CN102169238B - Polarizing spectral device and application of polarizing spectral device in projection optical engine - Google Patents
Polarizing spectral device and application of polarizing spectral device in projection optical engine Download PDFInfo
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- CN102169238B CN102169238B CN201110123432.8A CN201110123432A CN102169238B CN 102169238 B CN102169238 B CN 102169238B CN 201110123432 A CN201110123432 A CN 201110123432A CN 102169238 B CN102169238 B CN 102169238B
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Abstract
The invention discloses a polarizing spectral device and application of the polarizing spectral device in a projection optical engine and relates to the polarizing spectral device. The polarizing spectral device can remarkably enlarge the range of an incident angle of a light beam and guarantee ideal degree of polarization. The polarizing spectral device is provided with a polarizing spectral film system and two optical prisms, wherein the polarizing spectral film system is formed by overlapping a plurality of transparent medium material layers; the polarizing spectral film system is plated between surfaces of bevelled edges of the two optical prisms; the bevelled edges of the two optical prisms are butted; and the two optical prisms are shaped like a right angled isosceles triangle respectively. The polarizing spectral device can serve as the polarizing spectral device in the projection optical engine based on a three-colour white light source.
Description
Technical field
The present invention relates to a kind of polarized light splitting device, especially relate to a kind of polarized light splitting device for three look white light source Projection Display and in the application of projecting optical engine.
Background technology
Recently, the Novel projector based on three-color light source (as LED, laser etc.) has become the focus on projection market, is considered to the developing direction of projection display technique of future generation.In projecting optical engine, one of conventional optical modulations realizes by changing modulated polarisation of light state.Polarized light splitting device is one of of paramount importance device in this type of miniature projection display system, and its effect is that incident beam is separated into transmitted light and reflected light two bundles, and two-beam has mutually perpendicular polarization state.
At present, the structure of polarized light splitting device has multiple.A kind of is the polarized light splitting device that utilizes the birefringent characteristic realization of crystal, as publication number " CN 1700057A " name is called the disclosed a kind of polarized light splitting device of application for a patent for invention of " a kind of polarization beam splitting method and device thereof ", use transparent birefringece crystal prism to form, according to the character of crystal, determine the cutting angle of this crystal, make to enter along optical axis direction normal incidence the light of crystal, after crystal interface generation total reflection, spatially decomposite the polarized light of the mutual vertical vibration of two bundles.Yet this polarizing beam splitter all has accurate requirement to the cutting angle of crystal and assembling, and birefringece crystal is of a high price, is not suitable for projecting optical engine.
The method stretching with multilayer polymer film has been invented by Minnesota Mining and Manufacturing Company, has made novel polarized light splitting device (US Patent No. 5,962,114).Although this polarized light splitting device superior performance, need to prepare the thin polymer film of multilayer, complex process.Polymeric material is stablized not as inorganic dielectric material in addition, and long-time use is easily aging, reduces optical characteristics.
Utilize deposit multilayer transparent dielectric material to make the method for polarization spectroscope, the earliest from the patent of invention (US Patent No. 2,403,731) of S.M.MacNeille.This polarization spectroscope adopts two kinds of refractive indexes to meet the material of Brewster angle relational expression, when normal incidence, can reach extraordinary degree of polarization, but its performance is very responsive to incident angle, normal use angle can not surpass ± 2 °, otherwise spectrum deterioration is very obvious.In addition, it also has requirement to the refractive index of material, if real material refractive index does not meet or skew Brewster angle relational expression, the p light transmission in spectral centroid region all can reduce.Problem for traditional MacNeille type polarizing beam splitter, Li Li has carried out improving design (L Li in 1996 to it, JA.Dobrowolski, Visible broadband, wide-angle thin-film multilayer polarizing beam splitter, Applied Optics, V.35,2221 (1996)), adopt four kinds of materials, wherein meet between two Brewster relational expression, finally in compared with polarizers of big angle scope, obtained higher average degree of polarization, by incident light allow angle expanded to ± 6 °.Its weak point is that the refractive index of requirement is difficult to search out corresponding material at occurring in nature, and the rete number using reaches 72 layers most.
