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WO2001037030A1 - Ensemble de prisme biréfringent stable à la chaleur - Google Patents

Ensemble de prisme biréfringent stable à la chaleur Download PDF

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Publication number
WO2001037030A1
WO2001037030A1 PCT/IL2000/000746 IL0000746W WO0137030A1 WO 2001037030 A1 WO2001037030 A1 WO 2001037030A1 IL 0000746 W IL0000746 W IL 0000746W WO 0137030 A1 WO0137030 A1 WO 0137030A1
Authority
WO
WIPO (PCT)
Prior art keywords
polarizing
optical component
beam splitter
glass
component according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IL2000/000746
Other languages
English (en)
Inventor
Boaz Arnon
Inon Berent
Carina Reisin
Rony Reuveni
Michael Gutin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Unic View Ltd
Original Assignee
Unic View Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Unic View Ltd filed Critical Unic View Ltd
Priority to AU12980/01A priority Critical patent/AU1298001A/en
Publication of WO2001037030A1 publication Critical patent/WO2001037030A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3016—Polarising elements involving passive liquid crystal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements

Definitions

  • the present invention relates to the field of prismatic polarizing beam splitter assemblies, especially for use in applications requiring high light intensities.
  • polarizing and the splitting of the beams in such systems is performed by means of a polarizing beam splitter, which typically consists of a pair of transmissive prisms, between which is sandwiched a thin film stack, or a material with anisotropic optical density, such as an oriented liquid crystal layer or liquid crystal polymeric layer.
  • the purpose of the prisms is to ensure that the incoming light is incident on the thin layer at such an angle as to ensure correct polarization. It is well known that unwanted changes in the polarization can be caused either by residual birefringence arising from non-homogeneous cooling of the transmissive material during manufacture, or by stress birefringence arising from improper mechanical assembly or clamping of the components.
  • Residual birefringence can be minimized by using materials such as highly annealed glasses, which have very low residual birefringence. Stress birefringence can be minimized by using well designed, low-stress mounts for the optical components.
  • Use of such prior art polarizing beam splitters at high light intensities have not generally resulted in sufficient optical performance, as manifested by severe degradation of the extinction ratio of such polarizing beam splitters.
  • the attempts to increase the thermal stability of the beam splitter and thus to overcome this problem have, in the main, been directed at the ability of the polarization- separating layer to withstand the high local temperatures generated by such high power beams.
  • the present invention thus seeks to provide a new polarizing beam splitter which is thermally stable, as a result of overcoming the effects of thermally induced stress birefringence by means of specifically selecting and using a prism material with a low optical stress coefficient.
  • the interpretation of what constitutes a thermally stable polarizing beam splitter is determined by the absence of significantly noticeable changes in polarization performance when the beam splitter is used in its intended application at its maximum or rated power level.
  • a thermally stable polarizing beam splitter consisting of two prisms constructed of a material with a low optical stress coefficient, between which is sandwiched an aligned liquid crystal layer or liquid crystal polymeric layer, or a thin film stack.
  • the material is selected to have at least one additional property, selected from a low thermal expansion coefficient, a low Young's Modulus, and a high thermal diffusion coefficient.
  • the prism material is a glass such as SF 6 manufactured by the Schott Glaswerke of Mainz. Germany, or the glass FeD E05-25 manufactured by Corning Optical Glasses of Avon, France, or the glass FD6 manufactured by the HOYA o
  • polarizing beam splitter can be successfully utilized in the construction of high performance compact designs of projection systems, such as those described in US Patents Nos. 5.833.338 and 5.946,139. and in the co-pending U.S. Patent Application No. 09/056107. Furthermore, since both polarization channels are of sufficiently high performance, and no additional polarization filtration is needed, the polarizing beam splitter can be utilized in a configuration where it operates both as a polarizer and an analyzer in a single element.
  • the present invention is also equally applicable for use in recombinant polarizing beam splitters, popularly known as 100% cubes, such as are described in U.S. Patent No. 4,913.529 to J. F. Goldenberg and J. D. Eskin.
