CN102620907B - A Method for Measuring the Phase Delay Angle of an Optical Device - Google Patents

Abstract

The invention discloses a method for measuring the phase delay angle of an optical device. The detection device is composed of a detection light source, a polarizing polarizer, a 1/4 wave plate, an optical device to be detected, and a polarized light azimuth detection component. Through the state changes before and after the phase delay device under test, the phase delay angle of the device under test can be obtained. It is suitable for polarization optical systems, ellipsometry, laser technology and other polarization-related measurement and detection fields. The principle of this method is described as follows: when the elliptically polarized light whose major axis is in the horizontal or vertical direction passes through optical devices with different phase retardation angles, the direction of the major axis of the transmitted or reflected polarized light will be different. By measuring the transmitted or reflected light The phase delay angle of the device under test can be deduced from the azimuth angle of the major axis, so as to realize the measurement of the polarization characteristics of the device under test.

Description

A Method for Measuring the Phase Delay Angle of an Optical Device

technical field

The invention relates to a method for measuring the polarization transfer matrix of an optical element to be tested, in particular to a device and a method for measuring the polarized light direction to obtain the phase delay of the device under test.

Background technique

With the deepening of the research on the polarization of light, people gradually realize the wide application prospect of polarization information, and the polarization technology has also begun to enter the practical stage. By detecting the polarization information of the reflected light of the target to invert the relevant information of the target to be measured, the measurable information of the target to be measured can be increased from the original dimension to three dimensions. The polarization information measurement has been used in ground object remote sensing detection and atmospheric detection. , underwater detection, astronomical detection, medical diagnosis, target detection, image processing and military applications are widely used. At the same time, with the maturity of single-photon detection technology, high-efficiency single-photon detectors have been technically realized. The development of single-photon detection technology has led to the rapid development of single-photon polarization applications. At present, free-space quantum security based on polarization encoding Communication is one of the important applications of single photon polarization.

The wave plate is one of the most commonly used polarization optical devices in the field of polarization research. The wave plate is also called a phase retarder. Its application covers the entire field of polarized light application technology, and its application prospects are very broad. With the deepening of polarization applications, people have put forward higher requirements for the accuracy of the phase retarder. How to accurately measure the retardation of the phase retarder is one of the key technologies that need to be solved. This has a great impact on the processing accuracy of the phase retarder. It is of decisive significance to improve the performance of polarized optical instruments. At present, in the application of engineering technology, the phase retarder is usually made of materials with birefringence effect such as quartz crystal, mica or _electro -optic crystal _. λ is proportional to λ, where ne _and n _o are the refractive indices of extraordinary light and ordinary light of crystal materials, d is the thickness of the wave plate, and λ is the wavelength of incident light. How to measure and monitor the phase retardation of the actual wave plate during processing It is one of the keys to the further development of polarized light application technology.

The present invention is based on the theory of polarized optics. When elliptically polarized light whose long axis is in the horizontal or vertical direction passes through optical devices with different phase retardation angles, the long axis direction of the outgoing polarized light will be different. By measuring the long axis of the outgoing light The azimuth angle is used to deduce the phase delay angle of the device under test, so as to realize the measurement of the polarization characteristics of the device under test. The method can also be applied to the process monitoring of the specific phase retardation wave plate, and its application prospect is broad.

Contents of the invention

The object of the present invention is to provide a method for measuring the phase delay angle of an optical device, and propose a method of measuring the state change before and after the detection light source passes through the phase delay device to be measured, and finally detecting the azimuth angle of the long axis of the outgoing light. The relative phase delay angle of the device can be tested. This test system can realize the relative phase delay measurement of the transmission or reflection optical elements, and can be applied in the design and processing of various wave plates.