Summary of the invention
The object of this invention is to provide and a kind ofly enlarge markedly beam incident angle degree scope, and guarantee the polarized light splitting device of desired polarization degree.
Another object of the present invention is to provide the application of described polarized light splitting device in projecting optical engine.
Described polarized light splitting device is provided with polarization beam splitter system and 2 optical prisms; Polarization beam splitter system consisted of plural transparent dielectric material stacked adding, and polarization beam splitter system is coated between the hypotenuse surface of 2 optical prisms, the docking of the hypotenuse of 2 optical prisms, described 2 optical prisms that optical prism is 2 right angled isosceles triangles.
Described plural transparent dielectric material layer is preferably 20～60 layers of transparent dielectric material layer.
Described polarization beam splitter is that best 2～4 kinds of material layer assembly in silicon oxide layer, magnesium fluoride layer, titanium oxide layer, tantalum oxide layers, niobium oxide layer, alumina layer, hafnium oxide layer and zirconia layer form.
Total physical thickness of described polarization spectro-film is preferably 2～6 μ m.
Described 2 optical prisms are preferably measure-alike, and 2 optical prisms are in same plane, and the refractive index of 2 optical prisms is all not less than the material of 1.7,2 optical prisms can be identical or different.
The hypotenuse docking of the described 2 optical prisms preferably hypotenuse of 2 optical prisms is bonding by optical cement, and 2 optical prisms form one.
Described polarized light splitting device can be used as the polarizing beam splitter in the projecting optical engine based on three look white light sources.
Compared with the prior art, the present invention has following outstanding advantages:
The present invention can carry out by the spectrum characteristic for three look white light sources the design of polarization beam splitter system, guaranteeing under the prerequisite of polarizing beam splitter performance, can greatly reduce the number of plies and the thickness of transparent dielectric material layer, its dichroism is reduced greatly to the susceptibility of incident angle of light, can enlarge markedly like this incident scope of light beam, and guarantee desired polarization degree.In addition, the present invention is simple in structure, and manufacture craft is simple, applies the present invention in projecting optical engine, can make the element that projecting optical engine is used reduce, and simple in structure, volume is small and exquisite, functional, and cost is applicable to batch production.
Accompanying drawing explanation
Fig. 1 is the structural representation of the embodiment of the present invention.
Fig. 2 is the normalization spectral distribution graph of the three-color LED light source that mates of the embodiment of the present invention.In Fig. 2, horizontal ordinate is wavelength Wavelength (nm), and ordinate is normalized spectral power Relative Spectral Power.
Fig. 3 is the refractive index profile distribution plan of the embodiment of the present invention.In Fig. 3, horizontal ordinate is physical thickness Physical Thickness (pm), and ordinate is refractive index Refractive Index.
Fig. 4 is embodiment of the present invention p optical transmission rate curve Tp while entering prism for light beam normal incidence.In Fig. 4, horizontal ordinate is wavelength Wavelength (nm), and ordinate is transmissivity Transmittance (%).
Fig. 5 is embodiment of the present invention s optical transmission rate curve Ts while entering prism for light beam normal incidence.In Fig. 5, horizontal ordinate is wavelength Wavelength (nm), and ordinate is transmissivity Transmittance (%).
Fig. 6 is embodiment of the present invention p optical transmission rate curve Tp while entering prism for ° oblique incidence of BEAM SQUINT vertical angle ± 7.4.In Fig. 6, horizontal ordinate is wavelength Wavelength (nm), and ordinate is transmissivity Transmittance (%);-7.4 ° of Tp of-expression,---represent+7.4 ° of Tp.
