CN103472593A - Polarization modulator without moving part - Google Patents

Abstract

A polarization modulator without a moving part comprises an achromatic quarter-wave plate, an athermic multi-level phase retarder and a polarization beam splitter. The athermic multi-level phase retarder comprises a sapphire crystal and an MgF2 crystal. The sapphire crustal is located on the side close to the achromatic quarter-wave plate, the thickness ratio between the sapphire crystal and the MgF2 crystal is 1:2-1:3, the fast axis direction of the sapphire crystal is perpendicular to the fast axis direction of the MgF2, and the included angles between the two fast axis directions and the horizontal directions are both 45 degrees. The fast axis direction of the achromatic quarter-wave plate is perpendicular to the horizontal direction, and the fast axis direction of the polarization beam splitter is parallel to or perpendicular to the fast axis direction of the achromatic quarter-wave plate. By the utilization of the polarization modulator, a sine curve with the amplitude changing along with changing of the degree of polarization and the phase changing along with changing of the angle of polarization can be obtained on a probe. The polarization modulator has the advantages of being small in size, low in weight, free of the moving part, simple in demodulation algorithm, high in demodulation precision and the like.

Description

A kind of light polarization modulator of movement-less part

Technical field

The invention belongs to the aerospace optical remote sensing technical field, relate to a kind of light polarization modulator obtained for the target polarization information, be particularly suitable for the particles such as the cloud in planetary scale and gasoloid are surveyed.

Background technology

The application demand of the departments such as meteorology, atmosphere environment supervision, ocean, Aero-Space and military affairs, promoted the progress of satellite atmosphere remote sensing technology.The optical polarization remote sensing technology is the product that optical remote sensing technology is combined with the polarimetry technology.Due to the high precision characteristics of polarimetry, make the polarization remote sensing system can become the new technical means of satellite atmosphere remote sensing.

That China's commercial satellite has formed is meteorological, resource and ocean three large satellite series, and the environment small satellite constellation combines, and has tentatively formed China's commercial satellite application system.For the remote sensing demand of these resources, environment and seasat, be badly in need of obtaining more accurate atmospheric parameter, as gasoloid and cloud form condition, be used for carrying out accurate atmospheric correction to increase substantially its using value.And gasoloid and cloud be one of key constraints of current research whole world change and climate change to the uncertainty of radiation effect, gasoloid, cloud and Reflectivity for Growing Season are the key factors that affects the surface energy radiation balance.In addition, the cloud phase is the key factor that affects carrier rocket flight, missile flight and Flight Safety.Therefore grasp the global atmosphere gasoloid and the cloud distribution situation is vital to aviation, military affairs and space science research work.

Atmospheric sounding medium cloud and the most effective means of gasoloid are exactly Polarization Detection, and many spaceborne multi-angle polarized reflectance spectrum instrument such as existing POLDER, APS are succeeded in developing at present.These loading researchs are not difficult to find, the Polarization Modulation mode of its utilization mainly contains two kinds, i.e. time modulation and spatial modulation.

POLDER has adopted the mode of time-modulation, and time-modulation obtains polarization information and spectral information by rotating wave plate and optical filter runner.The advantage of this mode is: modulation principle is simple.Shortcoming is: wave plate is only for a certain specific wavelength, and therefore surveying multi-wavelength will increase multiplexed elements, the volume heaviness of system; And moving component arranged in system, vibration resistance, stability, reliability are poor; Once can only measure a polarization state, need the rotation wave plate repeatedly to measure and could obtain needed polarization information, so can not measure in real time.

