CN109187433A - Refractive index of transparent films with double-prisms measuring device and method based on space interference - Google Patents
Refractive index of transparent films with double-prisms measuring device and method based on space interference Download PDFInfo
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- CN109187433A CN109187433A CN201810974484.8A CN201810974484A CN109187433A CN 109187433 A CN109187433 A CN 109187433A CN 201810974484 A CN201810974484 A CN 201810974484A CN 109187433 A CN109187433 A CN 109187433A
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- 238000000034 method Methods 0.000 title claims abstract description 10
- 230000010287 polarization Effects 0.000 claims abstract description 28
- 230000008878 coupling Effects 0.000 claims abstract description 22
- 238000010168 coupling process Methods 0.000 claims abstract description 22
- 238000005859 coupling reaction Methods 0.000 claims abstract description 22
- 239000000835 fiber Substances 0.000 claims abstract description 8
- 238000005259 measurement Methods 0.000 claims abstract description 5
- 239000010408 film Substances 0.000 claims abstract 6
- 230000003071 parasitic effect Effects 0.000 claims abstract 2
- 239000010409 thin film Substances 0.000 claims abstract 2
- 230000003287 optical effect Effects 0.000 claims description 17
- 238000010586 diagram Methods 0.000 claims description 2
- 239000013307 optical fiber Substances 0.000 abstract description 13
- 238000000691 measurement method Methods 0.000 abstract description 6
- 239000012528 membrane Substances 0.000 description 11
- 239000000463 material Substances 0.000 description 7
- 239000005357 flat glass Substances 0.000 description 6
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 238000009738 saturating Methods 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- 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
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- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
本发明公开了一种基于空间干涉的透明薄膜折射率测量装置及方法，搭建宽带光源(1)、起偏器(2)、保偏光纤(3)、平凸透镜(4)、作为迈克尔干涉仪的分束器(7)、光谱仪(11)以及控制与数据采集电路(12)的测量装置；利用作为迈克尔逊干涉仪移动臂进行扫描，实现对保偏光纤的空间分布寄生偏振耦合的测量，得到干涉耦合图像；步骤(3)、计算移动臂上反射镜的扫描移动距离Δs，计算出被测透明薄膜折射率nm。与现有技术相比，本发明可对等厚度的薄膜进行测量，精确度高；装置结构简单，测量方法操作简便。
The invention discloses a device and method for measuring the refractive index of a transparent thin film based on spatial interference. A broadband light source (1), a polarizer (2), a polarization-maintaining optical fiber (3), a plano-convex lens (4), and a Michael interferometer are constructed. The beam splitter (7), the spectrometer (11) and the measurement device of the control and data acquisition circuit (12) are used for scanning; the measurement of the spatially distributed parasitic polarization coupling of the polarization maintaining fiber is realized by using the moving arm as a Michelson interferometer, The interference coupling image is obtained; in step (3), the scanning moving distance Δs of the mirror on the moving arm is calculated, and the refractive index nm of the measured transparent film is calculated. Compared with the prior art, the present invention can measure films of equal thickness, with high precision; the device has a simple structure and the measurement method is easy to operate.
Description
Technical field
The present invention relates to optical device fields, more particularly to a kind of optical device materials refractive index measurement method.
Background technique
Refractive index is one of important parameter of optical material, is the important foundation for studying other optical properties of optical material；
Directly affect the quality of optical system.Refractive index can reflect many information inside optical material, meanwhile, other some parameters
(such as thermo-optical coeffecient, elasto-optical coefficient) is also closely related with refractive index.Therefore, measuring to the refractive index of certain material has
Highly important meaning.
