9.2: Skew Ray Compensated Color Separation Prism for Projection Display Applications

Greenberg, Michael; Bryars, Brett

doi:10.1889/1.1833098

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…2 A Philips prism (of the type found in early threecolor TV cameras) was used for the color management but proved unsuccessful due to polarization mixing at oblique "skew" incident angles. 3 A more successful attempt separates color first, such that a single primary-color beam is directed onto and away from its modulating panel before its recombination and projection. Input beams are thus separately incident upon each panel, allowing near-equivalent architectures to the established transmissive LC system 4 to be adopted.…”

Section: Introductionmentioning

confidence: 99%

Three-panel LCOS projection systems

Robinson¹,

Chen²,

Sharp³

2006

J. Soc. Inf. Display

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-Three-panel liquid-crystal-on-silicon (LCOS) projection systems are presented with an emphasis on the commercially successful shared retarder-stack-filter (RSF) polarizing-beam-splitter (PBS) architectures. The design and operation of the specific CQ90 projection core is presented in detail, and its contrast and transmission derived. alternative three-PBS/X-cube LCOS architectures are briefly introduced and their performance is compared to that of the CQ90.Keywords -Liquid crystal on silicon, rear-projection television, ColorQuad, ColorSelect, retarder stack polarization optical filter. IntroductionLiquid-crystal-on-silicon (LCOS) microdisplay technology offers the greatest performance/cost ratio of all display technologies by combining the high resolution and performance of silicon VLSI with controlled liquid-crystal optical modulation. To view directly in the form of a conventional TV-like display, one or more LCOS display panels need to be projected onto a viewable screen, as shown in Fig. 1. 1 LCOS projection is non-trivial since the panels are reflective. Modulated light forms a reflected beam with a spatially varying polarization state, which occupies the same region of space as the uniform input illuminating light. Physically separating these beams while maintaining good polarization integrity required for high contrast is demanding, particularly in multiple-panel systems where color separation is also necessary. One of the first attempts at three-panel LCOS projection used a polarizing beam splitter (PBS) to separate input and output light prior to RGB color separation and recombination. 2 A Philips prism (of the type found in early threecolor TV cameras) was used for the color management but proved unsuccessful due to polarization mixing at oblique "skew" incident angles. 3 A more successful attempt separates color first, such that a single primary-color beam is directed onto and away from its modulating panel before its recombination and projection. Input beams are thus separately incident upon each panel, allowing near-equivalent architectures to the established transmissive LC system 4 to be adopted. This generic approach uses dichroic plates to separate color within the illumination before utilizing PBSs to direct light onto and away from the panels. Recombination of the imaged light is carried out with an X-cube. A variation on this approach uses angular separation of the input and output beams in an off-axis configuration. 5 This last approach has, to date, suffered from low contrast and difficulties with the registration of the individual panel images, making it less mainstream and will not be discussed further here. Of the generic 3xPBS/X-cube on-axis architectures, there are three distinct types differing in the type of PBS used. Conventional systems use MacNeille-type PBS cubes, whereas more recent systems use either wire-grid PBS plates 6 or embedded reflective polarizing films. 7 The former modified PBS system is often termed Ultrex after developments by ADO, 6 whereas the latter i...

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Section: Introductionmentioning

confidence: 99%

Three-panel LCOS projection systems

Robinson¹,

Chen²,

Sharp³

2006

J. Soc. Inf. Display

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“…Opportunities to improve the contrast of the Philips Prism architecture have been reviewed by Rosenbluth et al 4 and Greenburg et al 5 Theoretical limiting contrasts of 1000:1 have been reported. No products using this type of design are currently known.…”

Section: Discussionmentioning

confidence: 99%

Front‐projection optical‐system design for reflective LCoS technology

Bone¹

2001

J Soc Info Display

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Abstract— Optical designs for three‐panel LCoS projection systems are reviewed. The impact of polarization aberrations in prism‐based systems is discussed and a simple model to analyze the sensitivity of contrast to thermal gradients in prisms is presented. To eliminate stress birefringence in LCoS projection systems, we have developed a projection optical system that does not require the use of polarizing prisms. An improved off‐axis design has been designed that simplifies manufacture and reduces cost. The performance of systems based on this architecture will be discussed.

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“…Electrically switchable color selection structures are another idea used to optimize color in image capture systems [5], and in colorsequential micro-display applications [6]. Projection display systems have implemented a number of color separation elements, which include diffraction gratings [7] and prism-based solutions [8]. Layet and co-workers used gratings and microlens to separate light into an array of red, green, and blue stripes and also showed their maximum theoretical efficiency could be as high as 80%, compared to 30% with color pigments [3].…”

Section: Introductionmentioning

confidence: 99%

P-133: Color Separation Element with Concentric Symmetry for Display Application

Gorkhali

Crawford

2006

SID Symposium Digest

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We report on the design, fabrication, and potential application of electrically switchable quasi‐crystal diffractive elements using a multi‐beam holo‐lithgraphy exposure technique. These quasi‐crystal gratings diffract light in the radial direction with concentric symmetry, serving as efficient color separation elements for potential use in display applications. In addition, we report the fabrication of quasi‐crystals using a holographic method and their electro‐optical properties.

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9.2: Skew Ray Compensated Color Separation Prism for Projection Display Applications

Cited by 6 publications

References 3 publications

Three-panel LCOS projection systems

Three-panel LCOS projection systems

Front‐projection optical‐system design for reflective LCoS technology

P-133: Color Separation Element with Concentric Symmetry for Display Application

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