WO2013057636A1 - Source de lumière polarisée à luminance élevée - Google Patents

Source de lumière polarisée à luminance élevée Download PDF

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Publication number
WO2013057636A1
WO2013057636A1 PCT/IB2012/055500 IB2012055500W WO2013057636A1 WO 2013057636 A1 WO2013057636 A1 WO 2013057636A1 IB 2012055500 W IB2012055500 W IB 2012055500W WO 2013057636 A1 WO2013057636 A1 WO 2013057636A1
Authority
WO
WIPO (PCT)
Prior art keywords
light source
conversion elements
oriented
luminescent material
light
Prior art date
Application number
PCT/IB2012/055500
Other languages
English (en)
Inventor
Uwe Mackens
Ulrich Weichmann
Original Assignee
Koninklijke Philips Electronics N.V.
Philips Intellectual Property & Standards Gmbh
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 Koninklijke Philips Electronics N.V., Philips Intellectual Property & Standards Gmbh filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2013057636A1 publication Critical patent/WO2013057636A1/fr

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/505—Wavelength conversion elements characterised by the shape, e.g. plate or foil
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
    • H01S5/0087—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping for illuminating phosphorescent or fluorescent materials, e.g. using optical arrangements specifically adapted for guiding or shaping laser beams illuminating these materials

