CN102620907B - Method for measuring phase delay angles of optical device - Google Patents

Abstract

The invention discloses a method for measuring phase delay angles of an optical device. A detection device consists of a detection light source, a polarizing polaroid, a 1/4 wave plate, the optical device to be measured and a polarized light azimuth angle detection component. The phase delay angles of the device to be measured can be acquired by measuring the state change of the detection light source which passes through a phase delay device to be measured. The method is suitable for the field of measurement and detection related to polarization such as the field of polarization optical systems and elliptical polarization measurement, laser technology and the like. The method has the principles that: when elliptically polarized light of which the long axis is in a horizontal or vertical direction passes through the optical devices at different phase delay angles, the directions of the long axes of transmitted or reflected polarized light are different, and the phase delay angles of the device to be measured are inferred inversely by measuring the long axis azimuth angles of the transmitted or reflected light, so that the polarization characteristics of the device to be measured are measured.

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 polarisation of light Journal of Sex Research, people recognize the wide application prospect of polarization information gradually, and polarization technology also starts to enter into practical stage.And by the catoptrical polarization information of the detection of a target, be finally inversed by the relevant information of target to be measured, can by target to be measured can measurement information amount increase again three-dimensional from original dimension, polarization information is measured at atural object remote sensing, atmospheric exploration, undersea detection, astrosurveillance, medical diagnosis, target detection, image and is processed and be used widely in the field such as Military Application.While reaching its maturity along with 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 is one of the most frequently used polarization optics device of polarization research field, and wave plate is also referred to as phase delay device, and its application has covered whole polarized light applied technical field, and application prospect is very extensive.Along with going deep into of polarization application, 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 solving, and this performance to the machining precision of phase delay chip and raising polarization optics instrument all has decisive meaning.In engineering technology application, the material that phase delay device adopts quartz crystal, mica or electro-optic crystal etc. to have birefringence effect is conventionally made at present, and its shape becomes parallel thin sheet, phase delay and 2 π (n _e-n _o) d/ λ is directly proportional, n wherein _e, n _ofor the refractive index of the non-ordinary light of crystalline material and ordinary light, d is wave plate thickness, and λ is 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 polarization optics theory, while utilizing the elliptically polarized light of major axis in horizontal or vertical direction to pass through the optical device of out of phase delay angle, the long axis direction of its outgoing polarized light can be different, by measuring the anti-phase delay angle that pushes away device under test of major axis orientation angle of emergent light, thereby realize the measurement to device under test polarization characteristic.The 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

A kind of method that the object of this invention is to provide measurement optics phase delay angle, proposed a kind of by measuring detection light source by the state variation before and after phase delay device to be measured, the mode that finally detects the major axis orientation angle of emergent light is known the relative phase delay angle of device under test, this test macro can be realized transmission or reflective optical devices are carried out to relative phase delay measurement, can be applied in the design process of various wave plates.

The pick-up unit of the inventive method is as shown in Figure 1: pick-up unit comprises detection light source 1, plays 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 wavelength of described detection light source 1 and the use consistent wavelength of resulting devices; Described plays inclined to one side polaroid 2 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; Described 4 pairs of target beams of 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 record the angle of polaroid rotation, and described 5 pairs of testing light sources of optical detector carry out energy measuring,

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

1) detection light source 1 produces the line polarisation of a certain angle [alpha] after playing inclined to one side polaroid 2, and this angle is in non-± 45 °, and now the Jones vector of polarized light can be expressed as $\left(\begin{array}{c}\cos \mathrm{\α}\\ \sin \mathrm{\α}\end{array}\right);$

2) this linearly polarized light is through position angle during the quarter wave plate 3 in 0 ° or 90 °, gets position angle while being 0 °, and linearly polarized light becomes elliptically polarized light after wave plate, and elliptically polarized light can be expressed as $\left(\begin{array}{c}\cos \mathrm{\α}\\ -i\sin \mathrm{\α}\end{array}\right);$

