CN102620907A - Method for measuring phase delay angles of 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 kind of method of measurement optics phase delay angle

Technical field

The present invention relates to a kind of method of measuring optical element polarization transmission matrix to be measured, be specifically related to a kind of device and method that direction of polarized light is obtained measured device phase delay of measuring.

Background technology

Along with the intensification to the polarisation of light Journal of Sex Research, people recognize the wide application prospect of polarization information gradually, and polarization technology also begins to enter into the practicability stage.And be finally inversed by the relevant information of target to be measured through detection of a target polarization of reflected light information; Can but the measurement information amount of target to be measured be increased three-dimensional again from original dimension, polarization information is measured and is used widely in fields such as atural object remote sensing, atmospheric exploration, undersea detection, astrosurveillance, medical diagnosis, target detection, Flame Image Process and military applications.While reaching its maturity along with the single-photon detecting survey technology; High efficiency single-photon detector can be realized technically; The development of single-photon detecting survey technology causes the fast development of single photon polarization application, and the free space quantum secret communication based on polarization encoder is exactly one of a kind of important application of single photon polarization at present.

Wave plate then is one of the most frequently used polarization optics device of polarization research field, and wave plate also is referred to as phase delay device, and its application has covered whole polarized light applied technical field, and application prospect very extensively.Go deep into along with what polarization was used; People also have higher requirement to the service precision of phase delay device; The retardation that how to accurately measure phase delay device is to need one of gordian technique that solves, and this all has decisive meaning to the machining precision of phase delay chip and the performance of raising polarization optics instrument.In engineering was used, the material that phase delay device adopts quartz crystal, mica or electro-optic crystal etc. to have birefringence effect usually formed at present, and its shape becomes the parallel thin sheet, phase delay and 2 π (n _e-n _o) d/ λ is directly proportional, n wherein _e, n _oBe the refractive index of non-ordinary light of crystalline material and ordinary light, d is a wave plate thickness, and λ is a lambda1-wavelength, and in process, phase-delay quantity how to measure and monitor actual wave plate is one of key of further developing of polarized light application technology.

The present invention is based on the polarization optics theory; When the elliptically polarized light that utilizes major axis to be in level or vertical direction passes through the optical device of out of phase delay angle; The long axis direction of its outgoing polarized light can be different; Major axis orientation angle through measuring emergent light is come the anti-phase delay angle that pushes away device under test, thereby realizes the measurement to the device under test polarization characteristic.This method can also be applied in the process monitoring of particular phases delay wave plate, and its application prospect is extensive.

Summary of the invention

The method that the purpose of this invention is to provide a kind of measurement optics phase delay angle; Proposed a kind of through measuring detection light source through the state variation before and after the phase delay device to be measured; The mode that detects the major axis orientation angle of emergent light is at last known the relative phase delay angle of device under test; This test macro can be realized the relative phase delay measurement is carried out in transmission or reflective optical devices, can be applied in the Design and Machining process of various wave plates.

The pick-up unit of the inventive method is shown in accompanying drawing 1: pick-up unit comprises detection light source 1, play inclined to one side polaroid 2, quarter wave plate 3, optical device to be measured 4, analyzing polaroid 51, drive checking bias slice rotation and motor 52, optical detector 53 that can recording angular.The use consistent wavelength of the wavelength of described detection light source 1 and resulting devices; Described inclined to one side polaroid 2 is in some angle [alpha], and this angle is in non-± 45 °, and the use wave band of polaroid covers the wavelength of detection light source 1 simultaneously; The position angle of described quarter wave plate 3 is in 0 ° or 90 °, and the use wavelength of this wave plate is consistent with testing light source; 4 pairs of target beams of described optical device to be measured can be reflection or transmission, and same incident light can be oblique incidence or vertical incidence; Described analyzing polaroid 51 is identical with polarizer slice 2, and described electric rotating machine 52 can write down the angle of polaroid rotation, and 5 pairs of testing light sources of described optical detector carry out energy measuring,

The concrete measuring process of detection method of this optical device phase delay angle is following:

1) detection light source 1 has been passed through the line polarisations that inclined to one side polaroid 2 backs produce a certain angle [alpha], and this angle is in non-± 45 °, and this moment, the Jones vector of polarized light can be expressed as $\left(\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ \mathrm{Sin}\mathrm{\α}\end{array}\right);$

When 2) this linearly polarized light is in the quarter wave plate 3 of 0 ° or 90 ° through the position angle, get the position angle when being 0 °, linearly polarized light becomes elliptically polarized light through behind the wave plate, and elliptically polarized light can be expressed as $\left(\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ -i\mathrm{Sin}\mathrm{\α}\end{array}\right);$