Definitions

  • the invention relates to a solid-state light source for emitting polarized light and a method of generating polarized light for use in projection applications.
  • Solid-state light sources are currently entering many different lighting applications and replace the traditional incandescent and gas discharge lamps.
  • solid state refers commonly to light emitted by solid-state electroluminescence, as opposed to incandescent bulbs (which use thermal radiation) or fluorescent tubes.
  • incandescent lighting soli-state lighting creates visible light with reduced heat generation or parasitic energy dissipation.
  • Most common "white” light emitting diodes (LEDs) convert blue light from a solid-state device to an (approximate) white light spectrum using
  • the beam will be unpolarized. Even applying ceramic material will emit unpolarized light due to its polycrystalline and unoriented character. As a consequence, polarization has to be recovered at the expense of brightness in complex optical setups.
  • 3D- displays are gaining importance in the markets of digital cinema and television (TV).
  • the 3D-display technology relies in most cases on polarized light, which is realized by splitting the beam from lamps with the use of complex and expensive polarization optics.
  • High intensity gas discharge lamps like for example ultra high performance (UHP) or Xenon- lamps are currently used in these demanding applications, but suffer from polarization recovery of the beam.
  • solid-state light sources are also highly desired as the light source in this type of applications.
  • a setup of a RGB conversion module in projection applications using lasers has for example been realized by a hybrid solution and consists of at least three components: the exciting laser diodes, the converting phosphor and a LED. Blue color is used directly from the laser diodes which also acts as excitation source for the green- converting phosphor. The red color is emitted directly by a LED.
  • this hybrid setup is still limited in brightness, e.g. for LCD technology, and therefore not adapted to low
  • Polarized light emitting elements can be coupled directly into the display without any additional losses caused by polarization recovery or filtering. This means that there are basically no polarization losses to be expected, which makes polarized light emitting elements a very attractive light source for these applications. Still some issues remain and make the direct use of lasers in these applications difficult. First, suitable lasers are not available at all required emission wavelengths. Secondly, even with the right lasers available, safety and image quality issues (Speckle) remain as problems that have to be solved using additional measures.
  • the beam generator may comprise a laser source for generating a pumping laser beam. This provides the advantage that a highly efficient point-shaped excitation of the oriented luminescent material can be achieved by the laser beam.
  • the at least one conversion element may be adapted to generate the polarized beam at a wavelength different from the exciting wavelength of the light beam. Thereby, a polarized beam of a predetermined wavelength can be generated at high intensity.
  • the heat sink may be arranged as a moving element on which a plurality of conversion elements are arranged so that the light beam selectively illuminates the conversion elements when the moving element moves.
  • the light beam is preferentially a focussed light beam.
  • the moving element may be a spinning wheel and the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the orientation of the oriented luminescent material of all conversion elements is substantially parallel.
  • the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the orientation of the oriented luminescent material of all conversion elements is substantially parallel.
  • the moving element may be a spinning wheel and the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the orientation of the oriented luminescent material of all conversion elements is substantially tangential or radial to the spinning wheel.
  • the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the orientation of the oriented luminescent material of all conversion elements is substantially tangential or radial to the spinning wheel.
  • the moving element may be a spinning wheel and the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the oriented luminescent material of the conversion elements has alternating radial and tangential orientation with respect to the spinning wheel.
  • the conversion elements may be arranged at the circumference of the spinning wheel in such a manner that the oriented luminescent material of the conversion elements has alternating radial and tangential orientation with respect to the spinning wheel.
  • said conversion elements may be used in a reflection or transparent mode.
  • a flexible arrangement can be achieved by suitably selecting the mode of the conversion elements.
  • the oriented luminescent material may comprise an oriented ceramic or crystal. More specifically, the oriented luminescent material may comprise or may be selected from Pr:YLF, Nd:YLF, Ho:YLF, Yb:NaYF 4 , Yb:Er:NaYF 4 , Ho:NaYF 4 ,
  • Fig. 1 shows a schematic setup of a light source for generating a polarized light beam with high luminance according to a first embodiment
  • Fig. 2 shows a schematic arrangement of a dynamic application with tangential and radial alignment of segments according to a second embodiment
  • Fig. 3 shows a schematic arrangement of a dynamic application with parallel orientation of segments according to a third embodiment
  • Fig. 4 shows a schematic arrangement of a dynamic application with altering radial and tangential orientation of segments according to a fourth embodiment
  • Fig. 5 shows a schematic arrangement of a dynamic application for generating anti-parallel polarized beams according to a fifth embodiment.
  • oriented luminescent materials - of crystalline or ceramic nature - that are pumped by a laser source are used. They generate a polarized beam at a wavelength different from the exciting laser wavelength.
  • projection systems e.g. LCD- and LCoS-projection systems
  • LCD- and LCoS-projection systems can be drastically simplified, since by using a setup like the proposed one, costly elements for polarization control can be omitted.
  • Fig. 1 shows a schematic setup of a light source for generating a polarized light beam with high luminance according to a first embodiment.
  • a focussed laser beam 10 (pump radiation) is directed onto a piece of oriented crystalline or ceramic luminescent material 40 through a beam splitter 20 and illuminates the piece of luminescent material 40 from one side.
  • the converted luminescent radiation 12 is collected from the same side by a reflector 30 (which is not restricted to the shape shown in Fig. 1) and a heat sink 50 is used to removes the heat generated in the luminescent material 40 from the other side.
  • the beam splitter 20 provides a high transmission for the pump radiation of the focussed laser beam 10 from one side and a high reflection for the concerted luminescent radiation 12 from the other side.
  • the proper orientation of the polarization of the converted radiation 12 can be set by rotating the converting element (i.e. oriented luminescent material 40) with respect to the display (not shown) and pumping laser (not shown).
  • the converting oriented luminescent material 40 is fixed in position and the first embodiment is therefore called a static solution or application as opposed to the dynamic solution or application explained in the following embodiments.
  • the static solution is quite suitable for lower power setups, where heat removal can be done via the heat sink 50 shown in Fig. 1.
  • the heat sink 50 may be physically designed to increase the surface area in contact with the cooling fluid surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the design factors which influence the thermal resistance, i.e. thermal performance, of the heat sink 50.
  • Thermal adhesive may be added to the base of the heatsink 50 to help its thermal performance.
  • the heat sink 50 may be made of aluminum, copper, synthetic diamond, or composite materials, for example.
  • the beam splitter 20 may be based on a prism or a mirror.
  • a half-silvered mirror may be used, which is a plate of glass with a thin coating of aluminium with the thickness of the aluminium coating such that part, typically half, of light incident at a 45 -degree angle is transmitted, and the remainder reflected.
  • a dielectric optical coating may be used.
  • reflection/transmission ratios may differ in function of the wavelength. For higher powers and lumen levels, a so-called dynamic solution might be preferred.
  • the heat sink is arranged as a moving element on which a plurality of conversion elements are arrranged so that the focussed light beam selectively illuminates the conversion elements when the moving element moves. This improves heat dissipation.
  • Fig. 2 shows a schematic arrangement of a dynamic application with tangential and radial alignment of conversion segments or conversion elements 42, 44 according to a second embodiment.
  • the converting elements 42, 44 of oriented luminescent material are placed on a spinning wheel 50 having a heat sink function and optionally being made of a heat sink material and/or structure. In this way, the heat generated in the converting elements 42, 44 is spread over the wheel 50 and the average temperature of the converting element can be kept low. Even for dynamic solutions, like color wheels, the converting elements 42, 44 of oriented material segments can be used.
  • the converting elements 42, 44 are attached to the wheel 50 in a proper way to emit a polarized beam. As can be gathered from Fig.
  • the alignment of the orientation of the luminescent material of the converting segments 42, 44 can be arranged radially (right part of Fig. 2) or tangentially (left part of Fig. 2) on the wheel 50.
  • the spot size of a pumping beam 10 should match the size of the converting segments 42, 44.
  • a polarized beam with constant amplitude can be realized based on the excited converted radiation.
  • different elements for the generation of different primary colours can be placed on the wheel 50. Both solutions are well-suited for LCD projection applications because the converted polarized beam can be coupled into a combiner without the need of any polarizer enabling higher brightness and lower cost. Even with a colour wheel the LCD technology can be used to save the polarizer and thus achieve higher brightness.
  • Fig. 3 shows a schematic arrangement of another dynamic application with parallel orientation of conversion elements 46, 48 according to a third embodiment.
  • the conversion elements 42, 44 on the wheel 50 are made out of one piece, or of several single elements arranged with parallel orientation (horizontal orientation in left part of Fig. 3 and vertical polarization on the right part of Fig. 3)
  • the response will be a beam of light with an oscillatory polarization, but constant intensity.
  • This beam can be split into two beams with perpendicular polarization to each other.
  • Such a light source will be very useful to realize a simplified and highly efficient light source for 3D stereoscopic projection systems.
  • the polarization of the two beams alternates with time, along the spinning of the wheel 50.
  • circularly polarised light can be realized very easily by using a lambda/4-retarder though ghosting effects will not be observed any more.
  • Fig. 4 shows a schematic arrangement of a dynamic application with altering radial and tangential orientation of conversion elements 42, 44 according to a fourth embodiment.
  • the conversion elements 42, 44 on the wheel 50 are arranged with alternating radial and tangential orientation a beam with digitally alternating polarization can be realized, where the polarization directly switches between vertical and horizontal polarization.
  • two frames with perpendicular polarization to each other can be projected simultaneously.
  • Such a light source can be very useful to realize a simplified and highly efficient light source for 3D stereoscopic projection systems.
  • Fig. 5 shows a schematic arrangement of a dynamic application for generating parallel and orthogonal polarized beams according to a fifth embodiment.
  • a side view of the rotaing wheel 50 of the schematic arrangement of the fifth embodiment is shown in the left part of Fig. 5 and a diagram with signal waveforms of the normalized intensity i n of the converted output beams with parallel (p) and orthogonal (o) polarization after respective beam splitters 22 and 24 is shown in the right part of Fig. 5.
  • the excitation beam is directed onto conversion elements (not shown in Fig. 5) of radially or tangentially oriented luminescent material provided on a rotating wheel 50.
  • conversion elements not shown in Fig. 5
  • the wheel 50 rotates the polarization of the excited converted radiation continuously changes its orientation in a sinusoidal or oscillating manner.
  • a first beam splitter 20 splits the converted radiation 12 into the upper direction of Fig. 5 towards second and third beam splitters 22, 24.
  • orthogonally polarized radiation is split to obtain a first converted output beam 14 with orthogonal polarization while parallelly or vertically oriented radiation is transmitted through said second beam splitter 22 and enters the third beam splitter 24 where it is split to obtain a second converted output beam 16 with parallel polarization.
  • both output beams 14 and 16 have an oscillating or sinusoidal intensity of opposite polarity due to the oscillating or sinusoidal polarity of the converted radiation 12 generated by the conversion elements.
  • Another example uses infrared laser radiation at about 980nm wavelength and excites, e.g., sodium yttrium fluoride doped with rare earth materials (Erbium (Er), Ytterbium (Yb)), i.e., Er,Yb:NaYF 4 .
  • This material can emit at green and red wavelengths and can also be produced as a single crystal or an oriented ceramic.
  • Suitable materials are for example Pr:YLF, Nd:YLF, Ho:YLF, Yb:NaYF 4 , Yb:Er:NaYF 4 , Ho:NaYF 4 , Tm:Er:NaYF 4 ,
  • Pr,Yb:BaY 2 F 8 Pr:SrAli 2 0i 9 .
  • oriented ceramics or crystals are used as luminescent converters to generate polarized light for projection applications. They can be used as luminescent convertes in static applications or in dynmaic applications (e.g. by using a (colour) wheel with tangential or radial alignment). If a colour wheel with parallel alignment of the converter orientation or with alternating 90° orientation is used, polarized light for 3D stereoscopic projection technology can be generated.
  • the converting elements can be used in reflection or in transparent mode, which means that the converted radiation is obtained with or without reflection at the converting elements.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Polarising Elements (AREA)

