CN114636678A - Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof - Google Patents
Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof Download PDFInfo
- Publication number
- CN114636678A CN114636678A CN202210260901.9A CN202210260901A CN114636678A CN 114636678 A CN114636678 A CN 114636678A CN 202210260901 A CN202210260901 A CN 202210260901A CN 114636678 A CN114636678 A CN 114636678A
- Authority
- CN
- China
- Prior art keywords
- light
- sample
- reflector
- optical fiber
- refractive index
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 title claims abstract description 10
- 239000013307 optical fiber Substances 0.000 claims abstract description 38
- 230000003287 optical effect Effects 0.000 claims abstract description 25
- 150000001875 compounds Chemical class 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
-
- 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
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
- G01B11/0675—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating using interferometry
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention provides a refractometer capable of measuring crystal thickness and group refractive index and a working method thereof, wherein the refractometer capable of measuring crystal thickness and group refractive index comprises a light source, an optical fiber collimator, a 2 x 2 optical fiber coupler, a lens, a reflector, a grating and a CCD camera which are sequentially connected by an optical path. The optical fiber coupler is connected with a grating light path; the grating is connected with a CCD camera optical path; the CCD camera is connected with an upper computer. The invention provides non-contact and high-precision group refractive index measurement, has the advantages of simple structure, small volume, convenient operation and the like, and can measure the thickness value while measuring the group refractive index.
Description
The technical field is as follows:
the invention relates to a refractometer capable of measuring group refractive index and thickness of crystal and a working method thereof.
Background art:
the traditional group refractive index measuring instrument has the advantage of high measuring precision, but has the problems of large volume and strict requirements on the conditions for measuring crystals.
The invention content is as follows:
in order to overcome the defects of the existing refractometer, the invention provides a refractometer capable of measuring the group refractive index and the thickness of a crystal and a working method thereof.
In order to achieve the purpose, the invention adopts the technical scheme that: a refractometer for measuring group refractive index and thickness of a crystal, characterized in that: the device comprises an upper computer, a first lens, a sample, a first reflector, a second lens, a 2X 2 optical fiber coupler, an optical fiber collimator, a light source, a slit, a third reflector, a grating, a cylindrical lens and a CCD camera; the optical path of the first port of the 2 x 2 optical fiber coupler sequentially passes through the light source and the optical fiber collimator, the optical path of the second port of the 2 x 2 optical fiber coupler sequentially passes through the first lens, the sample and the first reflector, the optical path of the third port of the 2 x 2 optical fiber coupler sequentially passes through the second lens and the second reflector, the optical path of the fourth port of the 2 x 2 optical fiber coupler sequentially passes through the slit, the third reflector connection, the grating, the cylindrical lens and the CCD camera, and the CCD camera is electrically connected with the upper computer;
the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator; the parallel light is divided into two beams of light with equal power through a 2X 2 optical fiber coupler, wherein one beam of light is sample light, and the other beam of light is reference light; the sample light is focused on the sample through the first lens, then is transmitted to the first reflector through the sample, and the reference light is transmitted to the second reflector through the second lens; when two beams of light with certain optical path difference are superposed, interference is generated; the generated interference signal is expanded by the grating according to the wavelength and is acquired by a CCD camera; and analyzing the interference signal captured by the CCD camera through an upper computer, and calculating to obtain the group refractive index and the thickness of the sample.
Furthermore, light output from the fourth port of the 2 × 2 fiber coupler is emitted to a third reflector through a slit, then is emitted to a grating after being reflected by the third reflector, and then passes through a cylindrical lens and a CCD camera.
