CN103487945B - A kind of Efficient polarization purification devices - Google Patents

Abstract

The invention provides a kind of efficient polarization purification devices, be made up of wave-plate stack, quarter-wave plate, catoptron.Wave-plate stack slant setting, its surface normal from the horizontal by Brewster angle, the directional light that laser instrument is sent with brewster angle incidence wave-plate stack, reflect s-polarized light, transmitting P-type polarisation light.Place a quarter-wave plate in S reflected light direction, make reflect s-polarized light vertical irradiation quarter-wave plate, optical axis is from the horizontal by 45 °.After quarter-wave plate, place a catoptron, S polarized light converts P polarized light to after quarter-wave plate and catoptron, with brewster angle incidence wave-plate stack.Edge's placement one in the emergent light direction of reflected light after wave-plate stack, perpendicular to the catoptron of wave-plate stack, makes its emergent light just in time along horizontal direction.The present invention utilizes few element, obtains the one direction linearly polarized light of high-polarization, high polarization purity, high-energy utilization factor.

Description

A kind of Efficient polarization purification devices

Technical field

The present invention relates to the technical field of polarization converter, be specifically related to a kind of Efficient polarization purification devices, it is the polarization converter of high-polarization, high polarization purity, high conversion efficiency.

Background technology

Wave-plate stack is superimposed by one group of parallel plane glass sheet and forms, when wave-plate stack surface normal and horizontal direction form Brewster angle, when natural light glancing incidence is also by wave-plate stack, through the refract light continuously and refraction incident with identical state of wave-plate stack, per pass interface, from refract light, all reflect away the component (S component) of a part perpendicular to paper vibration, finally make by the transmitted light of the wave-plate stack linearly polarized light (P component) close to the parallel plane of incidence.The light component of parallel plane of incidence vibration does not have reflection loss by during wave-plate stack, and the light component of vertical paper vibration by produce up to 15% reflection loss and energy of reflection light be not utilized, the transmitted light energy resulting through wave-plate stack later is lower, and if obtain high-polarization just must increase wave plate number, cause cost higher.

Summary of the invention

The present invention is directed to the deficiencies in the prior art and defect, a kind of device comprising a tilted-putted wave-plate stack, a quarter-wave plate and two catoptrons is provided, makes full use of reflected light to improve total degree of polarization and capacity usage ratio.

The technical solution used in the present invention is: a kind of Efficient polarization purification devices, described purification devices is made up of wave-plate stack, quarter-wave plate, the first catoptron and the second catoptron, wave-plate stack surface normal direction is from the horizontal by Brewster angle, quarter-wave plate and the first catoptron vertical reflection light direction are placed, reflect s-polarized light is successively through quarter-wave plate, the first catoptron and quarter-wave plate, convert S polarized light to P polarized light, in the edge in the transmitted light direction of reflected light after wave-plate stack, vertical wave-plate stack places the second catoptron.

Wherein, the position of quarter-wave plate and the first catoptron according to debuging needs, can move in parallel at vertical reflection light direction.

Wherein, quarter-wave plate is equal with the size AH of the first mirror size JK, the second catoptron and be all more than or equal to beam diameter D, i.e. JK=AH >=D.

Wherein, what wave-plate stack adopted is fused quartz, or adopts CaF ₂, MgF ₂, K9 ultraviolet can be saturating optical material.

Wherein, each size determines relation: l and θ, d, D are relevant, and namely the length L of wave-plate stack is by wave-plate stack material n ₂, wave-plate stack gross thickness d and beam diameter D determines, required wave plate number N can be determined according to the specific requirement of degree of polarization, the thickness of each block wave plate can be determined by wave-plate stack gross thickness d and wave plate number N

Principle of the present invention is:

Wave-plate stack surface normal from the horizontal by Brewster angle, during directional light incident wave sheet pile, reflect s-polarized light, transmitting P-type polarisation light.Quarter-wave plate is placed perpendicular to S reflected light direction, and make S polarized light vertical irradiation quarter-wave plate, S polarized light becomes right-circularly polarized light through quarter-wave plate.A catoptron placed by parallel quarter-wave plate, and the right-circularly polarized light after quarter-wave plate is reflected into left circularly polarized light, and this left circularly polarized light passes perpendicularly through quarter-wave plate and becomes P polarized light.S polarized light converts P polarized light to after quarter-wave plate and catoptron, along former reflection direction with brewster angle incidence wave-plate stack.Edge's placement one in the transmitted light direction of reflected light after wave-plate stack is perpendicular to the catoptron of wave-plate stack, and the light after reflection is just in time along horizontal direction.Whole device is simply easy to realize, and conversion efficiency is high.

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

1) polarization purification devices of the present invention only utilizes four elements, and the absorption loss in process is little, obtains the one direction linearly polarized light of high-polarization, high polarization purity, high-energy utilization factor.

2) polarization purification devices of the present invention not only can be applied to the polarization purifying in polarized illumination system, also may be used in external cavity type gas laser.

3) polarization purification devices of the present invention not only effectively make use of the energy of reflected light, and ingeniously makes it through wave-plate stack, reaches energy and strengthens effect.

Accompanying drawing explanation

Fig. 1 is the main structure figure of efficient polarization purification devices;

Fig. 2 is the schematic diagram that S polarized light converts P polarized light to;

Fig. 3 is the catadioptric schematic diagram of light in wave-plate stack inside;

Fig. 4 is that transmitted light degree of polarization, total reflected light degree of polarization and total degree of polarization are with wave plate number change curve;

Fig. 5 determines that the marginal ray of concrete component size, beam diameter and wave plate thickness propagates schematic diagram.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.

Fig. 1 is the main structure figure of efficient polarization purification devices.Be made up of wave-plate stack 1, quarter-wave plate 2, first catoptron 3 and the second catoptron 4.θ in figure _brepresent Brewster angle, different materials has different Brewster angles.For 193nm wave band in the present embodiment, wave-plate stack 1 adopts to the good fused quartz of uv transmittance as material, and refractive index is 1.560321, so Brewster angle is 57.344 °, wave-plate stack 1 surface normal is from the horizontal by 57.344 °.For CaF ₂, MgF ₂, material that other ultraviolet such as K9 can be saturating or the respective material (the common quartz glass as visible light wave range) for its all band, the principle of this device is applicable equally.This tilted-putted wave-plate stack 1, S polarized light of natural light glancing incidence is reflected, P polarized light transmission.In order to make full use of by the energy of the S polarized light reflected, the S polarized light added in reflected light direction as shown in Figure 2 converts the device of P polarized light to, is made up of quarter-wave plate 2 and the first catoptron 3.All reflected light of wave-plate stack 1 are the S polarized light of vertical paper vibration, namely along the x-axis direction vibration of the coordinate system of definition, and its vertical incidence quarter-wave plate 2, the optical axis of quarter-wave plate 2 and x-axis angle at 45 °.Because direction of vibration and optical axis linearly polarized light at 45 ° produce the circularly polarized light of a certain rotation direction through quarter-wave sector-meeting, and the circularly polarized light of a certain rotation direction produces the linearly polarized light at 45 ° with optical axis through quarter-wave plate, so can utilize quarter-wave plate and arrangement of mirrors that the direction of vibration half-twist of S polarized light is become P polarized light, so S polarized light produces right-circularly polarized light 5 through quarter-wave plate 2, become left circularly polarized light 6 through the first catoptron 3, left circularly polarized light 6 becomes P polarized light through quarter-wave plate 2.The S polarized light of all reflections converts P polarized light to, with brewster angle incidence wave-plate stack 1 after quarter-wave plate 2 and the first catoptron 3.In addition, the position of quarter-wave plate 2 and the first catoptron 3 according to debuging needs, can move in parallel at vertical reflection light direction.A end margin placement one after wave-plate stack 1, perpendicular to the second catoptron 4 of wave-plate stack 1, is easy to draw from Fig. 1 intermediate cam shape relation, after the second catoptron 4 reflects, and the outgoing in the horizontal direction of P polarized light.

By angular relationship in Fig. 1, ∠ α=θ _b, incident ray i becomes Brewster angle θ with wave-plate stack 1 normal _bglancing incidence, after wave-plate stack 1, emergent ray is parallel with incident ray (becomes θ with wave-plate stack 1 normal direction _b), because reflected light is same with θ after quarter-wave plate 2 and the first catoptron 3 _bincident wave sheet pile 1, so the emergent ray of reflected light after wave-plate stack 1 becomes θ with wave-plate stack 1 normal direction _b, from angular relationship in figure: ∠ β=θ _b, ∠ γ=90 °-θ _b, then

∠ α+∠ β+2 ∠ γ=θ _b+ θ _b+ 2 (90 ° of-θ _b)=180 °, the light i ' namely after the second catoptron 4 is parallel to incident ray i, so be horizontal direction outgoing.

Fig. 3 is the catadioptric figure of light in sheet pile inside, for the purpose of simple, only consider the reflection between wave plate, does not consider the reflection of wave plate inside.N ₁for the refractive index of air, n ₂for the refractive index of wave plate.V is the Stokes vector of incidence natural lights, with V _rNand V _tNrepresent the Stokes vector of N article of reflected light and transmitted light respectively, for the catadioptric situation of three light in figure, depict inner catadioptric schematic diagram, by that analogy, the catadioptric figure of N bar light can be obtained.N in Fig. 3 ₁layer does not represent real air layer thickness, only draws the propagation condition of wherein light for convenience.

First we derive transmission and the reflection Muller matrix of wave-plate stack 1, and then the degree of polarization of derivation natural light total reflected light after wave-plate stack 1, and the degree of polarization of transmitted light and the degree of polarization of all reflected light after wave-plate stack 1, finally obtain total degree of polarization.And by MATLAB program calculation, can obtain each degree of polarization result corresponding to the different wave plate numbers shown in table 1, we only give the degree of polarization result of 1 ~ 20 block of wave plate, and total degree of polarization of 20 blocks of wave plates is very high, and degree of polarization is afterwards tending towards 100%.For the purpose of directly perceived, Zong draw the degree of polarization of all reflected light, the degree of polarization of transmitted light and the degree of polarization as shown in Figure 4 change curve with wave plate number.

The each degree of polarization numerical result of table 1

The total degree of polarization of sheet number (block) total reflected light degree of polarization transmitted light degree of polarization
	171.88%20.19%49.36%
282.05%38.79%65.98%
	387.99%54.70%76.45%
491.91%67.44%83.78%
	594.56%77.13%88.94%
696.35%84.20%92.52%
	797.56%89.22%94.97%
898.38%92.71%96.63%
	998.92%95.10%97.75%
1099.28%96.72%98.50%
	1199.52%97.81%99.00%
1299.68%98.54%99.34%
	1399.79%99.03%99.56%
1498.86%99.35%99.71%
	1599.91%99.57%99.80%
1699.94%99.71%99.87%
	1799.96%99.81%99.91%
1899.97%99.87%99.94%

19	99.98%	99.92%	99.96%
				20	99.99%	99.94%	99.97%

The mathematical derivation process of total degree of polarization:

The transmission Muller matrix of one block of wave plate and the degree of polarization through N block wave plate transmitted light:

The Muller matrix M of wave plate two interface ₁, M ₂for:

$M_1=\frac{{2n}_2}{n_1}{\left(\frac{\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2}{\sin \mathrm{\β}\cos \mathrm{\α}}\right)}^2\left(\begin{array}{cccc}{\cos }^2\mathrm{\α}+1& {\cos }^2\mathrm{\α}-1& 0& 0\\ {\cos }^2\mathrm{\α}-1& {\cos }^2\mathrm{\α}+1& 0& 0\\ 0& 0& 2\cos \mathrm{\α}& 0\\ 0& 0& 0& 2\cos \mathrm{\α}\end{array}\right),\mathrm{\α}={\mathrm{\θ}}_1-{\mathrm{\θ}}_2,\mathrm{\β}={\mathrm{\θ}}_1+{\mathrm{\θ}}_2$

$M_2=\frac{{2n}_1}{n_2}{\left(\frac{\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2}{\sin \mathrm{\β}\cos \mathrm{\α}}\right)}^2\left(\begin{array}{cccc}{\cos }^2\mathrm{\α}+1& {\cos }^2\mathrm{\α}-1& 0& 0\\ {\cos }^2\mathrm{\α}-1& {\cos }^2\mathrm{\α}+1& 0& 0\\ 0& 0& 2\cos \mathrm{\α}& 0\\ 0& 0& 0& 2\cos \mathrm{\α}\end{array}\right)$

Wherein θ ₁and θ ₂represent incident angle and refraction angle respectively.

The then transmission Muller matrix M of one block of wave plate _tfor:

$M_t=M_2\·M_1=\frac{1}{2}{\left(\frac{\cos {2\mathrm{\θ}}_1\sin {2\mathrm{\θ}}_2}{{\sin }^2\mathrm{\β}\mathrm{co}{s}^2\mathrm{\α}}\right)}^2\left(\begin{array}{cccc}{\cos }^4\mathrm{\α}+1& {\cos }^4\mathrm{\α}-1& 0& 0\\ {\cos }^4\mathrm{\α}-1& {\cos }^4\mathrm{\α}+1& 0& 0\\ 0& 0& 2\mathrm{co}{s}^2\mathrm{\α}& 0\\ 0& 0& 0& 2\mathrm{co}{s}^2\mathrm{\α}\end{array}\right)$

And then obtain N block wave plate transmission Muller matrix M ⁿ _tfor:

${M^N}_t=M_t...M_t=A^N\left(\begin{array}{cccc}{\cos }^{4N}\mathrm{\α}+1& {\cos }^{4N}\mathrm{\α}-1& 0& 0\\ {\cos }^{4N}\mathrm{\α}-1& {\cos }^{4N}\mathrm{\α}+1& 0& 0\\ 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^N& 0\\ 0& 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^N\end{array}\right)$

Wherein $A=\frac{1}{2}{\left(\frac{\sin 2{\mathrm{\θ}}_1\sin 2{\mathrm{\θ}}_2}{{\sin }^2\mathrm{\β}{\cos }^2\mathrm{\α}}\right)}^2$

The transmitted light Stokes vector V of natural light after N block glass sheet _tNfor:

$\begin{array}{c}{V}_{\mathrm{tN}}={M_t}^N*V\\ =A^N\left(\begin{array}{cccc}{\cos }^{4N}\mathrm{\α}+1& {\cos }^{4N}\mathrm{\α}-1& 0& 0\\ {\cos }^{4N}\mathrm{\α}-1& {\cos }^{4N}\mathrm{\α}+1& 0& 0\\ 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^N& 0\\ 0& 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^N\end{array}\right)\\ =A^N\left(\begin{array}{c}{\cos }^{4N}\mathrm{\α}+1\\ {\cos }^{4N}\mathrm{\α}-1\\ 0\\ 0\end{array}\right)=\left(\begin{array}{c}{S}_0\\ S_1\\ S_2\\ S_3\end{array}\right)\end{array}\left(\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right)$

The then degree of polarization of transmitted light: $P=\frac{\sqrt{{S_1}^2+{S_2}^2+{S_3}^2}}{S_0}=\frac{1-{\cos }^{4N}\mathrm{\α}}{1+{\cos }^{4N}\mathrm{\α}},(\mathrm{\α}={\mathrm{\θ}}_1-{\mathrm{\θ}}_2)$

Wherein s ₀, s ₁, s ₂and s ₃represent four components of Stokes vector.

Degree of polarization with transmitted light during brewster angle incidence:

$P=\frac{\sqrt{{S_1}^2+{S_2}^2+{S_3}^2}}{S_0}=\frac{1-{\cos }^{4N}2{\mathrm{\θ}}_1}{1+{\cos }^{4N}2{\mathrm{\θ}}_1}$

The reflection Muller matrix of one block of wave plate is derived:

Fresnel formula:

$\left\{\begin{array}{c}{r}_s=-\frac{\sin ({\mathrm{\θ}}_1-{\mathrm{\θ}}_2)}{\sin ({\mathrm{\θ}}_1+{\mathrm{\θ}}_2)}=\frac{n_1\cos {\mathrm{\θ}}_1-n_2\cos {\mathrm{\θ}}_2}{n_1\cos {\mathrm{\θ}}_1+n_2\cos {\mathrm{\θ}}_2}\\ r_p=\frac{\tan (\mathrm{\θ}1-{\mathrm{\θ}}_2)}{\tan ({\mathrm{\θ}}_1+{\mathrm{\θ}}_2)}=\frac{n_2\cos {\mathrm{\θ}}_1-n_1\cos {\mathrm{\θ}}_2}{n_2\cos {\mathrm{\θ}}_1+n_1\cos {\mathrm{\θ}}_2}\\ t_s=\frac{2\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2}{\sin ({\mathrm{\θ}}_1+{\mathrm{\θ}}_2)}=\frac{{2n}_1\cos {\mathrm{\θ}}_1}{n_1\cos {\mathrm{\θ}}_1+n_2\cos {\mathrm{\θ}}_2}\\ t_p=\frac{2\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2}{\sin ({\mathrm{\θ}}_1+{\mathrm{\θ}}_2)\cos ({\mathrm{\θ}}_1-{\mathrm{\θ}}_2)}=\frac{{2n}_1\cos {\mathrm{\θ}}_1}{n_2\cos {\mathrm{\θ}}_1+n_1\cos {\mathrm{\θ}}_2}\end{array}\right.$

The Stokes vector of incident light and reflected light is expressed as:

$\left\{\begin{array}{c}I=E_S{E^{*}}_S+E_p{E^{*}}_p\\ M=E_S{E^{*}}_S-E_p{E^{*}}_p\\ C=E_S{E^{*}}_P+E_p{E^{*}}_S\\ S=E_S{E^{*}}_P-E_p{E^{*}}_S\end{array}\right.\left\{\begin{array}{c}{I}_r={r^2}_s{E}_S{E^{*}}_S+{r^2}_p{E}_p{E^{*}}_p\\ M_r={r^2}_s{E}_s{E^{*}}_S-{r^2}_p{E}_p{E^{*}}_p\\ C_r=r_S{r}_p(E_s{E^{*}}_P+E_p{E^{*}}_S)\\ S_r=r_s{r}_p(E_S{E^{*}}_P-E_P{E^{*}}_S)\end{array}\right.$

Then reflected light and incident light are connected by Muller matrix:

$\left(\begin{array}{c}{I}_r\\ M_r\\ C_r\\ S_r\end{array}\right)=\left(\begin{array}{cccc}{r^2}_s+{r^2}_p& {r^2}_s-{r^2}_p& 0& 0\\ {r^2}_s-{r^2}_p& {r^2}_s+{r^2}_p& 0& 0\\ 0& 0& {2r}_s{r}_p& 0\\ 0& 0& 0& {2r}_s{r}_p\end{array}\right)\left(\begin{array}{c}I\\ M\\ C\\ S\end{array}\right)$

Then the reflection Muller matrix of wave plate is Mr:

$M_r={r^2}_p\left(\begin{array}{cccc}1+{\mathrm{\ϵ}}^2& 1-{\mathrm{\ϵ}}^2& 0& 0\\ 1-{\mathrm{\ϵ}}^2& 1+{\mathrm{\ϵ}}^2& 0& 0\\ 0& 0& 2\mathrm{\ϵ}& 0\\ 0& 0& 0& 2\mathrm{\ϵ}\end{array}\right),\mathrm{\ϵ}=\frac{r_s}{r_p}$

The Stokes vector of the total reflected light of natural light after N sheet is derived:

As shown in Figure 3, do not consider the reflection in wave plate inside, only consider the reflection of light between wave plate, the Stokes vector through N block back reflection light can be obtained:

V _r1＝M _rV，V _r2＝M _tM _rM _tV，V _r3＝M _tM _tM _rM _tM _tV，......V _rN＝M _t ^(N-1)M _rM _t ^(N-1)V

Wherein V _rNrepresent the Stokes vector of N article of reflected light, N=1,2,3

The transmission Muller matrix of known N block wave plate, the Muller matrix M of (N-1) block that is easy to get ^n-1 _tfor:

${M^{N-1}}_t=A^{N-1}\left(\begin{array}{cccc}{\cos }^{4(N-1)}\mathrm{\α}+1& {\cos }^{4(N-1)}\mathrm{\α}-1& 0& 0\\ {\cos }^{4(N-1)}\mathrm{\α}-1& {\cos }^{4(N-1)}\mathrm{\α}+1& 0& 0\\ 0& 0& {\left(2\mathrm{co}{s}^2\mathrm{\α}\right)}^{(N-1)}& 0\\ 0& 0& 0& {\left(2\mathrm{co}{s}^2\mathrm{\α}\right)}^{(N-1)}\end{array}\right)$

The Stokes vector V of the reflected light then after N block _rNfor:

$\begin{array}{c}{V}_{\mathrm{rN}}={M_t}^{(N-1)}{M}_r{M_t}^{(N-1)}V\\ =A^{N-1}\left(\begin{array}{cccc}{\cos }^{4(N-1)}\mathrm{\α}-1& {\cos }^{4(N-1)}\mathrm{\α}-1& 0& 0\\ {\cos }^{4(N-1)}\mathrm{\α}-1& {\cos }^{4(N+1)}\mathrm{\α}+1& 0& 0\\ 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^{(N-1)}& 0\\ 0& 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^{(N-1)}\end{array}\right)\·\\ {r_p}^2\left(\begin{array}{cccc}1+{\mathrm{\ϵ}}^2& 1-{\mathrm{\ϵ}}^2& 0& 0\\ 1-{\mathrm{\ϵ}}^2& 1+{\mathrm{\ϵ}}^2& 0& 0\\ 0& 0& 2\mathrm{\ϵ}& 0\\ 0& 0& 0& 2\mathrm{\ϵ}\end{array}\right)\·\\ A^{N-1}\left(\begin{array}{cccc}{\cos }^{4(N-1)}\mathrm{\α}+1& {\cos }^{4(N-1)}\mathrm{\α}-1& 0& 0\\ {\cos }^{4(N-1)}\mathrm{\α}-1& {\cos }^{4(N-1)}\mathrm{\α}+1& 0& 0\\ 0& 0& {\left({2\cos }^2\right)}^{(N-1)}& 0\\ 0& 0& 0& {\left({2\cos }^2\mathrm{\α}\right)}^{(N-1)}\end{array}\right)\left(\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right)\end{array}$

The then Stokes vector V of total reflected light _rfor: $V_r=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{V}_{\mathrm{ri}}=V_{r1}+V_{r2}+...V_{\mathrm{rN}}$

Total reflected light again enters the transmitted light Stokes vector after wave-plate stack 1 through quarter-wave plate 2 and the first catoptron 3 and derives:

The Muller matrix M of the quarter-wave plate 2 that angle is 45 ° _{t (1/4)}(45 °) are: the Muller matrix M of the first catoptron 3 _r(-) is: $M_r(-)=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& -1& 0\\ 0& 0& 0& -1\end{array}\right)$

Total reflected light through quarter-wave plate 2, first catoptron 3, quarter-wave plate 2, enters the transmitted light Stokes vector V after sheet pile 1 successively again _rtn is: V _rtN=M _t ⁿm _{t (1/4}) M _r(-) M _{t (1/4}) _vr

Total Stokes vector:

Final total Stokes vector V _zong(not considering the reflection of last catoptron) is the Stokes vector V of total reflected light again by wave-plate stack 1 after conversion _rtNwith the Stokes vector V of transmitted light _tNsum, that is:

$\begin{array}{c}{V}_{\mathrm{zong}}=V_{\mathrm{rtN}}+V_{\mathrm{tN}}\\ ={M_t}^N{M}_{t(1/4)}{M}_r(-)M_{t(1/4)}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{V}_{\mathrm{ri}}+{M_t}^N*V\\ ={M_t}^N{M}_{t(1/4)}{M}_r(-)M_{t(1/4)}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\left({M_t}^{(i=1)}{M}_r{M_t}^{(i=1)}V\right)+{M_t}^N*V\end{array}$

By V _zonfour components of g substitute into formula: total degree of polarization can be calculated.

In Fig. 4,1 is the change curve of total degree of polarization with wave plate number, and 2 is degree of polarization change curves with wave plate number of total reflected light, and 3 is degree of polarization change curves with wave plate number of transmitted light.As can be seen from Figure 4, along with the increase of wave plate number, each degree of polarization all increases, and finally trends towards 100%.And can find out, reflected light has very high degree of polarization by wave-plate stack 1 again, and total degree of polarization Relative Transmission polarisation of light degree is totally improve a lot.When not used by reflected light, only have the degree of polarization of transmitted light, 13 blocks of wave plates just can reach the degree of polarization of 99%, and by apparatus of the present invention, after being used by the degree of polarization of reflected light, 11 blocks of wave plates just can make degree of polarization reach the degree of polarization of 99%.We according to the requirement to degree of polarization, can select suitable wave plate number.

In Fig. 5, θ is refraction angle, and the catadioptric light of incident ray only in two marginal rays as shown in Figure 5 (i.e. incidence point must between E, F) can be fully used.Consider marginal ray, suppose that wave-plate stack AB holds length to be L, gross thickness is d, beam effective diameter D, then EF=L-2*d*tan θ, AG=L-2*d*tan θ, beam diameter D=EF*sin θ, second catoptron 4 length AH=AG*tan θ, the length JK of quarter-wave plate 2 and the first catoptron equals beam diameter D, i.e. JK=D.Can be obtained by derivation above and have visible L and θ, d, D are relevant, and namely the length L of wave-plate stack 1 is by wave-plate stack material n ₂, wave-plate stack gross thickness d and beam diameter D determines.For non-edge light, provide the range of size of each device, beam effective diameter D≤EF*sin θ, the length AH >=AG*tan θ of the second catoptron 4, the length JK >=EF*sin θ of quarter-wave plate 2 and the first catoptron.Due to n ₁the refractive index of air, n ₂being the refractive index of material, is the attribute of material, and θ=90 °-θ _bcan know by inference beam diameter D, each device size all relevant with the material of wave-plate stack.

Because wave plate number N can be determined according to required degree of polarization, as can be seen from derivation above, when wave plate number N mono-timing, if the thickness of each block wave plate little, so the gross thickness d of wave-plate stack 1 is little, and beam diameter D is large, then the light entering wave-plate stack 1 is many, and light beam gross energy is large.So when degree of polarization one timing, wave plate number N is certain, the gross energy of the outgoing beam of thickness effect after wave-plate stack 1 of each block wave plate.

Those of ordinary skill in the art will be appreciated that, above embodiment is only used to the present invention is described, and be not used as limitation of the invention, as long as in spirit of the present invention, change the above embodiment, modification all will drop in the scope of claims of the present invention.

Claims (1)

1. an Efficient polarization purification devices, it is characterized in that: described purification devices is by wave-plate stack (1), quarter-wave plate (2), first catoptron (3) and the second catoptron (4) composition, wave-plate stack (1) surface normal direction is from the horizontal by Brewster angle, quarter-wave plate (2) and the first catoptron (3) vertical reflection light direction are placed, reflect s-polarized light is successively through quarter-wave plate (2), first catoptron (3) and quarter-wave plate (2), convert S polarized light to P polarized light, in the edge in the transmitted light direction of reflected light after wave-plate stack, vertical wave-plate stack (1) places the second catoptron (4),

The position of quarter-wave plate (2) and the first catoptron (3) according to debuging needs, can move in parallel at vertical reflection light direction;

Quarter-wave plate (2) is equal with the length AH of the first catoptron (3) length JK, the second catoptron (4) and be all more than or equal to beam diameter D, i.e. JK=AH >=D;

What wave-plate stack (1) adopted is fused quartz, or adopts CaF ₂, MgF ₂, K9 ultraviolet can be saturating optical material;

Each size determines relation: $L=\frac{D}{sin\mathrm{\θ}}+2*d*tan\mathrm{\θ},$ l and θ, d, D are relevant, and namely the length L of wave-plate stack (1) is by the refractive index n of wave-plate stack material ₂, air refractive index n ₁, wave-plate stack gross thickness d and beam diameter D determines, wherein, n ₁the refractive index of air, n ₂be the refractive index of wave-plate stack material, required wave plate number N can be determined according to the specific requirement of degree of polarization, the thickness of each block wave plate can be determined by wave-plate stack gross thickness d and wave plate number N