Patent CN106970045 proposes " a kind of transmission-type coating substances apparatus for measuring refractive index ", describes " coupling optical
The light of module output is convergence or divergence form, has different incidence angles in the first prism measuring surface, different enters
Firing angle causes the light energy of lens different, and the light greater than critical angle is totally reflected, and the light less than critical angle reflects, so that
There is the transmitted light projected from the second prism the hot spot of terminator to calculate to be measured according to the corresponding relationship of itself and determinand
The refractive index of object ".Patent CN106840002 proposes " a kind of contactless plate glass thickness and apparatus for measuring refractive index and side
Method ", describe that " its measuring device includes source of parallel light, plate glass, the first line array CCD and the second line array CCD, source of parallel light
The incident beam directive plate glass of injection, the propagation path of incident beam are equipped with slit, and the first line array CCD is set to incident light
Beam is on the path of surface of plate glass back reflection light beam, and the second line array CCD is set on the extended line of incident beam, First Line
Battle array CCD and the second line array CCD are connect with digital storage oscilloscope, are obtained source of parallel light by oscillograph collection voltages peak and are issued
Incident light by plate glass once fold light, the reflected light of upper surface, following table surface launching light through upper surface reflect out
It is emitted directly toward the abscissa positions of the light of the second line array CCD when penetrating light, taking plate glass away, calculates refraction by position coordinates
Rate ".
Summary of the invention
The technical issues of based on the above-mentioned prior art, the transparent membrane refraction based on space interference that the invention proposes a kind of
Rate measuring device and method, the moving distance of Michael's interferometer moving arm caused by being changed according to optical path difference, realize measured object
The calculating of refractive index.
A kind of refractive index of transparent films with double-prisms measuring device based on space interference of the invention, including wideband light source 1, the polarizer
2, polarization maintaining optical fibre 3, plano-convex lens 4, the beam splitter 7 as Michael's interferometer, spectrometer 11, control and data acquisition circuit；
Tested transparent membrane 6 is installed between beam splitter 7 and fixed reflecting mirror 5 as Michael's interferometer；Wherein: wideband light source
The light of 1 outgoing becomes linearly polarized light after the polarizer 2, which is expanded after polarization maintaining optical fibre 3 by the first plano-convex lens 4
Beam collimation；Collimated light beam after expanding, which is inputted, is divided into two beams by beam splitter 7, is incident on respectively solid as Michelson's interferometer
The fixed reflecting mirror 5 of fixed arm and the packaged type reflecting mirror 8 of scan arm control packaged type reflecting mirror 8 by stepper motor 9
Movement, the optical path difference in polarization maintaining optical fibre 3 between two orthogonal polarized light beams is compensated by optical path difference between interferometer two-arm；Through
The interference light for crossing Michelson's interferometer is assembled by the second plano-convex lens 10, is obtained by spectrometer 11 and data acquisition circuit
The polarization coupled figure of polarization maintaining optical fibre 3.
A kind of refractive index of transparent films with double-prisms measurement method based on space interference of the invention, method includes the following steps:
The light that wideband light source is emitted is become linearly polarized light by step 1 after the polarizer, which passes through polarization-maintaining light
By 4 beam-expanding collimation of the first plano-convex lens after fibre；Collimated light beam after expanding, which is inputted, is divided into two beams by beam splitter, is incident on respectively
As the fixed reflecting mirror of Michelson's interferometer fixed arm and the packaged type reflecting mirror of scan arm；By tested transparent membrane
It is installed between beam splitter and fixed reflecting mirror as Michael's interferometer；
Step 2 is scanned using the packaged type reflecting mirror as Michelson's interferometer moving arm, is realized to mikey
The measurement of the space distributed polarization coupling of your polarization maintaining optical fibre obtains interference coupling image.Tested transparent membrane is installed, is obtained again
Interference coupling image.The abscissa of interference coupling image is number of scan points, and ordinate is interference strength；Extract the interference coupling of two width
Interfere number of scan points corresponding to primary maximum envelope maximum position in image, by number of scan points difference Δ p, calculates interference main pole
The mobile distance, delta s of big envelope, the i.e. mobile distance calculation formula of movable mirror are as follows:
Wherein, v is the mobile speed of packaged type reflecting mirror, and p is number of scan points system each second；
Step 3, the distance, delta s moved according to packaged type reflecting mirror, calculate tested refractive index of transparent films with double-prisms nm, formula
It is as follows:
Wherein, hmFor the thickness for being tested transparent membrane.