The invention also provides a working method of the refractometer based on the group refractive index and the thickness of the measurable crystal, which comprises the following steps:
step S1: the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator;
step S2: the parallel light is divided into two beams of light with equal power through an optical fiber coupler, wherein one beam of light is sample light, and the other beam of light is reference light; the sample light sequentially passes through the first lens and the sample and is emitted to the first reflector, and the reference light passes through the second lens and is emitted to the second reflector; when two beams of light with certain optical path difference are superposed, interference is generated;
step S3: the generated interference signal is expanded by a reticle grating according to the wavelength and captured by a CCD camera, and the average light intensity is sensed by the CCD camera, so that the light intensity after the two beams of light are superposed can be expressed as follows under the condition that the phase difference of the two beams of light is not changed all the time:
in the formula (I), the compound is shown in the specification,
and is the amplitude of the light wave,
is the phase difference of the light wave,
and
the light intensity of the two beams of light, n is the refractive index of the light in the propagation medium,
and
the optical paths of the two beams of light from the light source to the meeting point are respectively;
step S4: carrying out fast Fourier transform on the interference signal to obtain information of one axial direction of the sample, and analyzing the periodicity of the interference fringes of the axial information to determine the relative positions of the sample and the reflector;
step S5: acquiring an interference signal when no sample is placed, recording interference signal periodicity information a generated by a reflector, acquiring the interference signal when the sample is placed, eliminating a signal caused by self-coherence, recording interference signal periodicity information b generated by the upper surface of the sample, interference signal periodicity information c generated by the lower surface of the sample and interference signal periodicity information d generated by the reflector; analyzing the variation of the periodicity through two pieces of interference information to obtain the thickness value of the sample to be detected, wherein the thickness value of the sample to be detected can be calculated as follows:
in the formula, T is the thickness value of the sample to be measured,
the difference in the values of the periods of the mirrors with or without the sample,
is the difference value of the periodicity of the reflected light signals of the front and back surfaces of the object to be measured, f is the resolution of the refractometer,
is the refractive index of air.
Step S6: analyzing an interference signal when the sample is placed, and obtaining the optical path difference of two beams of light through the system resolution, thereby obtaining the group refractive index of the sample to be measured:
wherein n is the group refractive index of the sample to be measured.
Compared with the prior art, the invention has the following beneficial effects: compared with the traditional common refractometer, the invention can achieve high-precision and non-contact measurement on the premise of ensuring simple structure, small volume and convenient operation of the instrument, has low requirement on the measurement sample, and can simultaneously measure the thickness value of the sample while measuring the refractive index of the group.
Description of the drawings:
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is an image of the interference results of an embodiment of the present invention without a sample;
FIG. 3 is an image of the interference results of an embodiment of the present invention with a sample;
the upper computer in the figure, 2, a first lens, 3, a sample, 4, a first reflector, 5, a second reflector, 6, a second lens, 7.2 x 2 optical fiber coupler, 8, optical fiber collimator, 9, light source, 10, slit, 11, a third reflector, 12, grating, 13, cylindrical lens, 14, CCD camera.
The specific implementation mode is as follows:
the invention is further explained below with reference to the figures and the specific embodiments.
The refractometer has the advantages that the conditions of high precision, simple instrument structure and convenience in operation cannot be met by the traditional refractometer at the same time, and the refractometer has the possibility of damage to detection materials, is high in precision, free of contact, simple in equipment and convenient and fast to operate, and can measure the refractive index and the thickness of a crystal group at the same time.
Fig. 1 is a schematic diagram of the structural principle of an embodiment of the present invention.
A refractometer capable of measuring group refractive index and thickness of a crystal comprises an upper computer 1, a first lens 2, a sample 3, a first reflector 4, a second reflector 5, a second lens 6, a 2 x 2 optical fiber coupler 7, an optical fiber collimator 8, a light source 9, a slit 10, a third reflector 11, a grating 12, a cylindrical lens 13 and a CCD camera 14; the optical path of the first port of the 2 × 2 optical fiber coupler 7 sequentially passes through a light source 9 and an optical fiber collimator 8, the optical path of the second port of the 2 × 2 optical fiber coupler 7 sequentially passes through a first lens 2, a sample 3 and a first reflector 4, the optical path of the third port of the 2 × 2 optical fiber coupler 7 sequentially passes through a second lens 6 and a second reflector 5, the optical path of the fourth port of the 2 × 2 optical fiber coupler sequentially passes through a slit 10, a third reflector 11, a grating 12, a cylindrical lens 13 and a CCD camera 14, and the CCD camera 14 is electrically connected with the upper computer 1;
the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator; the parallel light is divided into two beams of light with equal power through a 2X 2 optical fiber coupler, wherein one beam of light is sample light, and the other beam of light is reference light; the sample light is focused on the sample through the first lens, then is transmitted to the first reflector through the sample, and the reference light is transmitted to the second reflector through the second lens; when two beams of light with certain optical path difference are superposed, interference is generated; the generated interference signal is expanded by the grating according to the wavelength and is acquired by a CCD camera; and analyzing the interference signal captured by the CCD camera through an upper computer, and calculating to obtain the group refractive index and the thickness of the sample.