APS has adopted the mode of spatial modulation, and spatial modulation is divided into multi beam by polarization beam apparatus by incident light, and every bundle light is respectively by obtaining required polarization state after the modulation of the polarization elements such as wave plate.The advantage of spatial modulation is: machinery-free rotates can measure full Stocks parameter I, Q, U, V in real time.Shortcoming is: optical path adjusting is very difficult, is difficult to guarantee that light beam does not change by the system polarization state; And need general four of a plurality of CCD() measure simultaneously, be difficult to guarantee homogeneity and synchronism; In addition multi-wavelength is surveyed and needed optical filter (increase the light path number or sacrifice real-time), the data precision of acquisition is also not high enough, and system is very heavy.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide that a kind of volume is little, lightweight, movement-less part, modulation is simple, demodulation accuracy is high and can obtain the Polarization Modulation device of spectral information and polarization information simultaneously.

Technical solution of the present invention is: a kind of light polarization modulator of movement-less part comprises achromatic quarter wave plate, hot multistage phase delay device, the polarization beam apparatus of nothing; The described multistage phase delay device without heat comprises sapphire crystal and MgF ₂crystal, sapphire crystal is positioned at the side near achromatic quarter wave plate, MgF ₂crystal is positioned at the side near polarization beam apparatus, sapphire crystal and MgF ₂the Thickness Ratio of crystal is 1:(2～3), the quick shaft direction of sapphire crystal and MgF ₂vertical and the angle two quick shaft directions and horizontal direction of the quick shaft direction of crystal is 45 °; The quick shaft direction of described achromatism quarter wave plate is vertical with horizontal direction, and the quick shaft direction of polarization beam apparatus is parallel or vertical with the quick shaft direction of achromatic quarter wave plate.

Described achromatic quarter wave plate is Fresnel rhombus.Described polarization beam apparatus is the Wollaston prism.Described sapphire crystal and MgF ₂the Thickness Ratio of crystal is 1:2.4.

The present invention's advantage compared with prior art is:

(1) after light polarization modulator of the present invention carries out spectral modulation to incident light, can access on detector that amplitude that the linear polarization degree changes and sinusoidal curve that phase place changes along with the linear polarization angle, through can directly obtaining spectral information and the polarization information of target after demodulation;

(2) light polarization modulator of the present invention is compared with the existing spatial modulation polarimetry mode based on path-splitting and minute amplitude mode, has little, the lightweight advantage of volume;

(3) light polarization modulator of the present invention is compared with the existing time-modulation polarimetry mode based on rotatory polarization sheet and electrooptical modulation, has the advantages such as real-time is good, movement-less part, good stability;

(4) Polarization Modulation mode of the present invention is owing to through the algorithm demodulation, can directly obtaining required linear polarization degree and linear polarization angle, rather than the image space modulating polarization measures after recording like that Stocks tetra-parameter I, Q, U, V and calculates degree of polarization and polarization angle again, so the demodulation method of spectral modulation is simple, demodulation accuracy is high, fast operation;

(5) light polarization modulator of the present invention has been coded in the spectrum dimension to the polarization information along with wavelength variations by spectral modulation, reduced the time (for example, while obtaining the different polarization angle information with rotating filtering sheet and polaroid, when different time is measured, the polarization information of target may change) or space (as the spatial modulation of minute amplitude, the optical element transmitance of different light paths is inconsistent, affects the precision of result) inconsistency on the impact of measurement result.

The accompanying drawing explanation

The theory of constitution block diagram that Fig. 1 is light polarization modulator of the present invention;

The element quick shaft direction schematic diagram that Fig. 2 is light polarization modulator of the present invention;

Fig. 3 is for adopting the normalized s obtained after spectral modulation of the present invention, the intensity map of p component;

Fig. 4 is for adopting true degree of polarization and the polarization angle image of the simulation polarization signal obtained after spectral modulation of the present invention.

Embodiment

As shown in Figure 1, the present invention mainly is comprised of multistage phase delay device and the polarization beam apparatus of achromatic quarter wave plate, nothing heat for the modulator of spectral modulation.

Achromatic quarter wave plate has been selected Fresnel rhombus, and its phase-delay quantity of the Fresnel rhombus based on total internal reflection principle is only relevant with refractive index, and its quick shaft direction is vertical with horizontal direction.In addition, achromatic quarter wave plate can also be selected Fresnel rhombus, solemn Buddhist nun's rhombohedreon, AD-1 type achromatic phase retarder, AD-2 type achromatic phase retarder, rhombohedreon phase delay device, rectangular build phase delay device, trapezoidal phase delay device etc.Specifically can be with reference to Li Guoliang, Song Lianke, Fan Kaimin. the optimal design of high precision rhomb-type achromatism retarder [J]. laser technology, 2011,35 (2) or Li Guoliang. the optimal design of high-performance achromatic phase retarders [D] .2007.

The multistage phase delay device of nothing heat is by sapphire and MgF ₂crystal composition, become respectively with the quick shaft direction of the quarter wave plate ± 45 ° of arrangements of the quick shaft direction of two crystal.The quick shaft direction of quarter wave plate is parallel with the light transmission shaft direction of polaroid, can be 0 ° or 90 °.Because the phase-delay quantity of wave plate is subject to the impact of temperature very large, especially multistage wave plate, so two kinds of crystal will select suitable Thickness Ratio to eliminate the dependence of total phase-delay quantity to temperature.Sapphire described here and MgF ₂thickness Ratio be 1:(2～3).

In order to design the multistage phase delay device without thermalization, need to find two kinds of materials that thermo-optical constant is different, make for the residual temperature dependence of the retardation after a certain definite thickness ratio combination minimum in desired visible wavelength range.Two wave plate j=1,2, thickness d _j, birefraction n _e,j-n _o,j, the optical path difference of combination can be provided by following formula:

δ(λ,T)=δ ₁(λ,T)±δ ₂(λ,T)=|n _e,1(λ,T)-n _o,1(λ,T)|d ₁±|n _e,2(λ,T)-n _o,2(λ,T)|d ₂

" ± ": mean increase or the minimizing of interwoven crystal number, the absolute value of having got birefraction in formula is corresponding angle rather than the optical axis between the fast axle in order to describe wave plate.Desiredly without thermal property, can be provided by following formula:

γ ₁·δ ₁(λ ₀)±γ ₂·δ ₂(λ ₀)=0

γ _jthe thermo-optical constant of crystal, wherein:

${\mathrm{\γ}}_j=\frac{1}{{\mathrm{\δ}}_j\left({\mathrm{\λ}}_0\right)}\·\frac{d{\mathrm{\δ}}_j\left({\mathrm{\λ}}_0\right)}{\mathrm{dT}}=\frac{1}{d_j}\·\frac{{\mathrm{dd}}_j}{\mathrm{dT}}+\frac{1}{n_{e,j}\left({\mathrm{\λ}}_0\right)-n_{o,j}\left({\mathrm{\λ}}_0\right)}\·\frac{d(n_{e,j}\left({\mathrm{\λ}}_0\right)-n_{o,j}\left({\mathrm{\λ}}_0)\right)}{\mathrm{dT}}$

With above-mentioned formula, calculate: can access Thickness Ratio 1:2～1:3.

The γ of most common crystal _jvalue is all born, and therefore must select "-" crystal to combine to construct the multistage phase delay device without heat.

The FOV performance of combination wave plate depends on n _{e, 1}-n _{o, 1}and n _{e, 2}-n _{o, 2}symbol.The birefraction of supposing first wave plate is on the occasion of (quartz or MgF ₂).By consulting the γ of associated materials _jvalue, found the crystal combination wave plate that can produce in the 350nm-800nm wavelength coverage without thermalization.Sapphire and MgF have been selected ₂as the combination of the crystal without hot, its optimal thickness ratio is 1:2.4.

From, sapphire Al ₂o ₃in the 0.22-5.0um wavelength coverage, the refractive index of its o light and e light can be drawn by following formula:

$n_o^2=1+\frac{{1.43134936\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.0726631\right)}^2]}+\frac{0.65054713{\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.1193242\right)}^2]}+\frac{{5.3414021\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(18.028251\right)}^2]}$

$n_e^2=1+\frac{{1.5039759\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.0740288\right)}^2]}+\frac{{0.55069141\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.1216529\right)}^2]}+\frac{{6.59273791\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(20.072248\right)}^2]}$

MgF ₂in 0.4-3.1um wavelength wavelength coverage, the refractive index of its o light and e light can be drawn by following formula:

$n_o^2=1+\frac{{0.48755108\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.04338408\right)}^2]}+\frac{0.39875031{\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.09461442\right)}^2]}+\frac{{2.3120353\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(23.793604\right)}^2]}$

$n_e^2=1+\frac{{0.41344023\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.03684262\right)}^2]}+\frac{{0.50497499\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(0.09076162\right)}^2]}+\frac{{2.4904862\mathrm{\λ}}^2}{[{\mathrm{\λ}}^2-{\left(12.771995\right)}^2]}$

Can be obtained the δ of spectral modulation by above-mentioned formula, i.e. optical path difference.

Above content specifically can be referring to S.Guimond, and D.Elmore, ' Designing effective crystal waveplates requires understanding the engineering tradeoffs ', OE magazine May (2004).

Polarization beam apparatus is selected the Wollaston prism, because polarization beam apparatus not only will have large extinction ratio also large wavelength coverage will be arranged, the Wollaston prism can be good at meeting the demands.In addition, polarization beam apparatus can also be selected: the polarization beam splitters such as Nicol prism, Glan prism, savart plate.Specifically can be with reference to the pure people of Electronic Industry Press 2008.4, " physical optics " beam select court of a feudal ruler or " interference imaging spectral technology " Science Press 2010.1.

As shown in Figure 2, the polarized light of target enters light polarization modulator of the present invention by left side, supposes that the Stokes of incident light is:

S _in＝(S ₀(σ)?S ₁(σ)?S ₂(σ)?S ₃(σ)) ^T

The Muller matrix of Fresnel rib body is:

$M_{\mathrm{Fresnel}}=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 0& -1\\ 0& 0& 1& 0\end{array}\right)$

The phase delay of phase delay device is φ (σ), quick shaft direction angle θ, and σ is wave number, Muller matrix is:

$M=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& {\cos }^{2}2\mathrm{\θ}+{\sin }^{2}2\mathrm{\θ}\cos \mathrm{\φ}\left(\mathrm{\σ}\right)& \sin 2\mathrm{\θ}\cos 2\mathrm{\θ}(1-\cos \mathrm{\φ}\left(\mathrm{\σ}\right))& -\sin 2\mathrm{\θ}\sin \mathrm{\φ}\left(\mathrm{\σ}\right)\\ 0& \sin 2\mathrm{\θ}\cos 2\mathrm{\θ}(1-\cos \mathrm{\φ}\left(\mathrm{\σ}\right))& {\sin }^{2}2\mathrm{\θ}+{\cos }^{2}2\mathrm{\θ}\cos \mathrm{\φ}\left(\mathrm{\σ}\right)& \cos 2\mathrm{\θ}\sin \mathrm{\φ}\left(\mathrm{\σ}\right)\\ 0& \sin 2\mathrm{\θ}\sin \mathrm{\φ}\left(\mathrm{\σ}\right)& -\cos 2\mathrm{\θ}\sin \mathrm{\φ}\left(\mathrm{\σ}\right)& \cos \mathrm{\φ}\left(\mathrm{\σ}\right)\end{array}\right)$

Therefore, sapphire fast shaft angle degree is 45 °, and phase delay is φ ₁(σ), MgF ₂fast shaft angle degree be-45 °, phase delay is φ ₂(σ), its Muller matrix is respectively:

$M_{\mathrm{sapphire}}=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& \cos {\mathrm{\φ}}_1\left(\mathrm{\σ}\right)& 0& -\sin {\mathrm{\φ}}_1\left(\mathrm{\σ}\right)\\ 0& 0& 1& 0\\ 0& \sin {\mathrm{\φ}}_1\left(\mathrm{\σ}\right)& 0& \cos {\mathrm{\φ}}_1\left(\mathrm{\σ}\right)\end{array}\right),M_{\mathrm{Mg}{F}_2}=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& \cos {\mathrm{\φ}}_2\left(\mathrm{\σ}\right)& 0& \sin {\mathrm{\φ}}_2\left(\mathrm{\σ}\right)\\ 0& 0& 1& 0\\ 0& -\sin {\mathrm{\φ}}_2\left(\mathrm{\σ}\right)& 0& \cos {\mathrm{\φ}}_2\left(\mathrm{\σ}\right)\end{array}\right)$

The Muller matrix of Wollaston prism is:

$M_{\mathrm{wollaston}}=\frac{1}{2}\left(\begin{array}{cccc}1& -1& 0& 0\\ -1& 1& 0& 0\\ 0& 0& 0& 0\\ 0& 0& 0& 0\end{array}\right)$

The Stokes of emergent light is:

$S_{\mathrm{out}}=M_{\mathrm{wollaston}}{M}_{\mathrm{sapphire}}{M}_{\mathrm{Mg}{F}_2}{M}_{\mathrm{fresnel}}{S}_{\mathrm{in}}$

$\left(\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="S"\; filenames="HDA0000386401620000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_0^{\&prime;}\left(\mathrm{\&sigma;}\right)\\ {\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HDA0000386401620000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_1^{\&prime;}\left(\mathrm{\&sigma;}\right)\\ S_2^{\&prime;}\left(\mathrm{\&sigma;}\right)\\ S_3^{\&prime;}\left(\mathrm{\&sigma;}\right)\end{array}\right)=\frac{1}{2}\left(\begin{array}{cccc}1& -1& 0& 0\\ -1& 1& 0& 0\\ 0& 0& 0& 0\\ 0& 0& 0& 0\end{array}\right)\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& {\cos \mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)& 0& {\sin \mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\\ 0& 0& 1& 0\\ 0& -\sin {\mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)& 0& \cos {\mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\end{array}\right)\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& {\cos \mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)& 0& -\sin {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)\\ 0& 0& 1& 0\\ 0& {\sin \mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)& 0& \cos {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)\end{array}\right)\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 0& -1\\ 0& 0& 1& 0\end{array}\right)\left(\begin{array}{c}{S}_0\left(\mathrm{\&sigma;}\right)\\ S_1\left(\mathrm{\&sigma;}\right)\\ S_2\left(\mathrm{\&sigma;}\right)\\ S_3\left(\mathrm{\&sigma;}\right)\end{array}\right)$

The Stokes vector element spectrum matrix that the equal sign left side is the spectral modulation emergent light, equal sign the right is respectively Wollaston prism, MgF from left to right ₂the Muller matrix of crystal, sapphire (Sapphire) crystal, Fresnel rhombus and the Stokes vector element spectrum matrix of incident light.Mean S ' with P (σ) ₀(σ), the i.e. output power spectrum of emergent light:

$P\left(\mathrm{\&sigma;}\right)=\frac{1}{2}\{S_0\left(\mathrm{\&sigma;}\right)-S_1\left(\mathrm{\&sigma;}\right)[\cos {\mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\cos {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)+{\sin \mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\sin {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)]+S_2\left(\mathrm{\&sigma;}\right)[\cos {\mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\sin {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)-{\sin \mathrm{\&phi;}}_2\left(\mathrm{\&sigma;}\right)\cos {\mathrm{\&phi;}}_1\left(\mathrm{\&sigma;}\right)\left]\right\}$