Compared with prior art, the present invention is based on the refractive index of transparent films with double-prisms measuring device and method of space interference, as
A kind of layer material refractive index measurement method based on polarization coupled, can the refractive index of transparent films with double-prisms to equal thickness accurately surveyed
Amount, accuracy are high；Apparatus structure is simple, and measurement method is easy to operate.
Detailed description of the invention
Fig. 1 is the layer material refractometry system of the invention based on polarization coupled；
Fig. 2 is the polarization coupled interference pattern obtained before and after being inserted into measured object, the interference obtained before the insertion of (2a) measured object
It couples the interference obtained after the insertion of image (2b) measured object and couples image；
Fig. 3 is the interference envelope diagram extracted, and (3a), (3b) are to extract the resulting image of envelope to (2a), (2b)；
Appended drawing reference:
1, wideband light source, 2, the polarizer, 3, polarization maintaining optical fibre, the 4, first plano-convex lens, 5, fixed reflecting mirror, 6, tested saturating
Bright film, 7, beam splitter, 8, packaged type reflecting mirror, 9, stepper motor, the 10, second plano-convex lens, 11, spectrometer.
Specific embodiment
Embodiments of the present invention are described in further detail below in conjunction with attached drawing.
It builds experimental provision as shown in Figure 1 and builds index path, by wideband light source 1, the polarizer 2, polarization maintaining optical fibre 3, first
Plano-convex lens 4, the beam splitter 7 as Michael's interferometer, spectrometer 11 and control and data acquisition circuit, composition, wherein
Tested transparent membrane 6 is installed between beam splitter 7 and fixed reflecting mirror 5 as Michael's interferometer；
The light that wideband light source 1 is emitted becomes linearly polarized light after the polarizer 2, and the linearly polarized light is after polarization maintaining optical fibre 3
4 beam-expanding collimation of plano-convex lens for being 15cm by focal length；Collimated light beam input beam splitter 7 after expanding is divided into two beams, respectively
It is incident on the packaged type reflecting mirror 8 of the fixed reflecting mirror 5 and scan arm as Michelson's interferometer fixed arm, passes through step
The movement that packaged type reflecting mirror 8 is controlled into motor 9 is compensated two in polarization maintaining optical fibre 3 by the optical path difference between interferometer two-arm
Optical path difference between orthogonal polarized light beam；It is saturating by the second plano-convex that focal length is 15cm by the interference light of Michelson's interferometer
Mirror 10 is assembled, and the polarization coupled figure of polarization maintaining optical fibre is obtained by spectrometer 11 and data acquisition circuit.Control and data acquisition electricity
Road is mainly by data collecting card NI-USB6251, AC-DC12V Switching Power Supply, for believing to NI-USB6251 power supply and difference
Number test macro.P0.0, P0.1, P0.2 mouth of data collecting card are controlled respectively at controllor for step-by-step motor power-on and power-off port, direction
Port processed, step angle port switching are connected, and realize the control to stepping electrode movement speed, distance；Data collecting card NI-
USB6251 data acquisition flow is by differential signal test macro, the voltage signal of photodetector output is quantified,
Coding, obtained digital signal is saved in capture card memory on board.