Further, light output from the fourth port of the 2 × 2 fiber coupler is emitted to the third reflecting mirror 11 through the slit, then emitted to the grating 12 after being reflected by the third reflecting mirror 11, and then emitted to the CCD camera 14 through the cylindrical lens 13.
The embodiment also provides a method for eliminating the phased difference two-way line array spectral domain OCT device of the OCT conjugate mirror image based on the above, which comprises the following steps:
step S1: the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator;
step S3: the generated interference signal is expanded by a reticle grating according to the wavelength and captured by a CCD camera, and the average light intensity is sensed by the CCD camera, so that the light intensity after the two beams of light are superposed can be expressed as follows under the condition that the phase difference of the two beams of light is not changed all the time:
in the formula (I), the compound is shown in the specification,
and
is the amplitude of the light wave and,
is the phase difference of the light wave,
and
the light intensity of the two beams of light, n is the refractive index of the light in the propagation medium,
and
the optical paths of the two beams from the light source to the meeting point are respectively.
Step S4: carrying out fast Fourier transform on the interference signal to obtain information of one axial direction of the sample, and analyzing the periodicity of the interference fringes of the axial information to determine the relative positions of the sample and the reflector;
step S5: the method comprises the steps of obtaining interference signals when no sample is placed, recording interference signal periodicity information a generated by a reflector, obtaining the interference signals when the sample is placed, eliminating signals caused by self-coherence, recording interference signal periodicity information b generated by the upper surface of the sample, interference signal periodicity information c generated by the lower surface of the sample and interference signal periodicity information d generated by the reflector. Analyzing the variation of the periodicity through two pieces of interference information to obtain the thickness value of the sample to be detected, wherein the thickness value of the sample to be detected can be calculated as follows:
in the formula, T is the thickness value of the sample to be measured,
the difference in the values of the periods of the mirrors with or without the sample,
is the difference value of the periodicity of the reflected light signals of the front and back surfaces of the object to be measured, f is the resolution of the refractometer,
is the refractive index of air.
Step S6: analyzing an interference signal when the sample is placed, and obtaining the optical path difference of two beams of light through the system resolution, thereby obtaining the group refractive index of the sample to be measured:
wherein n is the group refractive index of the sample to be measured.
In this embodiment, the interference signal images measured with or without the glass sample are shown in fig. 2 and fig. 3, and different peak points can be seen from the images, so that the relative position relationship between the sample and the mirror can be analyzed.
The above embodiments are provided only for illustrating the present invention, and those skilled in the art can make various changes or modifications without departing from the scope of the present invention, since all equivalent technical solutions should also fall within the scope of the present invention.