  • a polarizing optical component consisting of at least one transparent element having a low optical stress coefficient such that, when used at its rated luminous power level, significantly noticeable thermally induced stress birefringence effects are absent, so that the component is thermally stable.
  • a polarizing component as described above, and wherein the optical stress coefficient is less than lxlO "6 mm 2 /N.
  • a polarizing component as described above, and containing two transparent elements.
  • a polarizing component as described above, and wherein the transparent element also has at least one of the properties selected from the group consisting of high thermal diffusion coefficient, low Young's modulus and low thermal expansion coefficient.
  • a polarizing component as described above, and wherein the material from which the transparent element is made is a glass, which could be one of the type SF 6. SF 57. FeD E05-25 or FD6.
  • a polarizing component as described above, and wherein the glass has a refractive index greater than 1.7 in the visible range.
  • a polarizing component as described above, and having a thin film stack interposed between the two transparent elements.
  • polarizing component consisting of at least one transparent element constructed of a glass of the type SF 6.
  • a projection system consisting of at least one polarizing beam splitter constructed of a glass of one of the types SF 6, SF 57, FeD E05-25 or FD6.
  • a method of constructing a transparent element of a polarizing component consisting of the steps of selecting a set of suitable materials for the transparent element, the materials having a low optical stress coefficient, and selecting from the set.
  • a material additionally having at least one of the parameters selected from the group consisting of a high thermal diffusion coefficient, a low thermal expansion coefficient, and a low Young's modulus.
  • the optical stress coefficient preferably has a value of less than lx lO "6 mm 2 /N.
  • Fig. 1 schematically illustrates a polarizing beam splitter, constructed and operative according to a preferred embodiment of the present invention:
  • Fig. 3 is a graph showing the results of an experiment comparing the thermally induced stress birefringence in BK 7 glass, and in SF 6 glass:
  • Fig. 4 is a table showing the results of experiments comparing the thermally induced stress birefringence in 7 different types of glass.
  • Fig. 1 schematically illustrates a polarizing beam splitter 10, constructed and operative according to a preferred embodiment of the present invention.
  • the embodiment shown in Fig. 1 is used as an example of a class of optical components whose operation depends on their polarizing properties, and which are used for the transmission of high intensity optical beams, where the performance of the system in which they are used is sensitive to the level of polarization maintained.
  • the polarizing beam splitter is constructed of two prisms. 12 14. of an optical grade glass. Between the prisms is sandwiched a birefringent layer 16 of anisotropic optical material, such as an aligned liquid crystal layer or liquid crystal polymeric layer, or a thin film stack.
  • An incident beam of light 18 enters the prism 14 and is incident on the birefringent layer 16. where it undergoes polarization.
  • the ordinary beam Po undergoes total internal reflection, and exits from the prism 22 diverted from the incident beam direction.
  • the extraordinary beam Pe. 20 passes straight through the beam splitter undiverted.
  • the refractive index of the glass In order to achieve a high extinction ratio, the refractive index of the glass must be as close as possible to the high refractive index of the birefringent layer.
  • the difference between the high refractive index and the low refractive index of the birefringent layer is known as ⁇ n.
  • the higher the value of ⁇ n. the larger the acceptance angle at which the ordinary polarized light is reflected, and hence the larger the acceptance angle for which the prism operates as a polarizer.
  • Use of a layer having a high ⁇ n thus also allows the use of smaller prisms without reducing the active aperture of the component.
  • Liquid crystal and liquid crystal polymers have large values of ⁇ n and therefore are suitable for this type of polarizing beam splitter, as is known in the art.
  • the value of the low refractive index for these material is of the order of 1.5 and thus to achieve a large value of ⁇ n, the high refractive index should preferably be more than 1.7.
  • the refractive index of the material of the prism must, therefore, also be at least 1.7.
  • SF 6 SF 6
  • the refractive index of SF 6 is 1.805 for light at a wavelength of 588 run, while that of SF 57 is about 1.847 at 588 run.
  • the most suitable material of construction for the prisms according to this preferred embodiment of the present invention is SF 6, or a similar glass from another manufacturer.
