WO2012100298A1 - Moteur optique laser comprenant des moyens pour supprimer le speckle du laser - Google Patents

Moteur optique laser comprenant des moyens pour supprimer le speckle du laser Download PDF

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Publication number
WO2012100298A1
WO2012100298A1 PCT/AU2012/000063 AU2012000063W WO2012100298A1 WO 2012100298 A1 WO2012100298 A1 WO 2012100298A1 AU 2012000063 W AU2012000063 W AU 2012000063W WO 2012100298 A1 WO2012100298 A1 WO 2012100298A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical engine
laser
light
laser optical
speckle
Prior art date
Application number
PCT/AU2012/000063
Other languages
English (en)
Inventor
Danny Jung
Peter Rubinshtein
Original Assignee
Digislide Holdings Limited
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
Priority claimed from AU2011900267A external-priority patent/AU2011900267A0/en
Application filed by Digislide Holdings Limited filed Critical Digislide Holdings Limited
Publication of WO2012100298A1 publication Critical patent/WO2012100298A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/3173—Constructional details thereof wherein the projection device is specially adapted for enhanced portability
    • 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
    • G02B27/48—Laser speckle optics
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/208—Homogenising, shaping of the illumination light
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
    • H04N9/3111—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3161—Modulator illumination systems using laser light sources
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3164—Modulator illumination systems using multiple light sources

Definitions

  • Laser optical engine with means to remove laser speckle
  • the present invention relates to an optical engine consisting of an LCOS (Liquid crystal on silicon) panel using multiple lasers to illuminate the panel, a projection lens then relaying the image onto a surface, the optical engine minimizing laser speckle.
  • LCOS Liquid crystal on silicon
  • the lasers are already polarised and as the LCOS requires polarised light, lasers are a more efficient light source.
  • the lasers beams have practically collimated shapes which makes
  • the contrast of the projected image can be higher than a design using large cone angles. 3.
  • the small cone angles allows for a simpler lens design resulting in a smaller package.
  • Speckle has been, and is, the chief limitation of coherent imaging. An image with a speckle problem will have the visual effect of a boiling liquid or of a television set that is way out of tune.
  • a speckle pattern is a random intensity pattern produced by the mutual interference of a set of wavefronts. This phenomenon has been known and the subject of investigation by scientists for hundreds of years. The issue of speckles however, has become a focus in recent times because of the increase in the use of lasers, and the variety of applications thereof.
  • the speckle pattern is random, particularly if the laser beam is scattered off a rough surface. Likewise, when the laser is beamed through imperfect optics, or through the atmosphere, speckle forms, which if highly magnified appears like the image of a star.
  • Speckle is a problem in laser based display systems like the Laser TV. Speckle is usually quantified by the speckle contrast. Speckle contrast reduction is essentially the creation of many independent speckle patterns, so that they average out on the retina/detector. This can be achieved by several methods.
  • Wavelength diversity using multiple laser sources with differing wavelengths. 4. Scanning lasers, such as the MEMS system (as above)
  • speckle reduction in coherent optical imaging include rotating diffusers which interfere with the spatial coherence of the laser light, synthetic array heterodyne detection, use of spatial filters and optical heterodyn detection - when signal frequencies are non-linearly mixed with a local oscillator set at a close-by frequency, resulting in a different frequency, which carries amplitude, phase, and frequency modulatioii of the original higher frequency signal, but which is oscillating at a lower frequency.
  • the eye is particularly vulnerable to lasers because the radiation is emitted in a well-collimated beam. If a laser beam intersects the eye, radiation is transmitted through the cornea, aqueous humor, lens and vitreous humor and is imaged or focused to a small area on the retina, causing tissue necrosis resulting in visual impairment. The severity of the injury will be dependent on the exposure dose.
  • Lasers emitting wavelengths approximately 400 to 1,400 nm are in the "retinal hazard spectral region".
  • the object of this invention is to provide an optical engine that overcomes at least some of the abovementioned problems or provides the public with a useful alternative.
  • a laser optical engine for reducing laser speckle comprising;
  • a green laser adapted to emit a beam of light through a prism and a beam expander
  • said apparatus further including a first lenslet array positioned between the prism and the beam expander, said light passing through the beam expander then passing through a first and then a second dichroic mirror and then through a second lenslet array and through a lens before passing through a polarising beam splitter and reflected in a LCOS panel to then pass through a projection lens and be projected onto a surface.
  • the laser optical further comprises a red and a blue leaser, the light from those lasers entering the optical engine by reflection through respective dichroic mirrors.
  • the lenslet arrays comprise a hexagonal grid.
  • first and second lenslet arrays comprise a square grid of at least 16 lenslets at least partially within the beam.
  • the lenslet arrays comprise fused silica.
  • the beam splitter widens the beam of light thereby dissipating it and reducing its intensity.
  • the lenslet arrays comprise a first side comprising an array of concave cylindrical surfaces.
  • Fig 1 is a schematic drawing illustrating the optical engine.
  • the optical engine described herein may utilize any sized LCOS panel, or similar display panel,, and Red, Green and Blue lasers to illuminate the panel.
  • the initial prototype has used a 0.29" WVGA monochrome LCOS panel.
  • Other prototypes may include a .21 " LCOS panel, SVGA, WVGA or SVGA SIZE. It is however no intended to limit the invention to either the size or resolution of the panel.
  • the projection system may use a hybrid of laser and LED light sources. This is well known in prior art.
  • a projection lens relays the image onto a screen or wall.
  • the three lasers are turned on and off in synchronization with the appropriate Red, Green and Blue image on the LCOS panel to produce full colour images on the screen.
  • the basic principles of colour sequential digital projectors are well known.
  • the advantages and disadvantages of the use of lasers have been noted above. As outlined above the disadvantages of using lasers as light sources are speckle and safety issues.
  • the present invention addresses the above issues, as well as having the potential to lower the cost of manufacture.
  • Green laser Because the Green laser has a narrower beam waist diameter of approximately 50 microns (or maximum of .1 mm) it is more prone to speckling issues. It is also more prone to being a hazard to the human eye. Thus, the following description addressed the issues with the Green laser. However, Red and Blue lasers maybe similarly treated, or may beam directly onto dichroic mirrors. Much depends on the width of the laser beam.
  • the prism is designed with two functions; to slightly expand the beam diameter and to provide some de- speckling properties.
  • the beam then passes through a further beam expander 2B with a lenslet array 3 having a hexagonal shape lenslet.
  • This configuration does three things.
  • the hexagonal lenslet array may also be incorporated into the Red and Blue lasers. As the laser light is made up of a multitude of images from each lenslet the beam intensity is reduced, further reducing eye hazard and further reducing speckle.
  • a Red, Green and Blue laser illuminates a lenslet array 6 with rectangular lenslets of 16:9 aspect ratio via dichroic mirrors 4 and 5.
  • the light from the Red and Blue lasers are collimated using a collimating lens.
  • the light from the Green laser 1, is expanded using a beam expander 2A and 2B, which incorporates a lenslet array 3 with hexagonal shaped lenslets.
  • the 1 :9 ratio matches the aspect ratio of the panel ensuring efficient and uniform illumination, and minimal light loss.
  • a different panel aspect ratio will call for a corresponding aspect ratio on the lenslet array.
  • the beam is widened reducing speckle further reducing the hazard to the human eye of the end consumer.
  • the light emanating from the 16:9 array is relayed through a lens 7 onto the polarising beam splitter 8.
  • the polarising beamsplitter acts as an analyser, allows the light to reflect off the LCOS panel, further reducing the laser hazard.
  • the light reflects onto the LCOS panel 9 which allows the light from "on” pixels to pass to the screen while blocking the "off” pixels to create the image.
  • the image is then passed back through the polarising beamsplitter 8 and out through the projection lens 10 as the full projected image.
  • the design of the prism and the ratio of the lenslet array may be changed under different designs to match a different aspect ratio of a different panel, to ensure efficient and uniform illumination of a different panel.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Projection Apparatus (AREA)
  • Mechanical Optical Scanning Systems (AREA)