Claims (3)
1. A refractometer for measuring group refractive index and thickness of a crystal, characterized in that: the device comprises an upper computer, a first lens, a sample, a first reflector, a second lens, a 2X 2 optical fiber coupler, an optical fiber collimator, a light source, a slit, a third reflector, a grating, a cylindrical lens and a CCD camera; the optical path of the first port of the 2 x 2 optical fiber coupler sequentially passes through the light source and the optical fiber collimator, the optical path of the second port of the 2 x 2 optical fiber coupler sequentially passes through the first lens, the sample and the first reflector, the optical path of the third port of the 2 x 2 optical fiber coupler sequentially passes through the second lens and the second reflector, the optical path of the fourth port of the 2 x 2 optical fiber coupler sequentially passes through the slit, the third reflector connection, the grating, the cylindrical lens and the CCD camera, and the CCD camera is electrically connected with the upper computer;
the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator; the parallel light is divided into two beams of light with equal power through a 2X 2 optical fiber coupler, wherein one beam of light is sample light, and the other beam of light is reference light; the sample light is focused on the sample through the first lens, then is transmitted to the first reflector through the sample, and the reference light is transmitted to the second reflector through the second lens; when two beams of light with certain optical path difference are superposed, interference is generated; the generated interference signal is expanded by the grating according to the wavelength and is acquired by a CCD camera; and analyzing the interference signal captured by the CCD camera through an upper computer, and calculating to obtain the group refractive index and the thickness of the sample.
2. The refractometer according to claim 1, wherein said refractometer is capable of measuring group refractive index and thickness of a crystal: and light output from the fourth port of the 2 x 2 optical fiber coupler is emitted to a third reflector through a slit, then is emitted to a grating after being reflected by the third reflector, and then passes through a cylindrical lens and a CCD camera.
3. A method of operating a refractometer based on the group refractive index and thickness of the measurable crystal of claim 1, wherein: the method comprises the following steps:
step S1: the light emitted by the light source is collimated into a beam of parallel light by the optical fiber collimator;
step S2: the parallel light is divided into two beams of light with equal power through an optical fiber coupler, wherein one beam of light is sample light, and the other beam of light is reference light; the sample light sequentially passes through the first lens and the sample and is emitted to the first reflector, and the reference light passes through the second lens and is emitted to the second reflector; when two beams of light with certain optical path difference are superposed, interference is generated;
step S3: the generated interference signal is expanded by a reticle grating according to the wavelength and captured by a CCD camera, and the average light intensity is sensed by the CCD camera, so that the light intensity after the two beams of light are superposed can be expressed as follows under the condition that the phase difference of the two beams of light is not changed all the time:
in the formula (I), the compound is shown in the specification,
and
is the amplitude of the light wave and,
is the phase difference of the light wave,
and
the light intensity of the two beams of light, n is the refractive index of the light in the propagation medium,
and
the optical paths of the two beams of light from the light source to the meeting point are respectively;
step S4: carrying out fast Fourier transform on the interference signal to obtain information of one axial direction of the sample, and analyzing the periodicity of the interference fringes of the axial information to determine the relative positions of the sample and the reflector;
step S5: acquiring an interference signal when no sample is placed, recording interference signal periodicity information a generated by a reflector, acquiring the interference signal when the sample is placed, eliminating a signal caused by self-coherence, recording interference signal periodicity information b generated by the upper surface of the sample, interference signal periodicity information c generated by the lower surface of the sample and interference signal periodicity information d generated by the reflector; analyzing the variation of the periodicity through two pieces of interference information to obtain the thickness value of the sample to be detected, wherein the thickness value of the sample to be detected can be calculated as follows:
in the formula, T is the thickness value of the sample to be measured,
the difference in the values of the periods of the mirrors with or without a sample,
is the difference value of the cycle number of the reflected light signals of the front surface and the back surface of the object to be measured, f is the resolution of the refractometer,