  • optical stress coefficient is probably the most important factor in the selection of a glass with the minimum level of thermally induced stress birefringence for use in polarizing beam splitters, there are other properties which contribute to the level of this birefringence, and which must therefore be optimized in order to achieve the best possible performance from the component.
  • a temperature gradient within the material causes stresses due to non-uniform expansion.
  • the thermal expansion of the material is proportional to the coefficient of expansion of the material, ⁇ .
  • a parameter P can be defined, proportional to a positive power of ⁇ , E and K and to a negative power of D. The lower the value of this parameter, the less the degeneration of the polarization state of the beam passing through the polarizing beam splitter.
  • the power to which each of the arguments in P should be raised depends on the component geometry, on the component heating and cooling rates and on the heat flow pattern inside the component.
  • Fig. 2. shows schematically an experimental arrangement for measuring the change in the polarization of light passing through a glass slab heated at a steady rate to a fixed temperature.
  • the glass slab 30 under test is located on an electric hot plate 32. whose temperature is allowed to rise after switch-on to a final set value.
  • a source of light 34 which can be either a non-polarized laser giving essentially monochromatic light, or an incoherent source, such a lamp, giving a broadband spectrum of light, dispatches a beam 36 through the slab as it heats up. Before passing through the slab, the beam is polarized by means of a polarizing element 38.
  • the polarization is detected by means of a power meter 40 which determines the power level of the light after passing through an analyzer 42, which could be a polarizer crossed with respect to the polarizer 38.
  • an analyzer 42 which could be a polarizer crossed with respect to the polarizer 38.
  • the power read is virtually zero, since the polarizers are essentially crossed, and the slab, if correctly manufactured and annealed, should have negligible residual birefringence. As the glass slab heats up, any change in the birefringence level of the glass results in a significant change in the power detected, as part of the light incident on the analyzer now becomes transmitted therethrough. This apparatus is therefore capable of detecting very slight changes in birefringence.
  • Fig. 3. shows a graph of the results of an experiment comparing the thermally induced stress birefringence in two glasses manufactured bv the the Schott Glastechnike of Mainz. Germanv - BK 7. which is a common borosilicate glass, widely used to construct the prisms used in prior art polarizing beam splitters, and SF 6. as preferably used as the material of the prisms of a polarizing beam splitter, constructed and operative according to a preferred embodiment of the present invention.
  • the graph shows the detected power in watts, as a function of the elapsed time from turning on the hotplate. For reference purposes, it should be noted that the heating surface itself takes about 180 seconds to reach its working temperature.
  • the thermally induced stress birefringence rises to a high value, represented by a rise in the detected light power measured through the crossed polarizers. This steep rise to a maximum as the block heats up is to be expected, since it is at this stage that the temperature gradients through the slab are at their highest level, and the induced stresses thus at their highest level.
  • the maximum level of thermally induced stress birefringence is only about one tenth of the maximum level for the BK 7 glass sample.
  • Fig. 4. is a table showing the results of these experiments, in addition to the results of the hot plate experiments, performed on 6 of the 7 glasses.
  • the table shows the optical contrast obtained after passage through the crossed polarizers, this being a more useful measure of .
  • the dominant source for the heating of the prism is the absorption of light, as is the case in a practical polarizing beam splitter used in an optical projection system, then the specific absorption of the material should also be taken into account.
  • the absorption that should be used is a weighted average over the entire spectrum of the light source.
  • a polarizing beam splitter with an entrance surface of dimensions 55mm x 44 mm, an optical path length of 80 mm and an acceptance angle range of ⁇ 10°, was constructed using prisms of SF 6 glass.
  • This polarizing beam splitter showed negligible reduction in performance when subjected to the thermal gradients generated when used inside a high brightness projection system, at an average power density of 2 W/cm . Even at this power level, extinction ratios of greater than 1000:1 and 500:1 were obtained for the transmitted and reflected beams respectively, these results being significantly better than those obtained form prior art beam splitters.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)

