CN112880973B - Device and method for improving grating period measurement precision - Google Patents
Device and method for improving grating period measurement precision Download PDFInfo
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- CN112880973B CN112880973B CN202110041338.1A CN202110041338A CN112880973B CN 112880973 B CN112880973 B CN 112880973B CN 202110041338 A CN202110041338 A CN 202110041338A CN 112880973 B CN112880973 B CN 112880973B
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- 238000005259 measurement Methods 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000005070 sampling Methods 0.000 claims abstract description 3
- 230000003287 optical effect Effects 0.000 claims description 4
- 230000001678 irradiating effect Effects 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/02—Testing optical properties
- G01M11/0242—Testing optical properties by measuring geometrical properties or aberrations
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses a device and a method for improving the measurement precision of a grating period, wherein the device comprises: the device comprises a laser, a first isolator, a second isolator, a plurality of reflectors, a rotary table and a detector, wherein the laser is used for emitting laser with a preset wavelength; the first isolator is provided with a first through hole through which the laser penetrates, and is used for preventing the laser from being reflected to the laser; the second isolator is provided with a second through hole, and the laser penetrates through the second through hole after passing through the first through hole; the plurality of reflectors are used for reflecting and changing the direction of the laser; the turntable is provided with a grating, and laser is reflected to the grating through a reflector and returns through the original path after being diffracted by the grating; the detector is used for sampling the diffracted light spots at the second through hole. The device for improving the measurement precision of the grating period is simple and easy to realize, and can effectively reduce the measurement uncertainty and improve the measurement precision.
Description
Technical Field
The invention relates to the technical field of optical measurement, in particular to a device and a method for improving grating period measurement precision.
Background
Diffraction gratings have a number of important applications in the fields of optical spectrum analysis, optical communication systems, AR/VR display technology, etc. In these practical applications, the machining accuracy of the diffraction grating is highly required. In the related technology, the principle of measuring the grating period by using a diffraction method can meet the preset precision requirement to a certain extent, but the alignment of the diffracted light is difficult to judge and has low precision because a mode of observing the alignment by naked eyes is adopted, and the rotation of a rotary table needs to be controlled by a stepping motor controller; especially when the revolving stage is close to the auto-collimation position, still need to carry out manual fine setting, it is more time-consuming and laboursome to operate, it is inconvenient. Therefore, there is room for improvement in the above techniques.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, an object of the present invention is to provide a device for improving the measurement accuracy of the grating period, which is simple and easy to implement, and can effectively reduce the measurement uncertainty and improve the measurement accuracy.
The invention also provides a method applied to the device for improving the grating period measurement precision.
The device for improving the grating period measurement accuracy according to the embodiment of the invention comprises:
the laser is used for emitting laser with a preset wavelength;
the laser isolator comprises a first isolator, wherein a first through hole is formed in the first isolator, the laser penetrates through the first through hole, and the first isolator is used for preventing the laser from being reflected to the laser;
the second isolator is provided with a second through hole, and the laser penetrates through the second through hole after passing through the first through hole;
a plurality of mirrors for reflecting and changing the direction of the laser light;
the laser is reflected to the grating through the reflector and is diffracted by the grating and then returns to the original path;
a detector for sampling the diffracted spots at the second through-hole.
The device for improving the measurement precision of the grating period is simple and easy to realize, and can effectively reduce the measurement uncertainty and improve the measurement precision.
According to the apparatus for improving the measurement accuracy of the grating period of the embodiment of the present invention, the turntable further includes: the grating support is used for fixing the grating.
According to the apparatus for improving the measurement accuracy of the grating period of the embodiment of the present invention, the turntable further includes: the grating support is fixed on the pitching table.
According to the device for improving the measurement accuracy of the grating period, provided by the embodiment of the invention, the preset wavelength is 633 nm.
According to the device for improving the grating period measurement accuracy, the reflector is a silver-plated reflector.
The device for improving the measurement precision of the grating period according to one embodiment of the invention further comprises: and the processor is connected with the detector and is used for processing the laser sampled by the detector.
The method for improving the measurement accuracy of the grating period according to the second aspect of the present invention is applied to the apparatus for improving the measurement accuracy of the grating period according to any one of the first aspect, and comprises the following steps:
s1, emitting laser with preset wavelength by a laser, passing through the first through hole and the second through hole, reflecting twice by a reflector to change the direction, and irradiating the laser to the position of the grating to be measured;
s2, fixing the grating to be measured on a grating support, and enabling the vertical axis of the front surface of the grating to be measured to coincide with the axis of the rotary table by adjusting the position of the grating support and the angle of the pitching table;
s3, controlling the turntable through a self-programming program to enable the incident light spot and the diffraction light spot irradiated on the front surface of the grating to be measured to be on the same straight line;
and S4, obtaining the double diffraction angle theta of the grating to be measured through the step S3, substituting the double diffraction angle theta into a grating equation, and calculating to obtain a grating period measurement value.
Further, the grating equation is:
wherein d is s For grating period measurements, λ 0 Calibrating the wavelength of light, n, for measuring light vacuum tpf The refractive index of air is shown, theta is twice the diffraction angle, and beta is the included angle between incident light and diffracted light in the plane perpendicular to the turntable.
In summary, the advantages of the method and the apparatus for improving the measurement accuracy of the grating period are the same as those of the prior art, and are not described herein again.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic structural diagram of an apparatus for improving the measurement accuracy of a grating period according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating the principles of a method for improving the accuracy of grating period measurements according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the principle of a method of improving the accuracy of grating period measurements according to an embodiment of the present invention;
FIG. 4 is a diagram of a position adjustment of a grating mount according to an embodiment of the present invention;
FIG. 5 is a flow chart of a method of improving grating period measurement accuracy according to an embodiment of the present invention.
Reference numerals:
100-a device for improving the measurement accuracy of the grating period, 1-a laser, 2-a first isolator, 21-a first through hole, 3-a second isolator, 31-a second through hole, 4-a reflector, 5-a turntable, 6-a grating, 7-a detector, 8-a processor and 9-a grating support.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "upper," "lower," "front," "rear," "left," "right," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be considered as limiting.
An apparatus 100 for improving the accuracy of grating period measurement according to an embodiment of the present invention is described below with reference to fig. 1-4. As shown in fig. 1, an apparatus 100 for improving the measurement accuracy of the grating period according to an embodiment of the present invention includes:
the laser device 1, specifically, the laser device 1 is used for emitting laser with a preset wavelength;
the first isolator 2, specifically, the first isolator 2 is provided with a first through hole 21, laser penetrates through the first through hole 21, and the first isolator 2 is used for preventing the laser from being reflected to the laser 1, so that the accuracy of a diffraction grating period measurement result is improved;
the second isolator 3 is further provided with a second through hole 31, so that on one hand, diffraction spots can be observed conveniently, on the other hand, the self-collimation effect can be achieved, and further, laser penetrates through the second through hole 31 after passing through the first through hole 21;
a plurality of mirrors 4, specifically, the plurality of mirrors 4 for reflectively changing the direction of the laser light; as shown in fig. 1, in a specific embodiment, two mirrors 4 may be provided in the apparatus 100 for improving the grating period measurement accuracy;
the turntable 5 is further provided with a grating 6, laser is reflected to the grating 6 through the reflector 4 and is diffracted by the grating 6 to return to the original path; thus, the rotation error can be reduced by the rotary table 5, and the diffraction angle error is greatly reduced;
the detector 7, specifically, the detector 7 can sample the diffracted light spot at the second through hole 31, thereby facilitating the realization of automatic acquisition and processing of images and improving the measurement accuracy.