is the refractive index of air;
step S6: analyzing an interference signal when the sample is placed, and obtaining the optical path difference of two beams of light through the system resolution, thereby obtaining the group refractive index of the sample to be measured:
wherein n is the group refractive index of the sample to be measured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210260901.9A CN114636678A (en) | 2022-03-17 | 2022-03-17 | Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210260901.9A CN114636678A (en) | 2022-03-17 | 2022-03-17 | Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114636678A true CN114636678A (en) | 2022-06-17 |
Family
ID=81949844
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210260901.9A Pending CN114636678A (en) | 2022-03-17 | 2022-03-17 | Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114636678A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2452005Y (en) * | 2000-12-08 | 2001-10-03 | 中国科学院上海光学精密机械研究所 | Laser interferometer for simultaneously measuring thickness and refractive index |
| CN101261116A (en) * | 2008-04-20 | 2008-09-10 | 华中科技大学 | Thin film thickness and refractivity optical measurement method and its device |
| CN105115940A (en) * | 2015-09-08 | 2015-12-02 | 福州大学 | Curve measuring method and device for refractive index of optical material |
| WO2019183838A1 (en) * | 2018-03-28 | 2019-10-03 | 深圳市太赫兹科技创新研究院 | Optical coherence tomography system |
| CN113175887A (en) * | 2021-05-17 | 2021-07-27 | 苏州中科行智智能科技有限公司 | Device and method for measuring thickness and refractive index of thin film |
| CN113483679A (en) * | 2021-07-06 | 2021-10-08 | 东北大学秦皇岛分校 | Contact lens parameter measuring device and method |
-
2022
- 2022-03-17 CN CN202210260901.9A patent/CN114636678A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2452005Y (en) * | 2000-12-08 | 2001-10-03 | 中国科学院上海光学精密机械研究所 | Laser interferometer for simultaneously measuring thickness and refractive index |
| CN101261116A (en) * | 2008-04-20 | 2008-09-10 | 华中科技大学 | Thin film thickness and refractivity optical measurement method and its device |
| CN105115940A (en) * | 2015-09-08 | 2015-12-02 | 福州大学 | Curve measuring method and device for refractive index of optical material |
| WO2019183838A1 (en) * | 2018-03-28 | 2019-10-03 | 深圳市太赫兹科技创新研究院 | Optical coherence tomography system |
| CN113175887A (en) * | 2021-05-17 | 2021-07-27 | 苏州中科行智智能科技有限公司 | Device and method for measuring thickness and refractive index of thin film |
| CN113483679A (en) * | 2021-07-06 | 2021-10-08 | 东北大学秦皇岛分校 | Contact lens parameter measuring device and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102944169B (en) | A kind of synchronous polarization phase-shifting interferometer | |
| CN101983313A (en) | Apparatus and method for measuring surface topography of an object | |
| CN110057543B (en) | Wave surface measuring device based on coaxial interference | |
| WO2013091584A1 (en) | Method and device for detecting defects in substrate | |
| CN110160624B (en) | Optical fiber point diffraction device for three-dimensional vibration measurement and measurement method | |
| CN114812889A (en) | Large-caliber optical element stress detection device and detection method thereof | |
| JP2892075B2 (en) | Measuring method of refractive index distribution and transmitted wavefront and measuring device used for this method | |
| CN111964580B (en) | Device and method for detecting position and angle of film based on optical lever | |
| CN106840008B (en) | Optical fiber spacing measurement system and measurement method | |
| CN112684462A (en) | Amplified area array sweep frequency measuring device and method | |
| CN110631510B (en) | High-precision angle measuring device and method based on Michelson structure | |
| WO2020135891A1 (en) | Laser parallelism detector | |
| CN105674875A (en) | Full visual field low frequency heterodyne point diffraction interferometer | |
| CN108982510A (en) | Utilize 90 ° of optics mixer Surface profiling dynamic detection systems and method | |
| CN114894123B (en) | High-precision optical wedge angle measuring device and measuring method thereof | |
| CN113820051B (en) | Complementary interference stress measuring device for material | |
| CN108318736B (en) | Non-contact type measuring device and method for response frequency of piezoelectric ceramic | |
| CN116026244A (en) | System for measuring lens group lens surface spacing and refractive index | |
| CN114636678A (en) | Refractometer capable of measuring group refractive index and thickness of crystal and working method thereof | |
| CN101825435A (en) | All-fiber-optic displacement measuring method and device thereof | |
| CN205538737U (en) | High depth of field surface defect detecting device of optical element of reflection -type dual wavelength holography | |
| CN112816989A (en) | Distance measuring system | |
| CN112711029A (en) | Area array sweep frequency measuring device and method | |
| CN112711030A (en) | Microscope area array sweep frequency measuring device and method | |
| JPS6271804A (en) | Film thickness measuring instrument |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |