens, and the linear region on the differential curve is smaller as the magnification is larger, so the values of d1 and d2 are required to satisfy the linear region of the object-side differential curve.
Furthermore, here 6 tube mirrors; 7 the positions of the two structures of the second spectroscope can be interchanged, and the normal use of the system is not influenced.
The light source 1 emits focusing light (parallel light or point light, four light sources are distributed at four corners of an observation field), the light generated by the light source 1 can be straightened through the straightening lens group 2 to generate parallel light, the parallel light is reflected through the first spectroscope 3 and is converged on the surface of the sample 5 through the objective lens 4, the focusing light is reflected on the surface of the sample 5, the focusing light is converted into the parallel light through the objective lens 4, the parallel light passes through the spectroscope 3 and starts to be converged through the objective lens 6, the converging light generated by the tube lens 6 is divided into the first photosensitive device 8 and the second photosensitive device 9 through the second spectroscope 7, the defocusing amount of the sample 5 is judged through the light intensity difference between the first photosensitive device 8 and the second photosensitive device 9, and focusing is realized if the light intensity difference is 0.
In confocal images, the axial light intensity satisfies the formula:
wherein u is the axial defocusing amount of an object space, and I (u) is an axial light intensity value; the axial differential measurement is to obtain two axial light intensity response curves deviating from the positive focal plane and equidistant before and after the focal plane and make a difference:
u F the pre-focal offset and the post-focal offset are obtained;
in the actual measurement process, the measurement plane is not a standard plane, and a certain spatial rotation exists, and the plane is inclined to a certain extent, so that the measurement precision and accuracy in the field of view can be ensured only by realizing that most regions in the field of view are in a focusing state to ensure high-precision measurement.
The light source 1 can be a parallel light source or a point light source; the light source can be four independent scattered light sources, or light sources with certain intervals which are reflected or spontaneously generated by other optical periods; the number of the polishing is not limited to four, and can be more or less;
in the embodiment of the invention, the first photosensitive device is a front-focus camera, and the second photosensitive device is a back-focus camera.
The positions of the objective lens 6 and the second spectroscope 7 can be interchanged, the focusing principle and the implementation process are not influenced, and only after the positions are interchanged, an eyepiece is needed in front of the objective lens 6 and the second spectroscope 7;
defocus u between camera and focal plane F The zoom lens is not limited to 3, and can be actually adjusted according to the magnification of the objective lens; for the magnifying objective lenses with different multiples, different differential measurement ranges are provided, so that the object defocusing amount needs to be dynamically adjusted according to the actual effective differential ranges of the objective lenses with different multiples.
The defocus distance of each point source can be obtained, and the spatial position of a focal plane can be determined by calculating a plurality of points (generally three points) on a plane.
The defocus distance of a single point is related to the confocal differential curve, as shown in fig. 2, when the point is located at the focal plane, the light intensity difference of the object-side dual-camera is zero, and otherwise, the defocus amount can be solved according to the middle linear region.
In the actual measurement process, the measurement plane is not a standard plane, and a certain spatial rotation exists, and the plane is inclined to a certain extent, so that the measurement precision and accuracy in the field of view can be ensured only by realizing that most areas in the field of view are in a focusing state to ensure high-precision measurement.
The invention provides a differential automatic focusing measuring method, which utilizes the conjugate relation of camera imaging before and after focusing to find the functional relation between the light intensity difference and the defocusing amount of a sample in the defocusing state; the method can calculate the defocusing amount of the measured object by acquiring the image once, and realizes quick focusing.
The method calculates the average defocusing amount by shooting a plurality of point light sources, improves the focusing accuracy and also improves the universality.
The above description is only an embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made by using the design concept should fall within the scope of infringing the present invention.