3) the relative phase delay angle of optical device 4 to be measured is taken as δ, and this angle is an amount to be measured, and the scope of getting this phase delay angle does Simultaneously measure this device in advance to S, P reflection of light rate or transmissivity, its efficient is expressed as

The ellipse polarisation that produces in the step 2 is through after the device under test, and its polarization state can be expressed as $\left(\begin{array}{c}{T}_s\mathrm{Cos}\mathrm{\α}\\ T_p\mathrm{Sin}\mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right);$

4) polarized light measurement of azimuth assembly (5) detects the polarized light state in the step 3; The position angle of measuring this polarized light is θ; The logical optical efficiency

through knowing S, P light in advance and the orientation angles α of line polarisation, the phase delay angle δ of optical device to be measured (4) and the relation of emergent light azimuth angle theta satisfy:

$\mathrm{\δ}=a\sin \left(\frac{T_p^2{\sin }^2\mathrm{\α}-T_s^2{\cos }^2\mathrm{\α}}{T_s{T}_p\cos \mathrm{\α}\sin \mathrm{\α}}\tan 2\mathrm{\θ}\right)---\left(1\right)$

The concrete principle of this method is following:

In optical theory, polarized light is divided into line polarisation, circularly polarized light and elliptically polarized light.Any polarized light can be expressed as the stack of light vector along two linearly polarized lights of x axle and y axle, can represent with Jones vector, the concrete expression as follows:

E wherein _x, E _yThe complex amplitude of representing X, Y component respectively, and a _x, a _yBe the real amplitude of X, Y component,

Be the phase place of X, Y component, the phase delay between two components does

For Jones vector $\left(\begin{array}{c}{a}_x\\ a_y{e}^{\mathrm{I\δ}}\end{array}\right)$ Under the represented polarization state, azimuth angle theta and a that this elliptically polarized light is corresponding _x, a _yAnd phase-delay quantity δ satisfies following relation:

$\tan 2\mathrm{\θ}=\frac{{2a}_x{a}_y}{a_x^2-a_y^2}\cos \mathrm{\δ}---\left(3\right)$

And in the light path as shown in Figure 1, detection light source 1 is quarter wave plate 3, the optical device to be measured 4 that the inclined to one side polaroid of rising of α 2, position angle are in 0 degree through the position angle respectively, detects through polarized light position angle probe assembly 5 at last.The phase delay angle to be measured of supposing optical device 4 to be measured simultaneously is δ; Its scope satisfies measures this device to S, P reflection of light rate or transmissivity simultaneously in advance, and its efficient is expressed as

then the transmission matrix of each polarization optical element be described below:

1, the position angle is that the transmission matrix that plays inclined to one side polaroid 2 of α is: $\left(\begin{array}{cc}{\mathrm{Cos}}^2\mathrm{\α}& \mathrm{Sin}\mathrm{\α}\mathrm{Cos}\mathrm{\α}\\ \mathrm{Sin}\mathrm{\α}\mathrm{Cos}\mathrm{\α}& {\mathrm{Sin}}^2\mathrm{\α}\end{array}\right)$

2, the position angle is in the transmission matrix of quarter wave plate 3 of 0 degree and is: $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right)$

3, the transmission matrix of optical device 4 to be measured is: $\left(\begin{array}{cc}{T}_s& 0\\ 0& T_p{e}^{-\mathrm{I\δ}}\end{array}\right)$

Suppose that the incident light polarization state does $\left(\begin{array}{c}{E}_x\\ E_y\end{array}\right),$ E wherein _x, E _yThe complex amplitude of representing X, Y component respectively, then incident light can be expressed as through the polarization state after above 3 optical elements:

$\left(\begin{array}{cc}{T}_s& 0\\ 0& T_p{e}^{-\mathrm{i\δ}}\end{array}\right)\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right)\left(\begin{array}{cc}{\cos }^2\mathrm{\α}& \sin \mathrm{\α}\cos \mathrm{\α}\\ \sin \mathrm{\α}\cos \mathrm{\α}& {\sin }^2\mathrm{\α}\end{array}\right)\left(\begin{array}{c}{E}_x\\ E_y\end{array}\right)$ (4)

$=(E_x\cos \mathrm{\α}+E_y\sin \mathrm{\α})\left(\begin{array}{c}{T}_s\cos \mathrm{\α}\\ T_p\sin \mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right)$

This moment elliptically polarized light to be checked position angle and polarized light $\left(\begin{array}{c}{T}_s\mathrm{Cos}\mathrm{\α}\\ T_p\mathrm{Sin}\mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right)$ Unanimity, and can know that according to formula (3) azimuth angle theta of this polarized light, phase-delay quantity δ satisfy relation as follows:

