CN100458495C - Spectroscopic prism of multiple incidence direction - Google Patents

Abstract

A light splitting prism with multi-coming direction is prepared as setting light spitting body in cavity of incoming body, setting transition surface of incoming body and light splitting body to be polarized light splitting surface and arranging polarized light splitting film on polarized light splitting surface.

Description

The Amici prism of multiple incidence direction

Technical field

The present invention relates to Amici prism (PBS) structure Design, belong to the technical field of optical-mechanical system Application Design.

Background technology

The miniscope spare that utilizes the reflective principle of light to show shows (DMD), liquid crystal on silicon demonstration (LCoS) etc. need be incided device surface with light when working after to be come out by display reflects as digital micro mirror, amplify by optical system by tieing up the images that display produced with small-sized 2 after the optical system, and finally realize the full figure visual effect.This class display belongs to novel reflective display technique as a kind of novel image source, has high resolving power, high light utilization ratio, manufacturing technology than characteristics such as maturation and low-power consumption.

Liquid crystal has the part crystal property, can show the distinctive anisotropy of crystal to incident light, so nearly all need to use light beam work in liquid crystal display device, (LCoS) is no exception for liquid crystal on silicon.The light that the led light source of selecting for use in the LCoS light engine sends is natural light, this natural light need be converted into polarized light through the polarizer.And polarized light can be mutually vertical with two direction of vibration, the related linearly polarized light of phase place describes, and is typically expressed as P polarized light and S polarized light, wherein P polarized light polarization direction is parallel to the plane of incidence, and S polarized light polarization direction is perpendicular to the plane of incidence.Selected polarization splitting prism (PBS) in the LCoS light engine for use, polarization light-dividing surface can allow the P polarized light pass through the reflection of S polarized light.

By the optics background knowledge as can be known, when light from a kind of medium under the oblique situation that is mapped to another kind of medium, increase along with incident angle, the dull rising always of the light intensity reflectivity of S (senkrecht is vertical) component, but the light intensity reflectivity of P (parallel is parallel) component descended before this, at certain special angle i _BDrop to 0, rise again thereafter.Making P component reflectivity is zero incident angle i _BBe called Brewster angle (D.Brewster, 1815).By the amplitude reflectivity formula as can be known, when light be n from refractive index ₁Medium to incide refractive index be n ₂Medium the time, the expression formula of Brewster angle is

$i_B={\tan }^{-1}\frac{n_2}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20061009789500072.png,C20061009789500081.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}$

For the situation n of air to glass ₂/ n ₁～1.5, i _B～57 °.

Prism PBS is according to the design of Mac Neille method, and its main thought is to make the incident angle of each face in the rete satisfy Brewster angle, and the transmitance of the P polarized light of incident ray on these faces is near 100% like this; And for the S polarized light, these retes constitute a highly reflecting films system, thereby can to make S reflection of light rate theoretically be 100%.

Now generally adopt the method that on polarization light-dividing surface, is coated with the multilayered medium polarization beam splitter to make that PBS can play good spectrophotometric result when light splitting surface and bottom surface were 45.

After incident light enters PBS, PBS can enter the imaging of LCoS image-forming module with incident light (S polarized light) reflection, again because the inherent characteristic of liquid crystal, the S polarized light that enters the LCoS image-forming module is changed into the P polarized light, reflect from the LCoS image-forming module, penetrate through PBS again, again through lens imaging system obtain LCoS go up image amplification picture.

In order to realize that high-amplification-factor, statuette difference show, require the lens combination effective focal length enough little, and between last minute surface of lens combination and LCoS display panel, must settle a PBS, so the lens combination effective focal length must be greater than the thickness of PBS, thereby will reduce the thickness that the lens combination effective focal length must reduce PBS.Therefore Amici prism (PBS) thickness d is the smaller the better; Simultaneously, show, wish that PBS light projector area S is the bigger the better in order to realize high brightness.

Digital Light Processor (DLP, Digital Light Processing) technology is the epoch-making revolution in demonstration field, and it will turn over a new page for video-projection shows.It with DMD (Digital Micromirror Device) as image device.When it in when work, white light passes TIR (Total Internal Reflrction) prism.The effect of TIR prism is to adjust light to be mapped to incident angle on the DMD, when making micromirror on the DMD rotate, light can be injected exactly or departed from projecting lens.The texture ratio of TIR prism is more single now, has limited the application of DMD, is necessary to design the prism structure that makes new advances, to improve the performance of DMD.

Summary of the invention

Technical matters: the structure that the objective of the invention is to propose a kind of novel Amici prism, this structure is very different with the structure of traditional Amici prism of using always at present, make the light splitting surface of light splitting surface and traditional cube shaped PBS that very big change arranged, under the long-pending situation of equal light-emitting face, greatly reduce the thickness (thickness be about original half) of PBS, and make light source light projector area increase, help to realize that high brightness shows.

Technical scheme: the present invention relates to three kinds of Amici prism new structures, it constitutes by going into beam, beam split body and polarization beam splitter, the beam split body is arranged in the cavity of beam, and the interface of going into beam and beam split body is a polarization light-dividing surface, is manufactured with polarization beam splitter on the polarization light-dividing surface.

Go into beam and beam split body bottom surface radius of common formation and the high right cylinder that equates, wherein the beam split body is the cone of an and same bottom surface coaxial with right cylinder, its bottom surface radius equates that with high the conical surface of beam split body is a polarization light-dividing surface, is manufactured with polarization beam splitter on the polarization light-dividing surface.