Fig. 7 is embodiment of the present invention s optical transmission rate curve Ts while entering prism for ° oblique incidence of BEAM SQUINT vertical angle ± 7.4.In Fig. 7, horizontal ordinate is wavelength Wavelength (nm), and ordinate is transmissivity Transmittance (%);-7.4 ° of Tp of-expression,---represent+7.4 ° of Tp.
Fig. 8 is for adopting the organigram of the projecting optical engine of the embodiment of the present invention.
Embodiment
Referring to Fig. 1, it is 3 and 2 right angled isosceles triangle optical prisms 1 and 2 that polarized light splitting device A is provided with polarization beam splitter.Polarization beam splitter system forms by multi-layer transparent dielectric material is stacking, polarization beam splitter system is coated between 2 optical prisms 1 and 2 hypotenuse surface, 2 optical prisms 1 and 2 hypotenuse are involutory bonding by optical cement, 2 optical prisms 1 and 2 form one, and 2 optical prisms 1 and 2 are measure-alike and be co-located in same plane.Arrow in Fig. 1 represents optical path direction.
2 optical prisms 1 and 2 are not less than 1.7 glass by refractive index and make (also can be other organic transparent materials, 2 optical prisms 1 and 2 material also can be different).The right angle face of 2 optical prisms can be coated with anti-reflection film (not drawing in Fig. 1) as required.
The polarization beam splitter of the present embodiment is 3 by titanium oxide layer, tantalum oxide layers, alumina layer and 4 kinds of transparent dielectric material layer of magnesium fluoride layer, to be constituted, film is that total number of plies is 41 layers, and film is that gross thickness is only approximately 3.2 μ m (order of every kind of needed number of plies of transparent dielectric material layer and 4 kinds of transparent dielectric material layer stack combinations all can design according to actual needs).Making polarization beam splitter is 3 o'clock, the transparent dielectric material layer of different refractivity is in layer deposited on 1 optical prism 1, after having deposited, together with just the optical prism 1 that is coated with polarization beam splitter system can being arrived with another 1 optical prism 2 use optics glue bond without plated film, thereby form above-mentioned polarized light splitting device.
Below provide the arrangement of transparent dielectric material layer of the present embodiment, the polarization spectro characteristic of the thickness of every layer of material and polarized light splitting device integral body.
The refractive index of 2 optical prisms selecting is 1.85.The refractive index of titanium oxide layer, tantalum oxide layers, alumina layer and the magnesium fluoride layer correspondence of selecting is respectively 2.4,2.2,1.67 and 1.38, is designated as respectively for simplicity H, M1, M2 and L.The initial configuration of film system is alternately comprised of the high and minimum bi-material H of refractive index and L, and the thickness of every one deck is determined by following formula:
λ wherein
reffor 550nm, n
mfor the refractive index of deposition materials, n
subrefractive index (the present embodiment is 1.85) for optical prism.The two replaces stacking number of cycles, and one is 15.Set up following evaluation function:
Wherein, the number that N is desired value, the spectral characteristic that C is current structure, is calculated by current structure.T is the spectral characteristic of dreamboat, and the light (p light) that polarization state is parallel to the plane of incidence reaches 100% in visible-range internal transmission factor, and polarization state reaches 100% perpendicular to the light (s light) of the plane of incidence in visible-range internal reflection rate.Tol is the tolerance that dreamboat allows, and its inverse is the weight of this desired value.
Referring to Fig. 2, the polarized light splitting device for three look white light source Projection Display of the present invention, by carrying out the design of film system for the feature of three look white light source spectrum.In Fig. 2, can find out, spectrum is not approximate equally distributed in visible-range, but at a (red), b (green) and three wave bands of c (indigo plant), has the emission peak of three certain widths, and its half-breadth is high arrives 50nm for 20nm.The spectrum peak of three kinds of colors is carried out to power ratio, make its synthesize white light, then the relative power spectrum after synthetic is as the weight of different wave length place desired value, sets up the new evaluation function for three-color light source spectrum.Adopt the pin type algorithm optimization rete number of plies and thickness, one of material M1, M2 of two kinds of middle refractive indexs or while are inserted into (if only allowing bi-material also can directly adopt this bi-material as " pin " layer) in original membrane architecture as " pin " layer.Calculating emulation shows, utilize the evaluation function of this introducing three-color light source spectrum to coordinate pin type algorithm to be optimized, requirement to Refractive Index of Material without fixed numbers relation, and the film of its optimal design system can obtain high degree of polarization under less number of plies condition, and have larger angle to accept scope.