Abstract

L'invention concerne un composant optique de polarisation thermostable, comme un diviseur de faisceau de polarisation qui permet de réduire les effets de la biréfringence à contraintes induites par un phénomène thermique en utilisant un ou plusieurs éléments construits en un matériau présentant un faible coefficient de contrainte optique, en général, moins de 1 x 10-6 mm2/N. Un matériau de ce type réduit les contraintes thermiques dues au passage du faisceau lui-même, soit en raison de la section transversale de faisceau non uniforme qui chauffe certaines parties de l'élément plus que les autres parties, ou en raison de la section de faisceau uniforme qui présente une dissipation de chaleur non uniforme à partir des surfaces de l'élément. La présence de contraintes thermiques dans l'élément se traduit par une biréfringence induite par contraintes en raison du coefficient de contraintes optiques. En outre, la biréfringence de contraintes induites par la chaleur est réduite par l'utilisation de matériaux qui diminuent la formation de gradients thermiques eux-mêmes ou réduisent le niveau de contraintes mécaniques provoquées par des gradients thermiques néanmoins présents.
PCT/IL2000/000746 1999-11-14 2000-11-14 Ensemble de prisme biréfringent stable à la chaleur Ceased WO2001037030A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12980/01A AU1298001A (en) 1999-11-14 2000-11-14 Thermally stable birefringent prism assembly

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IL13292899A IL132928A0 (en) 1999-11-14 1999-11-14 Thermally stable birefringent prism assembly
IL132928 1999-11-14

Publications (1)

Publication Number Publication Date
WO2001037030A1 true WO2001037030A1 (fr) 2001-05-25

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PCT/IL2000/000746 Ceased WO2001037030A1 (fr) 1999-11-14 2000-11-14 Ensemble de prisme biréfringent stable à la chaleur

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AU (1) AU1298001A (fr)
IL (1) IL132928A0 (fr)
WO (1) WO2001037030A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003015420A1 (fr) * 2001-08-06 2003-02-20 Advanced Digital Optics, Inc. Systeme de gestion chromatique
US6857747B2 (en) 2001-08-06 2005-02-22 Advanced Digital Optics, Inc. Color management system
US6893130B2 (en) 2001-08-06 2005-05-17 Advanced Digital Optics, Inc. Color management system having a field lens
US6899432B2 (en) 2001-08-06 2005-05-31 Advanced Digital Optics, Inc. Color management system having a transmissive panel and optical isolator
US6945654B2 (en) 2001-08-06 2005-09-20 Jds Uniphase Corporation Color management system having a prism to compensate for optical aberrations and to enhance contrast
DE102005060517A1 (de) * 2005-12-12 2007-06-21 Carl Zeiss Smt Ag Belastungsfester Prismenpolarisator