Go into beam and beam split body common constitute a bottom surface for square, highly be half rectangular parallelepiped of the square length of side, wherein the beam split body be one with rectangular parallelepiped altogether square bottom surface, half square cone that equates with height of central shaft and the bottom surface length of side altogether, the conical surface of beam split body is a polarization light-dividing surface, is manufactured with polarization beam splitter on the polarization light-dividing surface.

Go into that beam and beam split body are common to be constituted a bottom surface and be rectangle, highly grow half rectangular parallelepiped of edge lengths for the bottom surface rectangle, wherein the beam split body is that a bottom surface is a rectangle, the master looks the ridge triangular prism that the side is an isosceles right triangle, two ridge faces of form right angle are polarization light-dividing surface, are manufactured with polarization beam splitter on the polarization light-dividing surface.

Beneficial effect: the present invention has changed the situation of traditional cube shaped PBS light from a side incident, make under the prerequisite that does not reduce total light splitting surface area, both greatly reduce the thickness (approximately reducing half) of Amici prism (PBS), increased the light projector area of incident light again.Light can enter polarization light-dividing surface from different directions, can adopt a plurality of light sources to improve catoptrical luminous flux.This technology can be applied in the reflection type display devices such as LCoS, DMD.

Description of drawings

Fig. 1 is the synoptic diagram of the cylinder bodily form Amici prism that completes, wherein has into beam 1, polarization light-dividing surface 2, beam split body 3, polarization beam splitter 4, incident light 5, logical light face 6, anti-reflection film 7, P polarized light 8, S polarized light 9.

Fig. 2 is the synoptic diagram of first kind of cuboid Amici prism completing.

Fig. 3 is the synoptic diagram of second kind of cuboid Amici prism completing, and the long limit 10 of bottom surface rectangle is wherein arranged.

Embodiment

Embodiments of the invention are respectively: as shown in Figure 1, go into beam and beam split body bottom surface radius of common formation and the high right cylinder that equates, wherein the beam split body is the cone of an and same bottom surface coaxial with right cylinder, its bottom surface radius equates with high, the conical surface of beam split body is a polarization light-dividing surface, is manufactured with polarization beam splitter on the light splitting surface.

As shown in Figure 2, go into beam and beam split body common constitute a bottom surface for square, highly be half rectangular parallelepiped of the square length of side, wherein the beam split body be one with rectangular parallelepiped altogether square bottom surface, half square cone that equates with height of central shaft and the bottom surface length of side altogether, the conical surface of beam split body is a polarization light-dividing surface, is manufactured with polarization beam splitter on the polarization light-dividing surface.

As shown in Figure 3, go into that beam and beam split body are common to be constituted a bottom surface and be rectangle, highly grow half rectangular parallelepiped of edge lengths for the bottom surface rectangle, wherein the beam split body is that a bottom surface is a rectangle, the master looks the ridge triangular prism that the side is an isosceles right triangle, two ridge faces of form right angle are polarization light-dividing surface, are manufactured with polarization beam splitter on the polarization light-dividing surface.

The cemented surface of going between beam and the beam split body is a polarization light-dividing surface, has been coated with the multilayered medium polarization beam splitter on the polarization light-dividing surface; The angle of polarization light-dividing surface and bottom surface is 45 °.After the incident light of random polarization state is injected prism perpendicular to the logical light face of going into beam, on polarization light-dividing surface, incident light is polarized spectro-film and is divided into the different light beam of two bundles, have parallel state and vertical attitude polarization direction respectively, usually be expressed as P polarized light and S polarized light respectively, wherein the P polarized light sees through polarization light-dividing surface, and the S polarized light is polarized the light splitting surface reflection, thereby makes P polarized light and S polarized light separately.

This novel Amici prism is characterized in that its polarization light-dividing surface is not to be made of a plane, and light no longer enters Amici prism from single direction, thereby can adopt a plurality of light sources to improve catoptrical luminous flux.

On the logical light face of Amici prism, be coated with anti-reflection film, the reflection loss when entering Amici prism to reduce light.

Claims (3)

1. the Amici prism of a multiple incidence direction, it is characterized in that: it constitutes by going into beam (1), beam split body (3) and polarization beam splitter (4), beam split body (3) is arranged in the cavity of beam (1), the interface of going into beam (1) and beam split body (3) is polarization light-dividing surface (2), is manufactured with polarization beam splitter (4) on the polarization light-dividing surface (2).

2. the Amici prism of multiple incidence direction according to claim 1, it is characterized in that constituting a bottom surface radius and the high right cylinder that equates jointly into beam (1) and beam split body (3), wherein beam split body (3) is the cone of an and same bottom surface coaxial with right cylinder, its bottom surface radius equates with high, the conical surface of beam split body (3) is polarization light-dividing surface (2), is manufactured with polarization beam splitter (4) on the polarization light-dividing surface (2).

3. the Amici prism of multiple incidence direction according to claim 1, it is characterized in that into beam (1) and beam split body (3) constitute jointly a bottom surface for square, highly be half rectangular parallelepiped of the square length of side, wherein beam split body (3) be one with rectangular parallelepiped altogether square bottom surface, half square cone that equates with height of central shaft and the bottom surface length of side altogether, the conical surface of beam split body (3) is polarization light-dividing surface (2), is manufactured with polarization beam splitter (4) on the polarization light-dividing surface (2).

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