Due to $P_L=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HDA0000386401620000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_1^2+S_2^2}}{{\mathrm{<figure-callout\; id="0"\; label="S"\; filenames="HDA0000386401620000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_0},{\mathrm{\&phi;}}_L=\frac{1}{2}\arctan \frac{S_3}{S_2},$ P wherein _land φ _lmean respectively linear polarization degree and linear polarization angle, the substitution output power spectrum also can obtain its conversion:

$P\left(\mathrm{\&sigma;}\right)={\mathrm{<figure-callout\; id="0"\; label="S"\; filenames="HDA0000386401620000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_0^{\&prime;}\left(\mathrm{\&lambda;}\right)=\frac{1}{2}{S}_0\left(\mathrm{\&lambda;}\right)\{1-P_L\left(\mathrm{\&lambda;}\right)\cos [\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}\mathrm{\&delta;}(\mathrm{\&lambda;},T)+2{\mathrm{\&phi;}}_L\left(\mathrm{\&lambda;}\right)\left]\right\}$

In above formula, σ means wave number, and λ means wavelength, and δ means the optical path difference that spectral modulation produces, S ₀(λ) mean the light intensity of the polarized light of target, S ' ₀(λ) mean to obtain the polarized light light intensity after spectral modulation.

Can obtain linear polarization degree and the linear polarization angle of target different wave length by demodulating algorithm to the above formula demodulation.Because polarization information directly has been stored in the spectrum dimension, the polarization information obtained is with the wavelength continually varying, has also obtained hyperspectral information when obtaining polarization information.

Fig. 3 is the normalized s obtained after simulated spectra modulation Wollaston prismatic decomposition by the principle of the invention, the intensity map of p component.The linearly polarized light of incident is after the Wollaston prism of spectral modulation module, and being modulated into is the mutually perpendicular S ripple of direction of vibration and the P ripple of the two bundles out-phase that is sinusoidal variation.Because two bundle polarized light out-phase, thus a branch of polarized light when crest, a branch of polarized light is in trough in addition.The intensity of two modulating polarization light beams and the total light intensity that equals incident polarized light.

Fig. 4 is degree of polarization and the polarization angle image of the simulation polarization signal that obtains through simulating inversion method by principle of the present invention.The principle of the spectral modulation proposed according to the present invention is carried out simulation analysis, and demodulation has been carried out in linear polarization degree and the linear polarization angle of simulated target.Fig. 4 (a) wherein, Fig. 4 (b) is respectively linear polarization degree and the linear polarization angle that demodulation obtains to target information.Known through emulation, the polarization information curve obtained and inputted consistent conforming to of parameter.

The content be not described in detail in instructions of the present invention belongs to those skilled in the art's known technology.

Claims (4)

1. the light polarization modulator of a movement-less part, is characterized in that: the multistage phase delay device, the polarization beam apparatus that comprise achromatic quarter wave plate, nothing heat; The described multistage phase delay device without heat comprises sapphire crystal and MgF ₂crystal, sapphire crystal is positioned at the side near achromatic quarter wave plate, MgF ₂crystal is positioned at the side near polarization beam apparatus, sapphire crystal and MgF ₂the Thickness Ratio of crystal is 1:(2～3), the quick shaft direction of sapphire crystal and MgF ₂vertical and the angle two quick shaft directions and horizontal direction of the quick shaft direction of crystal is 45 °; The quick shaft direction of described achromatism quarter wave plate is vertical with horizontal direction, and the quick shaft direction of polarization beam apparatus is parallel or vertical with the quick shaft direction of achromatic quarter wave plate.

2. the light polarization modulator of a kind of movement-less part according to claim 1, it is characterized in that: described achromatic quarter wave plate is Fresnel rhombus.

3. the light polarization modulator of a kind of movement-less part according to claim 1, it is characterized in that: described polarization beam apparatus is the Wollaston prism.

4. the light polarization modulator of a kind of movement-less part according to claim 1, is characterized in that: described sapphire crystal and MgF ₂the Thickness Ratio of crystal is 1:2.4.

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