Refractive index of transparent films with double-prisms test device based on space interference, the transparent membrane folding of the invention based on space interference
Rate measurement method is penetrated, specifically includes the following steps:
Step 1 is scanned using the packaged type reflecting mirror 8 as Michelson's interferometer moving arm, is realized to advanced in years
The measurement of the space distributed polarization coupling of Ke Er polarization maintaining optical fibre obtains interference coupling image.Tested transparent membrane is installed, is obtained again
Interference coupling image is taken, the abscissa of interference coupling image is number of scan points, and ordinate is interference strength；Extract two width interference coupling
It closes and interferes number of scan points corresponding to primary maximum envelope maximum position in image, by number of scan points difference Δ p, calculate interference master
The mobile distance, delta s of very big envelope, the i.e. mobile distance of movable mirror, formula are as follows:
Wherein, v is the mobile speed of packaged type reflecting mirror, and p is number of scan points system each second；
When optical path difference caused by step 2, Δ s is equal to optical path difference caused by tested transparent membrane, i.e. 2 Δ s=2 (nm-1)hm
Inverse goes out tested refractive index of transparent films with double-prisms nm, wherein hmFor the thickness for being tested transparent membrane.
Embodiment:
Tested film is polyvinyl alcohol film, with a thickness of 30 μm.Tested film is mounted on Michelson's interferometer point
Between beam device and fixed reflecting mirror, the space beam splitting distributed polarization coupling of polarization maintaining optical fibre is measured, (2b) is obtained in Fig. 2
Shown in interference coupling image.The interference envelope that interference coupling is (2a) and (2b) of Fig. 2 is extracted by Hilbert transform algorithm,
Acquired results are shown in (3a) and (3b) of Fig. 3.Corresponding number of scan points at interference primary maximum envelope maximum intensity is calculated, scanning is passed through
It is 15.48 μm that points, which calculate the mobile distance of mobile mirror, and according to formula:
2 Δ s=2 (nm-1)hm
Obtain the refractive index 1.516 of transparent membrane.
Claims (2)
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810974484.8A CN109187433A (en) | 2018-08-24 | 2018-08-24 | Refractive index of transparent films with double-prisms measuring device and method based on space interference |
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| CN201810974484.8A CN109187433A (en) | 2018-08-24 | 2018-08-24 | Refractive index of transparent films with double-prisms measuring device and method based on space interference |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109916347A (en) * | 2019-04-16 | 2019-06-21 | 合肥工业大学 | A method for measuring the surface topography of silicon wafers based on near-infrared low coherence light |
| WO2023024467A1 (en) * | 2021-08-26 | 2023-03-02 | 五邑大学 | Crystal refractive index measurement method and apparatus, and storage medium |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050254057A1 (en) * | 2004-05-14 | 2005-11-17 | Alphonse Gerard A | Low coherence interferometry utilizing phase |
| CN103134776A (en) * | 2011-11-30 | 2013-06-05 | 中国计量学院 | Liquid refractive index absolute measurement sensor based on D-type polarization maintaining optical fibre |
| CN203720071U (en) * | 2014-01-27 | 2014-07-16 | 中国科学院上海光学精密机械研究所 | Polarization frequency domain optical coherence tomography system based on single detector |
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2018
- 2018-08-24 CN CN201810974484.8A patent/CN109187433A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050254057A1 (en) * | 2004-05-14 | 2005-11-17 | Alphonse Gerard A | Low coherence interferometry utilizing phase |
| CN103134776A (en) * | 2011-11-30 | 2013-06-05 | 中国计量学院 | Liquid refractive index absolute measurement sensor based on D-type polarization maintaining optical fibre |
| CN203720071U (en) * | 2014-01-27 | 2014-07-16 | 中国科学院上海光学精密机械研究所 | Polarization frequency domain optical coherence tomography system based on single detector |
Non-Patent Citations (2)
| Title |
|---|
| 张红霞等: "白光扫描干涉仪用于保偏光纤偏振耦合检测", 《红外与激光工程》 * |
| 杨修文等: "迈克尔逊干涉仪测量薄膜的折射率与厚度", 《郧阳师范高等专科学校学报》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109916347A (en) * | 2019-04-16 | 2019-06-21 | 合肥工业大学 | A method for measuring the surface topography of silicon wafers based on near-infrared low coherence light |
| WO2023024467A1 (en) * | 2021-08-26 | 2023-03-02 | 五邑大学 | Crystal refractive index measurement method and apparatus, and storage medium |
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