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

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

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

4) polarized light measurement of azimuth assembly (5) detects the polarized light state in step 3, and the position angle of measuring this polarized light is θ, by knowing in advance the throughput of S, P light

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 meet:

$\mathrm{\&delta;}=a\sin \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_p^{}{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}-T_s^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}}{T_s{T}_p\cos \mathrm{\&alpha;}\sin \mathrm{\&alpha;}}\tan 2\mathrm{\&theta;}\right)---\left(1\right)$

The concrete principle of this method is as follows:

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

E wherein _x, E _ythe complex amplitude that represents respectively X, Y component, and a _x, a _yfor the real amplitude of X, Y component,

for the phase place of X, Y component, the phase delay between two components is

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

$\tan 2\mathrm{\&theta;}=\frac{{2a}_x{a}_y}{a_x^2-a_y^2}\cos \mathrm{\&delta;}---\left(3\right)$

And in light path as shown in Figure 1, detection light source 1 is α through position angle respectively plays inclined to one side polaroid 2, quarter wave plate 3, the to be measured optical device 4 of position angle in 0 degree, finally by crossing polarized light position angle probe assembly 5, detect.The phase delay angle to be measured of simultaneously supposing optical device 4 to be measured is δ, and its scope meets

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

the transmission matrix of each polarization optical element is described below:

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

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

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

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

$=(E_x\cos \mathrm{\&alpha;}+E_y\sin \mathrm{\&alpha;})\left(\begin{array}{c}{T}_s\cos \mathrm{\&alpha;}\\ T_p\sin \mathrm{\&alpha;}{e}^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right)$

The now position angle of elliptically polarized light to be checked and polarized light $\left(\begin{array}{c}{T}_s\cos \mathrm{\&alpha;}\\ T_p\sin \mathrm{\&alpha;}{e}^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right)$ Unanimously, and known according to formula (3), the azimuth angle theta of this polarized light, that phase-delay quantity δ meets relation is as follows:

$\tan 2\mathrm{\&theta;}=\frac{T_s{T}_p\cos \mathrm{\&alpha;}\sin \mathrm{\&alpha;}}{{\mathrm{<figure-callout\; id="2"\; label="T\; p"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_p^{}{\sin }^2\mathrm{\&alpha;}-T_s^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}}\sin \mathrm{\&delta;}---\left(5\right)$

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

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

Accompanying drawing explanation

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

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

Embodiment

Below in conjunction with accompanying drawing, the embodiment of the inventive method is described in detail.

The main devices adopting in the embodiment of the present 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 domestic power tunable laser, tests as 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, at 850nm place polarization extinction ratio, is 100000: 1; Caliber size is 25mm, and effective aperture is bore 90%;

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; Power test scope is 50nw-50mw; Probe is Si detector.

As shown in Figure 1, concrete condition is described below the main optical path schematic diagram of the inventive method:

1) emergent light of 850nm laser instrument 1, through azimuth angle alpha after the polaroid 2 of 30 °, produces a branch of more satisfactory line polarisation, and the line degree of bias of this line polarisation is 100000: 1, and the normalization Jones vector of emergent light 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) this ideal line polarized light is through position angle when the quarter wave plate 3 of 0 °, and the transmission matrix of wave plate is $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ This linearly polarized light has become elliptically polarized light after by wave plate, and Jones of this elliptically polarized light is in right amount $\left(\begin{array}{c}\sqrt{3}/2\\ -1/2i\end{array}\right);$