$\tan 2\mathrm{\θ}=\frac{T_s{T}_p\cos \mathrm{\α}\sin \mathrm{\α}}{T_p^2{\sin }^2\mathrm{\α}-T_s^2{\cos }^2\mathrm{\α}}\sin \mathrm{\δ}---\left(5\right)$

Phase delay angle then $\mathrm{\δ}=a\mathrm{Sin}\left(\frac{T_p^2{\mathrm{Sin}}^2\mathrm{\α}-T_s^2{\mathrm{Cos}}^2\mathrm{\α}}{T_s{T}_p\mathrm{Cos}\mathrm{\α}\mathrm{Sin}\mathrm{\α}}\mathrm{Tan}2\mathrm{\θ}\right).$

It is a kind of through measuring the thinking that the outgoing direction of polarized light is come acquisition device relative phase delay angle that this method provides, and the advantage of this method is: 1) measurement mechanism of the present invention is simple in structure; 2) this inventive method promptly can be used for the phase delay of measuring element, also can be used to monitor the process of characteristic phase delay device; 3) this contrive equipment is compared with the device of interferometer monitoring phase delay angle in the process that is used for special angle phase delay wave plate, and cost is cheaper.

Description of drawings

Fig. 1: the pick-up unit figure that optical device phase delay angle is measured.

Fig. 2: under device under test S, the P optical efficiency same case, phase delay angle is with the azimuthal change curve of outgoing polarized light light during different polarizing angle; Phase delay was with the azimuthal change curve of outgoing polarized light when curve a represented that the incidence polarizing angle is 30 ° among the figure, and phase delay was with the azimuthal change curve of outgoing polarized light when curve b represented that the incidence polarizing angle is 40 °.

Embodiment

Below in conjunction with accompanying drawing the embodiment of the inventive method is carried out detailed description.

The main devices that is adopted in the embodiment of the invention is described below:

Detection light source,, quarter wave plate, optical device to be checked, analyzing polaroid and optical detector form,

1) detection light source 1: detection light source adopts homemade adjustable power laser instrument, tests to be wavelength 850nm;

2) polarizer slice 2 and checking bias slice 51: polaroid adopts the product of Thorlabs, and model is LPVIS100, its Specifeca tion speeification: service band is 600-1200nm; Whole wave band polarization extinction ratio is 10000: 1, and polarization extinction ratio is 100000: 1 at the 850nm place; Caliber size is 25mm, and effective aperture is 90% of a bore;

3) quarter wave plate 3: adopt the achromatism quarter wave plate of Thorlabs, model is AQWP05M-980, its Specifeca tion speeification: service band is 700-1200nm; Phase delay accuracy λ/40-λ/230;

4) optical device 4 to be measured: adopt the broadband depolarization Amici prism BS of photoelectricity company of Daheng, model is GCC-403112, its Specifeca tion speeification: material K9; 0 ± 2 ° of incident angle of light, reflectivity/transmitance: 48/48 ± 5%, | T _s-T _p|＜5%, | R _s-R _p|＜5%;

5) electric rotating machine 52: electric rotating machine adopts the product of Thorlabs, and model is PRM1Z8E, its Specifeca tion speeification: can 360 ° of rotations; Angular resolution ± 0.1 °; Angle repeatable accuracy ± 0.3 °, 25 °/S of maximum rotative speed;

6) optical detector 53: optical detector adopts the power meter of Thorlabs company, and model is PM120D, its Specifeca tion speeification: service band is 400-1100nm; The power test scope is 50nw-50mw; Probe is the Si detector.

The main optical path synoptic diagram of the inventive method is shown in accompanying drawing 1, and concrete condition is described below:

1) after the emergent light of 850nm laser instrument 1 is in 30 ° polaroid 2 through azimuth angle alpha, produce a branch of more satisfactory line polarisation, the line degree of bias of this line polarisation is 100000: 1, and then the normalization Jones vector of emergent light can be expressed as $\left(\begin{array}{c}\mathrm{Cos}\frac{\mathrm{\π}}{6}\\ \mathrm{Sin}\frac{\mathrm{\π}}{6}\end{array}\right)=\left(\begin{array}{c}\sqrt{3}/2\\ 1/2\end{array}\right);$

When 2) this ideal line polarized light was in 0 ° quarter wave plate 3 through the position angle, the transmission matrix of wave plate did $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ This linearly polarized light has become elliptically polarized light after through wave plate, and Jones of this elliptically polarized light does in right amount $\left(\begin{array}{c}\sqrt{3}/2\\ -1/2i\end{array}\right);$

3) elliptically polarized light is through behind the broadband depolarization Amici prism BS4 to be measured; The position angle of elliptically polarized light can change; The relative phase delay angle of at first getting broadband depolarization Amici prism BS is δ, and this angle is an amount to be measured, and the scope of getting this phase delay angle does