Referring to Fig. 3, as seen from Figure 3, polarization beam splitter system consists of titanium dioxide, tantalum oxide, aluminium oxide and 4 kinds of materials of magnesium fluoride, and film is that total number of plies is 41 layers, and gross thickness is only approximately 32 microns.
Referring to Figure 4 and 5, can find out, for normal incidence, enter the light beam of optical prism, in three-color LED emission wavelength ranges, there is high p light transmission and low s light transmission (high s light reflectivity), and the relative power of light source emission wavelength is higher, polarized light splitting device more approaches dreamboat in the performance at this wavelength place.As calculated, its average degree of polarization can reach 0.997.
Referring to Fig. 6 and 7, can find out, for ° oblique incidence of BEAM SQUINT vertical angle ± 7.4, enter the light beam of optical prism, it still has high p light transmission and low s light transmission (high s light reflectivity) in three-color LED emission wavelength ranges, and its spectrum has the scope of accepting of 14.8 ° for beam angle.As calculated, within the scope of this, its average degree of polarization still can reach 0.992.
Polarized light splitting device A of the present invention is applied to three-color LED light source and the lower accessible angle range of application of LASER Light Source illumination and degree of polarization index referring to table 1.
Table 1
As can be seen from Table 1, angle range of application enlarges markedly, degree of polarization very good (the angle range of application of common polarized light splitting device one at ± 2.0 °, exceed after this scope, one can drop sharply to catoptrical degree of polarization below 0.950).
Referring to Fig. 8, three-color light source 4 sends three coloured light, as the light source of Projection Display light engine.Light-beam forming unit 5 is for the light of three-color light source 4 being changed into even rectangular light beam outgoing, and it comprises that the light beam that three-color light source 4 is sent closes the various mirror groups (not drawing in Fig. 8) of look conversion.Light-beam forming unit 5 shines s polarized light or the natural light only with certain convergent angle of polarized light splitting device A.Illumination by 5 outgoing of light beam integer type device is mapped to polarized light splitting device A above, and the s polarized light that it comprises is reflected on LCoS modulation panel 7.By the light after 7 modulation of LCoS modulation panel, by s polarized light, be converted into p polarized light, and carried image information.The p polarized light that carries image information enters on polarized light splitting device 7 again, and shines projection lens 8, and image is projected away.
Because the light inciding on polarized light splitting device A is not perpendicular to the incident of optical prism face, but there is the convergent beam of certain convergence angle, so the degree of polarization during except polarized light splitting device A vertical incidence, the applicable angular range of polarized light splitting device A also has influence on image quality and the luminous energy efficiency of optical projection system greatly, especially should be in the optical projection system of large convergent angle light beam.Polarized light splitting device A of the present invention carries out the design of film system by the spectrum characteristic for three-color light source 4, guaranteeing under the prerequisite of polarizing beam splitter performance, the number of plies and the thickness of required rete have been reduced, its characteristic is reduced greatly to the susceptibility of incident angle of light, can be in the incident of polarizers of big angle scope light beam.Therefore, apply the projecting optical engine of this polarized light splitting device A, can reduce the parameter request of optical projection system to other optical elements, reduce the production cost of optical projection system, meet market microminiaturization, light-weighted demand.