The detection device of the inventive method is as shown in accompanying drawing 1: detection device comprises detection light source 1, polarizing polarizer 2, 1/4 wave plate 3, optical device to be tested 4, analyzer polarizer 51, drives analyzer to rotate And a motor 52 and an optical detector 53 that can record the angle. The wavelength of the detection light source 1 is consistent with the use wavelength of the final device; the polarizing polarizer 2 is at a certain angle α, which is not ±45°, and the use band of the polarizer covers the wavelength of the detection light source 1 ; The azimuth angle of the 1/4 wave plate 3 is at 0° or 90°, and the use wavelength of the wave plate is consistent with the test light source; the optical device 4 to be tested can be reflective or transmissive to the target beam, The same incident light can be oblique incidence or normal incidence; described analyzer polarizer 51 is identical with polarizer 2, and described rotating motor 52 can record the angle that polarizer rotates, and described optical detector 5 is to test light source for energy detection,

The specific measurement steps of the detection method for the phase delay angle of the optical device are as follows:

1) After the detection light source 1 passes through the polarizing film 2, it produces linearly polarized light at a certain angle α, and the angle is not ±45°. At this time, the Jones vector of the polarized light can be expressed as $\left(\begin{array}{c}\cos \mathrm{\α}\\ \sin \mathrm{\α}\end{array}\right);$

2) When the linearly polarized light passes through the 1/4 wave plate 3 with an azimuth angle of 0° or 90°, when the azimuth angle is 0°, the linearly polarized light becomes elliptically polarized light after passing through the wave plate, and the elliptically polarized light can be expressed as for $\left(\begin{array}{c}\cos \mathrm{\α}\\ -i\sin \mathrm{\α}\end{array}\right);$

同时预先测量该器件对S、P光的反射率或透射率，其效率表示为

步骤2中产生的椭偏光经过待测器件之后，其偏振状态可以表示为 $\left(\begin{array}{c}{T}_s\cos \mathrm{\α}\\ T_p\sin \mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right);$ 3) The relative phase delay angle of the optical device 4 to be tested is taken as δ, this angle is the quantity to be measured, and the range of the phase delay angle is

At the same time, the reflectance or transmittance of the device to S and P light is measured in advance, and its efficiency is expressed as

After the ellipsometric light generated in step 2 passes through the device under test, its polarization state can be expressed as $\left(\begin{array}{c}{T}_{\mathrm{the\; s}}\cos \mathrm{\α}\\ T_p\sin \mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right);$

及线偏光的方位角度α，待测光学器件(4)的相位延迟角δ与出射光方位角θ的关系满足：4) The polarized light azimuth angle measurement component (5) detects the polarized light state in step 3, and measures the azimuth angle of the polarized light as θ. By knowing the light transmission efficiency of S and P light in advance

and the azimuth angle α of the linearly polarized light, the relationship between the phase retardation angle δ of the optical device to be tested (4) and the azimuth angle θ of the outgoing light satisfies:

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}^{\mathrm{<span\; class="notranslate">p</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">s</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="tan"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">tan</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The specific principle of this method is as follows:

In optical theory, polarized light is divided into linearly polarized light, circularly polarized light and elliptically polarized light. Any kind of polarized light can be expressed as the superposition of two linearly polarized light vectors along the x-axis and y-axis, which can be expressed by Jones vector, specifically as follows:

为X、Y分量的相位，两分量之间的相位延迟为 Where E _x and E _y represent the complex amplitudes of X and Y components respectively, and a _x and a _y are the real amplitudes of X and Y components,

is the phase of the X and Y components, and the phase delay between the two components is

For the Jones vector $\left(\begin{array}{c}{a}_x\\ a_{\mathrm{the\; y}}{e}^{\mathrm{i\&delta;}}\end{array}\right)$ Under the indicated polarization state, the azimuth angle θ corresponding to the elliptically polarized light satisfies the following relationship with a _x , a _y and phase delay δ:

$\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="tan"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">tan</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