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4913529A (en) * 1988-12-27 1990-04-03 North American Philips Corp. Illumination system for an LCD display system
US5042925A (en) * 1989-11-14 1991-08-27 U.S. Philips Corporation Polarization-sensitive beam splitter having a polarizing birefringent oriented polymer adhesive layer
US5245472A (en) * 1991-06-26 1993-09-14 Hughes Aircraft Company High-efficiency, low-glare X-prism
WO1995013561A1 (fr) * 1993-11-12 1995-05-18 Hughes-Jvc Technology Corporation Systeme de projection a modulateur de lumiere a cristaux liquides comprenant un compensateur et composition de substrat de contre-electrode
JPH07218723A (ja) * 1994-02-07 1995-08-18 Nikon Corp 偏光子
WO1997024637A1 (fr) * 1996-01-03 1997-07-10 Hughes-Jvc Technology Corporation Convertisseur de polarisation losangique de type fresnel
US5808795A (en) * 1995-03-06 1998-09-15 Nikon Corporation Projection type display apparatus
DE19826637A1 (de) * 1997-06-17 1998-12-24 Hoya Corp Lichtpolarisationssteuerelement unter Verwendung von Glas mit spannungsoptischem Koeffizienten und Verfahren zur Herstellung des Glases mit spannungsoptischem Koeffizienten
US5946139A (en) * 1998-04-06 1999-08-31 Unic View Ltd. Compact monitor
US5969861A (en) * 1994-02-07 1999-10-19 Nikon Corporation Polarizing optical system
EP0991281A2 (fr) * 1998-09-29 2000-04-05 Sony Corporation Dispositif de projection d'images

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4913529A (en) * 1988-12-27 1990-04-03 North American Philips Corp. Illumination system for an LCD display system
US5042925A (en) * 1989-11-14 1991-08-27 U.S. Philips Corporation Polarization-sensitive beam splitter having a polarizing birefringent oriented polymer adhesive layer
US5245472A (en) * 1991-06-26 1993-09-14 Hughes Aircraft Company High-efficiency, low-glare X-prism
WO1995013561A1 (fr) * 1993-11-12 1995-05-18 Hughes-Jvc Technology Corporation Systeme de projection a modulateur de lumiere a cristaux liquides comprenant un compensateur et composition de substrat de contre-electrode
JPH07218723A (ja) * 1994-02-07 1995-08-18 Nikon Corp 偏光子
US5969861A (en) * 1994-02-07 1999-10-19 Nikon Corporation Polarizing optical system
US5808795A (en) * 1995-03-06 1998-09-15 Nikon Corporation Projection type display apparatus
WO1997024637A1 (fr) * 1996-01-03 1997-07-10 Hughes-Jvc Technology Corporation Convertisseur de polarisation losangique de type fresnel
DE19826637A1 (de) * 1997-06-17 1998-12-24 Hoya Corp Lichtpolarisationssteuerelement unter Verwendung von Glas mit spannungsoptischem Koeffizienten und Verfahren zur Herstellung des Glases mit spannungsoptischem Koeffizienten
US5946139A (en) * 1998-04-06 1999-08-31 Unic View Ltd. Compact monitor
EP0991281A2 (fr) * 1998-09-29 2000-04-05 Sony Corporation Dispositif de projection d'images

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 11 26 December 1995 (1995-12-26) *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003015420A1 (fr) * 2001-08-06 2003-02-20 Advanced Digital Optics, Inc. Systeme de gestion chromatique
US6851812B2 (en) 2001-08-06 2005-02-08 Advanced Digital Optics, Inc. Color management system
US6857747B2 (en) 2001-08-06 2005-02-22 Advanced Digital Optics, Inc. Color management system
US6893130B2 (en) 2001-08-06 2005-05-17 Advanced Digital Optics, Inc. Color management system having a field lens
US6899432B2 (en) 2001-08-06 2005-05-31 Advanced Digital Optics, Inc. Color management system having a transmissive panel and optical isolator
US6945654B2 (en) 2001-08-06 2005-09-20 Jds Uniphase Corporation Color management system having a prism to compensate for optical aberrations and to enhance contrast
US6971747B2 (en) 2001-08-06 2005-12-06 Jds Uniphase Corporation Image display device having a compensating prism group
CN100450189C (zh) * 2001-08-06 2009-01-07 Jds单相公司 色彩管理系统
DE102005060517A1 (de) * 2005-12-12 2007-06-21 Carl Zeiss Smt Ag Belastungsfester Prismenpolarisator

Also Published As

Publication number Publication date
AU1298001A (en) 2001-05-30
IL132928A0 (en) 2001-03-19

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