Claims (3)
1. a polarized light splitting device, be provided with polarization beam splitter system and 2 optical prisms, polarization beam splitter system consisted of plural transparent dielectric material stacked adding, it is characterized in that polarization beam splitter system is coated between the hypotenuse surface of 2 optical prisms, the hypotenuse docking of 2 optical prisms, described 2 optical prisms that optical prism is 2 right angled isosceles triangles; Described plural transparent dielectric material layer is 30～50 layers of transparent dielectric material layer; Described polarization beam splitter is that 3～4 kinds of material layer assembly stacks in silicon oxide layer, magnesium fluoride layer, titanium oxide layer, tantalum oxide layers, niobium oxide layer, alumina layer, hafnium oxide layer and zirconia layer form; Total physical thickness that described polarization beam splitter is is 2～6 μ m;
Determining of the number of plies of described plural transparent dielectric material layer and the one-tenth-value thickness 1/10 of every layer, needs to meet by following formula evaluation function F and coordinates the pin type algorithm can the value of being optimized, and described optimal value is minimum value:
In formula, the number that N is desired value; Tol
jfor red, green, blue three-color light source spectrum proportioning becomes after white light the inverse in the relative power spectrum value at certain desired value place; C
jfor the spectral characteristic of current structure at certain desired value place, by current structure, calculated; T
jfor the desired light spectral property at certain desired value place, the light that polarization state is parallel to the plane of incidence reaches 100% in visible-range internal transmission factor, and polarization state reaches 100% perpendicular to the light of the plane of incidence in visible-range internal reflection rate; The sequence number of a certain value in the alphabetical indication algebraically group that " j " represents to depend on;
Described 2 optical prisms are measure-alike, and 2 optical prisms are in same plane, and the refractive index of 2 optical prisms is all not less than 1.7.
2. a kind of polarized light splitting device as claimed in claim 1, the hypotenuse docking that it is characterized in that described 2 optical prisms is that the hypotenuse of 2 optical prisms is bonding by optical cement, 2 optical prisms form one.
3. a kind of polarized light splitting device as claimed in claim 1 or 2 is as the polarizing beam splitter in the projecting optical engine based on three look white light sources.
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| CN102435422B (en) * | 2011-09-22 | 2014-06-04 | 西安炬光科技有限公司 | Polarization test method and polarization test system of semiconductor laser |
| CN102928985B (en) * | 2012-10-28 | 2015-02-18 | 梧州奥卡光学仪器有限公司 | Spectroscope and coating process method thereof |
| CN105388625B (en) * | 2015-12-23 | 2018-11-13 | 浙江大学 | A kind of wearing display beam splitter and preparation method thereof |
| CN106094236A (en) * | 2016-08-21 | 2016-11-09 | 浙江蓝特光学股份有限公司 | A kind of polarization beam apparatus with optical thin film |
| CN108761624B (en) * | 2018-09-03 | 2023-10-24 | 中国科学院武汉物理与数学研究所 | Wedge-shaped polarization beam splitter prism with large incident field angle and ultrahigh extinction ratio |
| CN113718213A (en) * | 2021-04-26 | 2021-11-30 | 深圳市新邦薄膜科技有限公司 | Vacuum magnetic control coating method for light splitting film |
| CN113485063A (en) * | 2021-06-29 | 2021-10-08 | 歌尔股份有限公司 | Optical machine optical path system and control method thereof |
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| CN101477045A (en) * | 2009-01-16 | 2009-07-08 | 南京航空航天大学 | Glass prism SPR sensor detection system based on P polarized light |
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| JP2003114326A (en) * | 2001-10-04 | 2003-04-18 | Olympus Optical Co Ltd | Polarized beam splitter and optical apparatus using the polarized beam splitter |
| JP3812527B2 (en) * | 2002-09-26 | 2006-08-23 | コニカミノルタオプト株式会社 | Polarizing beam splitter |
| JP4596746B2 (en) * | 2003-04-17 | 2010-12-15 | 富士フイルム株式会社 | Optical element, optical system and projection projector apparatus |
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