Abstract

La présente invention se rapporte à un moteur optique laser adapté pour réduire le speckle du laser. Le moteur selon l'invention comprend, montés en série : un laser vert adapté pour émettre un faisceau de lumière à travers un prisme ; un premier ensemble de petites lentilles ; un dilatateur de faisceau ; un premier miroir dichroïque, suivi d'un second miroir dichroïque ; un second ensemble de petites lentilles ; une lentille ; un séparateur de faisceau polarisant ; un écran LCOS ; et une lentille de projection. Lorsque le moteur optique est utilisé pour projeter l'image telle qu'elle apparaît sur l'écran LCOS, trois lasers sont utilisés. Ces lasers se trouvent dans les parties verte, bleue et rouge du spectre électromagnétique. Les lasers bleu et rouge ne passent pas à travers le dilatateur de faisceau. Au contraire, ils sont introduits dans le moteur optique via la réflexion produite à travers leurs miroirs dichroïques respectifs.
PCT/AU2012/000063 2011-01-28 2012-01-27 Moteur optique laser comprenant des moyens pour supprimer le speckle du laser WO2012100298A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2011900267 2011-01-28
AU2011900267A AU2011900267A0 (en) 2011-01-28 Laser optical engine with means to remove laser speckle

Publications (1)

Publication Number Publication Date
WO2012100298A1 true WO2012100298A1 (fr) 2012-08-02

Family

ID=46580124

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2012/000063 WO2012100298A1 (fr) 2011-01-28 2012-01-27 Moteur optique laser comprenant des moyens pour supprimer le speckle du laser

Country Status (1)

Country Link
WO (1) WO2012100298A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081381A (en) * 1998-10-26 2000-06-27 Polametrics, Inc. Apparatus and method for reducing spatial coherence and for improving uniformity of a light beam emitted from a coherent light source
WO2008040529A1 (fr) * 2006-10-07 2008-04-10 Carl Zeiss Ag Dispositif pour réduction du chatoiement
CN101493582A (zh) * 2009-02-23 2009-07-29 福州高意通讯有限公司 一种消激光散斑的光学结构
WO2010023444A1 (fr) * 2008-08-27 2010-03-04 Milan Momcilo Popovich Affichage laser intégrant une réduction de granularité

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081381A (en) * 1998-10-26 2000-06-27 Polametrics, Inc. Apparatus and method for reducing spatial coherence and for improving uniformity of a light beam emitted from a coherent light source
WO2008040529A1 (fr) * 2006-10-07 2008-04-10 Carl Zeiss Ag Dispositif pour réduction du chatoiement
WO2010023444A1 (fr) * 2008-08-27 2010-03-04 Milan Momcilo Popovich Affichage laser intégrant une réduction de granularité
CN101493582A (zh) * 2009-02-23 2009-07-29 福州高意通讯有限公司 一种消激光散斑的光学结构

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