The device 100 for improving the measurement accuracy of the grating period is simple and easy to implement, and can effectively reduce the measurement uncertainty and improve the measurement accuracy.
According to the apparatus 100 for improving the measurement accuracy of the grating period of the embodiment of the present invention, as shown in fig. 4, the turntable 5 may further include: the grating holder 9, in particular the grating holder 9, may be used to fix the grating 6, thereby keeping the grating 6 in the same attitude during the measurement.
It should be noted that the turntable 5 is a high-precision turntable 5, which is beneficial to ensuring the accuracy of the test result.
According to the device 100 for improving the measurement accuracy of the grating period in one embodiment of the present invention, the grating 6 to be measured can be placed on the grating support 9, and the light reflected by the laser is irradiated onto the grating 6, so that the light spots of different orders can be generated by the diffraction effect of the grating 6. Further, the detector 7 is used for automatically acquiring images, specifically, the optimal position can be obtained by analyzing and adjusting the program set in the detector 7, so that the period of the grating 6 can be rapidly output, and the method has the advantages of simple operation, easy realization, short time consumption and high precision.
It should be noted that the second through hole 31 is arranged in front of the laser 1, and when the laser beam is emitted to the reflector 4 through the second through hole 31, the laser beam is reflected to the grating 6 through the reflector 4, and then the light beam diffracted by the grating 6 returns along the original path, and the detector 7 can obtain the position of the light spot at the second through hole 31, thereby being beneficial to determining the overlapping condition of the light beam. Further, first isolator 2 sets up between laser instrument 1 and second isolator 3, can ensure through first isolator 2 like this that the light after the diffraction can return the original place and can not get into the laser instrument again, and then avoids disturbing the frequency of laser to promote the accuracy of experimental result.
According to the apparatus 100 for improving the measurement accuracy of the grating period of the embodiment of the present invention, the turntable 5 further includes: a pitching table (not shown) on which the grating support 9 can be fixed.
According to the apparatus 100 for improving the measurement accuracy of the grating period according to an embodiment of the present invention, the preset wavelength may be 633 nm.
According to the device 100 for improving the grating period measurement accuracy of the embodiment of the invention, the reflector 4 can be a silver-plated reflector 4, which is beneficial to improving the reflection effect of laser.
The apparatus 100 for improving the measurement accuracy of the grating period according to an embodiment of the present invention, as shown in fig. 1, further includes: the processor 8 is further connected to the detector 7, and the processor 8 processes the laser sampled by the detector 7. For example, in one embodiment, the processor 8 may be a computer, so that the laser light sampled by the detector 7 can be presented to the tester in the form of an image by the processor 8, thereby making the test result more intuitive.
In summary, the apparatus 100 for improving the measurement accuracy of the grating period according to the present invention is simple and easy to implement, and can effectively reduce the measurement uncertainty and improve the measurement accuracy.
The method for improving the measurement accuracy of the grating period according to the second aspect of the present invention is applied to the apparatus 100 for improving the measurement accuracy of the grating period according to any one of the first aspects, as shown in fig. 4, and includes the following steps:
s1, emitting laser with preset wavelength by the laser 1, passing through the first through hole 21 and the second through hole 31, reflecting twice by the reflector 4 to change the direction, and further irradiating the position of the grating 6 to be measured;
s2, fixing the grating 6 to be measured on the grating support 9, and enabling the vertical axis of the front surface of the grating 6 to be measured to coincide with the axis of the rotary table 5 by adjusting the position of the grating support 9 and the angle of the pitching table;
s3, controlling the turntable 6 through a self-programming program to enable the incident light spot and the diffraction light spot irradiated on the front surface of the grating 6 to be measured to be on the same straight line;
and S4, obtaining the double diffraction angle theta of the grating 6 to be measured through the step S3, substituting the double diffraction angle theta into the grating 6 equation, and calculating to obtain the period measurement value of the grating 6.