同时预先测量该器件对S、P光的反射率或透射率，其效率表示为

则各偏振光学元件的传输矩阵描述如下：In the optical path shown in Figure 1, the detection light source 1 passes through the polarizing plate 2 with an azimuth angle of α, the 1/4 wave plate 3 with an azimuth angle of 0 degrees, the optical device 4 to be tested, and finally passes through the polarized light azimuth Angle detection component 5 detects. Simultaneously assuming that the phase retardation angle to be measured of the optical device 4 to be tested is δ, and its range satisfies

At the same time, the reflectance or transmittance of the device to S and P light is measured in advance, and its efficiency is expressed as

Then the transmission matrix of each polarization optical element is described as follows:

1. The transmission matrix of the polarizing film 2 with an azimuth angle of α is: $\left(\begin{array}{cc}{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}& \sin \mathrm{\&alpha;}\cos \mathrm{\&alpha;}\\ \sin \mathrm{\&alpha;}\cos \mathrm{\&alpha;}& {\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}\end{array}\right)$

2. The transmission matrix of the 1/4 wave plate 3 with the azimuth angle at 0 degrees is: $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right)$

3. The transmission matrix of the optical device 4 to be tested is: $\left(\begin{array}{cc}{T}_{\mathrm{the\; s}}& 0\\ 0& T_p{e}^{-\mathrm{i\&delta;}}\end{array}\right)$

Suppose the polarization state of the incident light is $\left(\begin{array}{c}{\mathrm{E.}}_x\\ {\mathrm{E.}}_{\mathrm{the\; y}}\end{array}\right),$ Where E _x and E _y represent the complex amplitudes of the X and Y components respectively, then the polarization state of the incident light after passing through the above three optical elements can be expressed as:

$\left(\begin{array}{cc}{T}_{\mathrm{the\; s}}& 0\\ 0& T_p{e}^{-\mathrm{i\&delta;}}\end{array}\right)\left(\begin{array}{cc}1& 0\\ 0& -\mathrm{<figure-callout\; id="2"\; label="i\; cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">i</figure-callout>}& \\ \end{array},\right)\left(\begin{array}{c}{\cos }^{}\end{array}\right)\left(\begin{array}{cc}{}^2\mathrm{\&alpha;}& \sin \mathrm{\&alpha;}\cos \mathrm{\&alpha;}\\ \sin \mathrm{\&alpha;}\cos \mathrm{\&alpha;}& {\sin }^2\mathrm{\&alpha;}\end{array}\right)\left(\begin{array}{c}{\mathrm{E.}}_x\\ {\mathrm{E.}}_{\mathrm{the\; y}}\end{array}\right)$ (4)

$<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span>\left(\begin{array}{c}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\\ {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}\end{array}\right)$

At this time, the azimuth angle of the elliptically polarized light to be detected and the polarized light $\left(\begin{array}{c}{T}_{\mathrm{the\; s}}\cos \mathrm{\&alpha;}\\ T_p\sin \mathrm{\&alpha;}{e}^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right)$ Consistent, and according to the formula (3), it can be seen that the azimuth angle θ and the phase delay δ of this polarized light satisfy the following relationship:

$\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="tan"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">tan</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}^{\mathrm{<span\; class="notranslate">p</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">s</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

then the phase delay angle $\mathrm{\&delta;}=a\sin \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_p^{}{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}-T_{\mathrm{the\; <figure-callout\; id="2"\; label="s"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">s</figure-callout>}}^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}}{T_{\mathrm{the\; s}}{T}_p\cos \mathrm{\&alpha;}\sin \mathrm{\&alpha;}}\mathrm{the\; <figure-callout\; id="2"\; label="tan"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">tan</figure-callout>}2\mathrm{\&theta;}\right).$

This method provides a kind of thought that obtains the relative phase retardation angle of device by measuring the outgoing polarized light direction, and the advantage of this method is: 1) the measuring device of the present invention is simple in structure; 2) this inventive method can be used for measuring the device The phase delay can also be used to monitor the processing of the characteristic phase delay device; 3) the device of the invention is cheaper than the device for monitoring the phase delay angle with an interferometer during the processing of the specific angle phase delay wave plate .