Because this spectroscope is a depolarization, its S, P reflection of light rate or transmissivity are equal basically, and its efficient is taken as T ², then the transmission matrix of BS does $\left(\begin{array}{cc}T& 0\\ 0& T{e}^{-\mathrm{I\δ}}\end{array}\right),$ The ellipse polarisation that produce in the step 2 this moment is through after the device under test, and its polarization state can be expressed as $T\left(\begin{array}{c}\sqrt{3/2}\\ 1/2e^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right);$

4) polarized light position angle probe assembly (5) detects the polarization state in the step 3 again; Through analyzing polaroid (51) measure this polarized light the position angle, write down azimuth angle theta through electric rotating machine (52); Because S, P light reflectivity or the transmissivity of depolarization BS are equal basically; And the angle [alpha] of incident ray polarisation confirms that then the phase delay angle δ of azimuth angle theta and optical device to be measured (4) satisfies following relation:

$\tan 2\mathrm{\θ}=\frac{T_s{T}_p\cos \mathrm{\α}\sin \mathrm{\α}}{T_p^2{\sin }^2\mathrm{\α}-T_s^2{\cos }^2\mathrm{\α}}\sin \mathrm{\δ}=-\frac{\sqrt{3}}{2}\sin \mathrm{\δ}$

Phase delay angle δ satisfies:

$\mathrm{\δ}=-a\sin \left(\frac{\sqrt{3}}{2}\tan 2\mathrm{\θ}\right)$

Claims (1)

1. the method for a measurement optics phase delay angle; Detection light source (1) has been passed through the line polarisation that inclined to one side polaroid (2) produces a certain angle [alpha]; This line polarisation is in the quarter wave plate (3) of 0 degree through the position angle; Change into the elliptically polarized light that major axis is in level or vertical direction, this elliptically polarized light passes through polarized light position angle probe assembly (5) again and detects through optical device to be measured (4); Wherein polarization probe assembly (5) by analyzing polaroid (51), drive the checking bias slice rotation and motor (52), optical detector (53) that can recording angular be formed, it is characterized in that: optical device phase delay angle obtains through following data processing step:

1) detection light source (1) has been passed through the line polarisation that inclined to one side polaroid (2) back produces a certain angle [alpha], and this angle is in non-± 45 °, and this moment, the Jones vector of polarized light can be expressed as $\left(\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ \mathrm{Sin}\mathrm{\α}\end{array}\right);$

When 2) this linearly polarized light is in the quarter wave plate (3) of 0 ° or 90 ° through the position angle, get the position angle when being 0 °, the transmission matrix of quarter wave plate does $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ Linearly polarized light becomes elliptically polarized light through behind the wave plate, and its Jones vector does $\left(\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ -i\mathrm{Sin}\mathrm{\α}\end{array}\right);$

3) the relative phase delay angle of optical device to be measured (4) is taken as δ, and this angle is an amount to be measured, and the scope of getting this phase delay angle does

Simultaneously measure this device in advance to S, P reflection of light rate or transmissivity, its efficient is expressed as

Then the transmission matrix of optical device to be measured does $\left(\begin{array}{cc}{T}_s& 0\\ 0& T_p{e}^{-\mathrm{I\δ}}\end{array}\right),$ The ellipse polarisation that produces in the step 2 is through after the device under test, and its polarization state can be expressed as $\left(\begin{array}{c}{T}_s\mathrm{Cos}\mathrm{\α}\\ T_p\mathrm{Sin}\mathrm{\α}{e}^{-i(\mathrm{\δ}+\mathrm{\π}/2)}\end{array}\right);$

4) polarized light position angle probe assembly (5) detects the polarization state in the step 3) again; Through analyzing polaroid (51) measure this polarized light the position angle, write down azimuthal angle θ through electric rotating machine (52), the phase delay angle δ of azimuth angle theta and optical device to be measured (4) satisfies relation:

$\tan 2\mathrm{\θ}=\frac{T_s{T}_p\cos \mathrm{\α}\sin \mathrm{\α}}{T_p^2{\sin }^2\mathrm{\α}-T_s^2{\cos }^2\mathrm{\α}}\sin \mathrm{\δ}---\left(1\right)$

The logical optical efficiency

through knowing S, P light in advance and the orientation angles α of line polarisation, then the phase delay angle δ of the orientation angles θ of emergent light and optical device to be measured (4) satisfies relation one to one:

$\mathrm{\δ}=a\sin \left(\frac{T_p^2{\sin }^2\mathrm{\α}-T_s^2{\cos }^2\mathrm{\α}}{T_s{T}_p\cos \mathrm{\α}\sin \mathrm{\α}}\tan 2\mathrm{\θ}\right)---\left(2\right)$

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