Abstract

La présente invention concerne un procédé de production de lumière polarisée et une source lumineuse utilisant une matière céramique ou cristalline orientée pompée par diode laser, au lieu de matières luminescentes ou céramiques non orientées pour produire des faisceaux polarisés. La source lumineuse comportant des matières convertisseuses cristallines ou céramiques orientées qui émettent de la lumière polarisée convient pour une projection numérique à affichage à cristaux liquides standard ainsi que pour une projection 3D stéréoscopique à polarisation.
PCT/IB2012/055500 2011-10-17 2012-10-11 Source de lumière polarisée à luminance élevée WO2013057636A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201161548039P 2011-10-17 2011-10-17
US61/548,039 2011-10-17
US201161549277P 2011-10-20 2011-10-20
US61/549,277 2011-10-20

Publications (1)

Publication Number Publication Date
WO2013057636A1 true WO2013057636A1 (fr) 2013-04-25

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WO (1) WO2013057636A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108248026A (zh) * 2018-01-30 2018-07-06 深圳升华三维科技有限公司 投影式激光加热系统和3d打印机

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US20050041163A1 (en) * 2003-05-07 2005-02-24 Bernie Butler-Smith Stereoscopic television signal processing method, transmission system and viewer enhancements
WO2007084111A2 (fr) * 2005-01-12 2007-07-26 Raytheon Company Laser a semi-conducteurs a haute energie avec pompage deporte et geometrie d'extraction
US20080043788A1 (en) * 2006-06-29 2008-02-21 Tsuyoshi Suzudo Laser-diode pumped solid-state laser apparatus, optical scanning apparatus, image forming apparatus and display apparatus

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US20050041163A1 (en) * 2003-05-07 2005-02-24 Bernie Butler-Smith Stereoscopic television signal processing method, transmission system and viewer enhancements
WO2007084111A2 (fr) * 2005-01-12 2007-07-26 Raytheon Company Laser a semi-conducteurs a haute energie avec pompage deporte et geometrie d'extraction
US20080043788A1 (en) * 2006-06-29 2008-02-21 Tsuyoshi Suzudo Laser-diode pumped solid-state laser apparatus, optical scanning apparatus, image forming apparatus and display apparatus

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108248026A (zh) * 2018-01-30 2018-07-06 深圳升华三维科技有限公司 投影式激光加热系统和3d打印机
WO2019148653A1 (fr) * 2018-01-30 2019-08-08 深圳升华三维科技有限公司 Système de chauffage laser de projection et imprimante 3d
CN108248026B (zh) * 2018-01-30 2020-06-05 深圳升华三维科技有限公司 投影式激光加热系统和3d打印机

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