3) elliptically polarized light is by after broadband depolarization Amici prism BS4 to be measured, the position angle of elliptically polarized light can change, the relative phase delay angle of first getting broadband depolarization Amici prism BS is δ, and this angle is amount to be measured, and the scope of getting this phase delay angle is

because this spectroscope is depolarization, its S, P reflection of light rate or transmissivity are substantially equal, and its efficiency is taken as T ², the transmission matrix of BS is $\left(\begin{array}{cc}T& 0\\ 0& T{e}^{-\mathrm{i\&delta;}}\end{array}\right),$ The ellipse polarisation now producing in step 2 is through after device under test, and 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) polarized light position angle probe assembly (5) detects the polarization state in step 3 again, by analyzing polaroid (51) measure this polarized light position angle, by electric rotating machine (52), record azimuth angle theta, because S, P light reflectivity or the transmissivity of depolarization BS are substantially equal, and the angle [alpha] of incident ray polarisation is definite, and the phase delay angle δ of azimuth angle theta and optical device to be measured (4) meets following relation:

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

Phase delay angle δ meets:

$\mathrm{\&delta;}=-a\sin \left(\frac{\sqrt{3}}{2}\mathrm{<figure-callout\; id="2"\; label="tan"\; filenames="HDA0000144718880000011.png"\; state="\{\{state\}\}">tan</figure-callout>}2\mathrm{\&theta;}\right)$

Claims (1)

1. the method for a measurement optics phase delay angle, detection light source (1) has been passed through the linearly polarized light that inclined to one side polaroid (2) produces a certain angle [alpha], this linearly polarized light is the quarter wave plate in 0 degree (3) by position angle, change into the elliptically polarized light of major axis in horizontal or vertical direction, this elliptically polarized light is through optical device to be measured (4), passing through polarized light position angle probe assembly (5) detects again, wherein Polarization Detection assembly (5) is by analyzing polaroid (51), drive the rotation of analyzing polaroid and motor (52) that can recording angular, optical detector (53) forms, it is characterized in that: optical device phase delay angle obtains by following data processing step:

1) detection light source (1) produces the linearly polarized light of a certain angle [alpha] after playing inclined to one side polaroid (2), and this angle is in non-± 45 °, and now the Jones vector of polarized light is expressed as $\left(\begin{array}{c}\cos \mathrm{\&alpha;}\\ \sin \mathrm{\&alpha;}\end{array}\right);$

2) this linearly polarized light is through position angle during the quarter wave plate (3) in 0 ° or 90 °, gets position angle while being 0 °, and the transmission matrix of quarter wave plate is $\left(\begin{array}{cc}1& 0\\ 0& -i\end{array}\right),$ Linearly polarized light becomes elliptically polarized light after 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 optical device to be measured (4) is taken as δ, and this angle is to be measured, and the scope of getting this phase delay angle is

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

the transmission matrix of optical device to be measured is $\left(\begin{array}{cc}{T}_s& 0\\ 0& T_p{e}^{-\mathrm{i\&delta;}}\end{array}\right),$ The elliptically polarized light producing in step 2 is through after device under test, and its polarization state is expressed as $\left(\begin{array}{c}{T}_s\cos \mathrm{\&alpha;}\\ T_p\sin {\mathrm{\&alpha;e}}^{-i(\mathrm{\&delta;}+\mathrm{\&pi;}/2)}\end{array}\right);$

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

$\tan 2\mathrm{\&theta;}=\frac{T_s{T}_p\cos \mathrm{\&alpha;}\sin \mathrm{\&alpha;}}{T_p^2{\sin }^2\mathrm{\&alpha;}-T_s^2{\cos }^2\mathrm{\&alpha;}}\sin \mathrm{\&delta;}---\left(1\right)$

By knowing in advance the throughput of S, P light

and the orientation angles α of linearly polarized light, the phase delay angle δ of the orientation angles θ of emergent light and optical device to be measured (4) meets relation one to one:

$\mathrm{\&delta;}=a\sin \left(\frac{T_p^2{\sin }^2\mathrm{\&alpha;}-T_s^2{\cos }^2\mathrm{\&alpha;}}{T_s{T}_p\cos \mathrm{\&alpha;}\sin \mathrm{\&alpha;}}\tan 2\mathrm{\&theta;}\right).---\left(2\right)$

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