Further, the grating 6 equation is:
wherein d is s For grating 6 period measurements, λ 0 Calibrating the wavelength of light, n, for measuring light vacuum tpf And theta is the refractive index of air, is twice the diffraction angle, alpha is the diffraction angle, theta is 2 alpha, and beta is the included angle between incident light and diffracted light in a plane perpendicular to the turntable.
In summary, the method for improving the measurement accuracy of the grating period according to the second aspect of the present invention has the advantages of simplifying the measurement apparatus, improving the measurement accuracy of the grating period 6, and the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Claims (5)
1. An apparatus for improving the measurement accuracy of a grating period, comprising:
the laser is used for emitting laser with a preset wavelength;
the laser isolator comprises a first isolator, wherein a first through hole is formed in the first isolator, the laser penetrates through the first through hole, and the first isolator is used for preventing the laser from being reflected to the laser;
the second isolator is provided with a second through hole, and the laser penetrates through the second through hole after passing through the first through hole;
a plurality of mirrors for reflectively changing a direction of the laser light;
the laser is reflected to the grating through the reflector and is diffracted by the grating and then returns to the original path;
a detector for sampling the diffracted spots at the second through-hole;
the turntable further includes: the grating support is used for fixing the grating;
the turntable further includes: the grating support is fixed on the pitching table;
fixing the grating on the grating support, and enabling the vertical axis of the front surface of the grating to be measured to coincide with the axis of the rotary table by adjusting the position of the grating support and the angle of the pitching table;
controlling the turntable to enable the incident light spot and the diffraction light spot irradiated on the front surface of the grating to be detected to be on the same straight line;
obtaining a double diffraction angle theta of the grating to be detected,
by the grating equation:
calculating to obtain a measured value of the period of the grating to be measured;
wherein ds is the result of grating period measurement,
to measure the wavelength of the optical vacuum calibration light,
is a refractive index of air and is,
is the angle of the two-fold diffraction,
the included angle between the incident light and the diffracted light in the plane perpendicular to the rotary table.
2. The apparatus of claim 1, wherein the predetermined wavelength is 633 nm.
3. The apparatus of claim 1, wherein the mirror is a silvered mirror.
4. The apparatus for improving the measurement accuracy of the grating period according to any one of claims 1 to 3, further comprising: and the processor is connected with the detector and is used for processing the laser sampled by the detector.
5. A method for improving the measurement accuracy of the grating period, which is applied to the device for improving the measurement accuracy of the grating period according to any one of claims 1 to 4, comprises the following steps:
s1, emitting laser with preset wavelength by a laser, passing through the first through hole and the second through hole, reflecting twice by a reflector to change the direction, and irradiating the laser to the position of the grating to be measured;
s2, fixing the grating to be measured on a grating support, and enabling the vertical axis of the front surface of the grating to be measured to coincide with the axis of the rotary table by adjusting the position of the grating support and the angle of the pitching table;
s3, controlling the turntable through a self-programming program to enable the incident light spot and the diffraction light spot irradiated on the front surface of the grating to be measured to be on the same straight line;
and S4, obtaining the double diffraction angle theta of the grating to be measured through the step S3, substituting the double diffraction angle theta into a grating equation, and calculating to obtain a grating period measurement value.
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| CN111856636A (en) * | 2020-07-03 | 2020-10-30 | 中国科学技术大学 | Variable-pitch grating mask line density distribution controllable fine adjustment method |
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2021
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Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1515960A (en) * | 2003-08-22 | 2004-07-28 | 中国科学院上海光学精密机械研究所 | Mask for lithography containing nonlinear optical material layer |
| CN102822447A (en) * | 2010-05-21 | 2012-12-12 | 哈里伯顿能源服务公司 | Downhole spectroscopic detection of carbon dioxide and hydrogen sulfide |
| CN107966213A (en) * | 2016-10-20 | 2018-04-27 | 尚文涛 | A kind of measuring device, measuring method and the scaling method in diffraction grating cycle |
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