Description of drawings

Figure 1: Diagram of the detection setup for phase delay angle measurement of optical devices.

Figure 2: Under the same optical efficiency of the devices under test S and P, the phase delay angle varies with the azimuth angle of the outgoing polarized light at different polarization angles; the curve a in the figure indicates that the phase delay varies with the incident polarization angle of 30° The change curve of the azimuth angle of the outgoing polarized light, curve b shows the change curve of the phase delay with the azimuth angle of the outgoing polarized light when the incident polarization angle is 40°.

Detailed ways

The implementation examples of the method of the present invention will be described in detail below in conjunction with the accompanying drawings.

The main devices adopted in the embodiment of the present invention are described as follows:

Composed of detection light source, 1/4 wave plate, optical device to be tested, analyzer polarizer and optical detector,

1) Detection light source 1: The detection light source adopts a domestic power adjustable laser, and the test wavelength is 850nm;

2) Polarizer 2 and Analyzer 51: the polarizer adopts Thorlabs' product, the model is LPVIS100, its main performance parameters: the working band is 600-1200nm; the polarization extinction ratio of the whole band is 10000:1, and the polarization extinction at 850nm The ratio is 100000:1; the caliber is 25mm, and the effective caliber is 90% of the caliber;

3) 1/4 wave plate 3: Thorlabs' achromatic 1/4 wave plate, model AQWP05M-980, its main performance parameters: working band is 700-1200nm; phase delay accuracy λ/40-λ/230;

4) Optical device 4 to be tested: adopt Daheng Optoelectronics Co., Ltd. broadband depolarizing beamsplitter BS, model GCC-403112, its main performance parameters: material K9; incident light angle 0±2°, reflectivity/transmittance: 48 /48±5%, |T _s -T _p |<5%, |R _s -R _p |<5%;

5) Rotating motor 52: The rotating motor adopts Thorlabs' product, the model is PRM1Z8E, its main performance parameters: 360° rotation; angular resolution ±0.1°; angular repeatability ±0.3°, maximum rotation speed 25°/S;

6) Optical detector 53: The optical detector adopts the power meter of Thorlabs Company, the model is PM120D, its main performance parameters: the working band is 400-1100nm; the power test range is 50nw-50mw; the probe is Si detector.

The main optical path schematic diagram of the inventive method is as shown in accompanying drawing 1, and specific situation is described as follows:

1) After the outgoing light of the 850nm laser 1 passes through the polarizer 2 with an azimuth angle α of 30°, an ideal beam of linearly polarized light is produced. The linear polarization of the linearly polarized light is 100000:1, and the normalized Jones A vector can be expressed as $\left(\begin{array}{c}\cos \frac{\mathrm{\&pi;}}{6}\\ \sin \frac{\mathrm{\&pi;}}{6}\end{array}\right)=\left(\begin{array}{c}\sqrt{3}/2\\ 1/2\end{array}\right);$

2) When the ideal linearly polarized light passes through the 1/4 wave plate 3 with an azimuth angle of 0°, the transmission matrix of the wave plate is $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ The linearly polarized light becomes elliptically polarized light after passing through the wave plate, and the Jones amount of the elliptically polarized light is $\left(\begin{array}{c}\sqrt{3}/2\\ -1/2i\end{array}\right);$

由于该分光镜为消偏振的，其S、P光的反射率或透射率基本相等，其效率取为T²，则BS的传输矩阵为 $\left(\begin{array}{cc}T& 0\\ 0& T{e}^{-\mathrm{i\&delta;}}\end{array}\right),$ 此时步骤2中产生的椭偏光经过待测器件之后，其偏振状态可以表示为 $T\left(\begin{array}{c}\sqrt{3/2}\\ 1/2e^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right);$ 3) After the elliptically polarized light passes through the broadband depolarized beamsplitter prism BS4 to be measured, the azimuth angle of the elliptically polarized light will change. First, the relative phase delay angle of the broadband depolarized beamsplitter prism BS is taken as δ, which is the quantity to be measured, and The range of the phase delay angle is