Claims (4)
1. A differential auto-focus measurement method, comprising: a differential auto-focusing measuring system specifically comprises: the method comprises the following steps: the device comprises a light source, a collimating lens group, a first spectroscope, an objective lens, a tube lens, a second spectroscope, a first optical sensor and a second optical sensor;
the light source is used for emitting illumination light, and the collimating lens group is used for emitting horizontal parallel light which is used for emitting transaction illumination light; the first spectroscope is used for reflecting incident light in the horizontal parallel light and measuring light transmission; the objective lens is used for measuring an object; the tube lens is used for converging light rays; the second spectroscope is used for dividing light into two light paths to be incident on the first optical sensor and the second optical sensor; the first optical sensor is positioned in front of the light convergence point d 1 Where the second optical sensor is positioned behind the light converging point d 2 At least one of (1) and (b);
the light source emits focusing light, the focusing light passes through the straightening lens group to be straightened to generate parallel light, the parallel light is reflected by the first spectroscope and is converged on the surface of a sample through the objective lens, the focusing light is reflected by the surface of the sample, the focusing light is converted into the parallel light through the objective lens, the parallel light passes through the spectroscope and starts to be converged through the objective lens, the converging light generated by the tube lens is divided into the first photosensitive device and the second photosensitive device through the second spectroscope, the defocusing amount of the sample is judged through the light intensity difference between the first photosensitive device and the second photosensitive device, and if the light intensity difference is 0, focusing is achieved.
2. The differential auto-focus measuring method of claim 1, wherein the light source is a parallel light source or a point light source.
3. The differential autofocus measurement method of claim 1, wherein the objective lens and the second beam splitter are interchangeable, and after the interchangeable positions, an eyepiece is placed in front of both the objective lens and the second beam splitter.
4. The differential auto-focus measuring method according to claim 1, wherein the first photosensitive device is a pre-focus camera and the second photosensitive device is a post-focus camera.
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| CN202210821339.2A CN115128763A (en) | 2022-07-13 | 2022-07-13 | Differential automatic focusing measuring method |
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| CN202210821339.2A CN115128763A (en) | 2022-07-13 | 2022-07-13 | Differential automatic focusing measuring method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116774496A (en) * | 2023-07-03 | 2023-09-19 | 西安电子科技大学杭州研究院 | Phase shift detection automatic focusing device and method for color double-hole modulation |
Citations (5)
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|---|---|---|---|---|
| US5317142A (en) * | 1991-11-18 | 1994-05-31 | Olympus Optical Co., Ltd. | Automatic focusing apparatus which removes light reflected by a lower surface of a sample |
| US5737084A (en) * | 1995-09-29 | 1998-04-07 | Takaoka Electric Mtg. Co., Ltd. | Three-dimensional shape measuring apparatus |
| JP2007147749A (en) * | 2005-11-24 | 2007-06-14 | Nikon Corp | Focus detecting device and automatic focusing device |
| JP2009074875A (en) * | 2007-09-19 | 2009-04-09 | Nikon Corp | Measuring device, and method of measuring the same |
| CN109799595A (en) * | 2017-11-16 | 2019-05-24 | 长光华大基因测序设备（长春）有限公司 | A kind of the inspection focus adjustment method and device of gene sequencer microcobjective |
-
2022
- 2022-07-13 CN CN202210821339.2A patent/CN115128763A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5317142A (en) * | 1991-11-18 | 1994-05-31 | Olympus Optical Co., Ltd. | Automatic focusing apparatus which removes light reflected by a lower surface of a sample |
| US5737084A (en) * | 1995-09-29 | 1998-04-07 | Takaoka Electric Mtg. Co., Ltd. | Three-dimensional shape measuring apparatus |
| JP2007147749A (en) * | 2005-11-24 | 2007-06-14 | Nikon Corp | Focus detecting device and automatic focusing device |
| JP2009074875A (en) * | 2007-09-19 | 2009-04-09 | Nikon Corp | Measuring device, and method of measuring the same |
| CN109799595A (en) * | 2017-11-16 | 2019-05-24 | 长光华大基因测序设备（长春）有限公司 | A kind of the inspection focus adjustment method and device of gene sequencer microcobjective |
Non-Patent Citations (1)
| Title |
|---|
| DINGRONG YI;ZHIQUN LIU;LINGHUA KONG;XINGXING ZHU;WEI JIANG: "A Parallel Differential Confocal Method for Highly Precise Surface Height Measurements", IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 32, no. 7, 1 April 2020 (2020-04-01), pages 375 - 378, XP011776215, DOI: 10.1109/LPT.2020.2973649 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116774496A (en) * | 2023-07-03 | 2023-09-19 | 西安电子科技大学杭州研究院 | Phase shift detection automatic focusing device and method for color double-hole modulation |
| CN116774496B (en) * | 2023-07-03 | 2024-04-16 | 西安电子科技大学杭州研究院 | Phase shift detection automatic focusing device and method for color double-hole modulation |
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