Since the beam splitter is depolarized, the reflectivity or transmittance of the S and P light is basically equal, and its efficiency is taken as T ² , then the transmission matrix of the BS is $\left(\begin{array}{cc}T& 0\\ 0& T{e}^{-\mathrm{i\&delta;}}\end{array}\right),$ At this time, after the ellipsometric light generated in step 2 passes through the device under test, its polarization state can be expressed as $\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout>}\left(\begin{array}{c}\sqrt{3/2}\\ 1/2e^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right);$

4) The polarized light azimuth angle detection component (5) detects the polarization state in step 3 again, measures the azimuth angle of the polarized light by the analyzer polarizer (51), and records the azimuth angle θ by the rotating motor (52) , since the S and P light reflectance or transmittance of the depolarized BS are basically equal, and the angle α of the incident ray polarization is determined, the azimuth θ and the phase delay angle δ of the optical device to be tested (4) satisfy the following relationship:

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}^{\mathrm{<span\; class="notranslate">p</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">s</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}$

The phase delay angle δ satisfies:

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>$

Claims (1)

1. A method for measuring the phase retardation angle of an optical device. The detection light source (1) passes through the polarizing plate (2) to generate linearly polarized light at a certain angle α, and the azimuth angle of the linearly polarized light is 1/4 of 0 degrees. The wave plate (3) converts the elliptically polarized light whose major axis is in the horizontal or vertical direction, the elliptically polarized light passes through the optical device to be tested (4), and then is detected by the polarized light azimuth detection component (5), wherein the polarization detection component (5) It consists of an analyzer polarizer (51), a motor (52) that drives the analyzer polarizer to rotate and can record the angle, and an optical detector (53), and is characterized in that: the phase delay angle of the optical device is passed through the following data processing steps get: 1) The detection light source (1) produces linearly polarized light at a certain angle α after passing through the polarizing film (2), and the angle is not ±45°. At this time, the Jones vector of the polarized light is expressed as $\left(\begin{array}{c}\cos \mathrm{\&alpha;}\\ \sin \mathrm{\&alpha;}\end{array}\right);$ 2) When the linearly polarized light passes through the 1/4 wave plate (3) with an azimuth angle of 0° or 90°, when the azimuth angle is 0°, the transmission matrix of the 1/4 wave plate is $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ Linearly polarized light becomes elliptically polarized light after passing through the wave plate, and its Jones vector is $\left(\begin{array}{c}\cos \mathrm{\&alpha;}\\ -i\sin \mathrm{\&alpha;}\end{array}\right);$ 3) The relative phase delay angle of the optical device (4) to be tested is taken as δ, this angle is to be measured, and the range of the phase delay angle is taken as

At the same time, the reflectance or transmittance of the device to S and P light is measured in advance, and its efficiency is expressed as

Then the transmission matrix of the optical device under test is $\left(\begin{array}{cc}{T}_{\mathrm{the\; s}}& 0\\ 0& T_p{e}^{-\mathrm{i\&delta;}}\end{array}\right),$ After the elliptically polarized light generated in step 2 passes through the device under test, its polarization state is expressed as $\left(\begin{array}{c}{T}_{\mathrm{the\; s}}\cos \mathrm{\&alpha;}\\ T_p\sin {\mathrm{\&alpha;e}}^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right);$ 4) The polarized light azimuth angle detection component (5) detects the polarization state in step 3), measures the azimuth angle of the polarized light through the analyzer polarizer (51), and records the azimuth angle through the rotating motor (52) The angle θ of , the azimuth angle θ and the phase delay angle δ of the optical device to be tested (4) satisfy the relationship: $\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ By knowing the light transmission efficiency of S and P light in advance

and the azimuth angle α of the linearly polarized light, then the azimuth angle θ of the outgoing light and the phase retardation angle δ of the optical device to be tested (4) satisfy a one-to-one relationship: $\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

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