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National Research Council of Canada

Simon Boothroyd

Simon Andrew Boothroyd

Jacek Chrostowski

Jerzy A Dobrowolski

Maurice Stephen O'Sullivan

A polarizing beam splitter has a pair of opposed transparent prism substrates with a refractive index n, and providing at least one input port and at least one output port. The input port accepts light incident over a range of operational angles including a central operational angle. A multilayer thin film structure is sandwiched between the pair of opposed transparent substrates and consists essentially of a plurality of layers l. . . lhaving respective refractive indices n. . . n, wherein at least three of said refractive indices n. . . nare different, and wherein the refractive index of the substrates nlies between the highest refractive index nand lowest refractive index n, and wherein n, nand ndefine a Brewster angle &#x3b8;: a critical angle &#x3b8;: The refractive indices nand n. . . nare selected such that the central operational angle for a beam incident on the multiple thin film structure lies above the Brewster angle &#x3b8;and such that most or all the operational angles defined by said input port lie above the Brewster angle &#x3b8;. For p-polarized light at least one optical admittance of the layers with refractive indices n. . . nis lower or very close to that of the optical admittance of the substrate for the operational angles such that the thin film polarizing beam-splitter favors the transmittance for p-polarized light incident at that input port such that most of the p-polarized light is transmitted through the multiple thin film structure. For s-polarized light the polarizing beam-splitter acts as a high reflective coating to favor the reflectance for s-polarized light incident at the input port such that most of the s-polarized light is reflected from said multiple thin film structure. The polarizing beam splitter is compact and yet remains functional over a wide range of operational angles.

Polarizing beam splitters

A projection apparatus has a first light beam having a first state of polarization and containing a first set of primary colors, a first light modulator arrangement for spatially modulating the polarization state of the first light beam to encode a first image thereon in the first set of primary colors, a second light beam having a second state of polarization and containing a second set of primary colors, and a second light modulator arrangement for spatially modulating the polarization state of the second light beam to encode a second image thereon. A polarizing beam splitter having first and second input ports to admit the first and second encoded light beams. Light of one polarization state incident on the first port is transmitted to the output port and light of another polarization state incident on the second port is reflected to said output port so that said transmitted and reflected light is combined into a common output beam at said output port. The first and second images having different polarizations contained in the output beam projected onto a display screen can be viewed with the aid of glasses with selective color filters responsive to the first and second sets of primary colors. By using different sets of primary colors considerable efficiencies and economies can be realized relative to a pure polarization-based system.

Projection display systems

A dual-mode stereoscopic three-dimensional (3D) projection display with two micro-display panels is provided. In a passive 3D mode, the 3D projection display simultaneously projects left-eye and right-eye images with first and second polarizations on the screen. The first and second polarizations are orthogonal to each other. In a first passive mode, a polarization-preserving screen is used and passive polarizing glasses can be worn to see the 3D images. In a second passive mode, an ordinary screen is used and 3D color filter glasses can be worn to see the 3D images. In an active mode, the display projects left-eye and right-eye images, with both first and second polarizations, time-sequentially and liquid crystal shutter glasses synchronized with the image sources can be worn to see 3D images. The dual-mode 3D projection display can be switched electronically to project 2D images when the same 2D image signals are fed to both micro-display panels. The dual-mode 3D projection display is more light efficient than conventional single panel projection displays because at any given time, at least two primary colors are displayed on screen with orthogonal polarizations.

Dual-mode three-dimensional projection display

An image-combining device comprising of a polarizing beam-splitter, two waveplates and two reflective micro-electro-mechanical display panels is described. It combines images with orthogonally polarized light. Projection display apparatus having such image-combining device(s) are used to project two-dimensional or three-dimensional images with orthogonally polarized light.

Image-combining device and projection display apparatus having image-combining devices incorporated therein

In a Michelson inteferometer with phase conjugate mirrors at least one of such mirrors includes a Kerr medium. This enables control over the relative phases of the beams that are reflected from the mirrors and superimposed to form an output beam. The interferometer can be used to perform a logic function by interposing transparencies in the reflected beams. By appropriate choice of the relative phases a logic OR function can be achieved.

Interferometer

A method of optical phase to amplitude demodulation comprises intersecting two mutually coherent beams of light inside a Kerr medium. One of the beams is unmodulated and the other is phase modulated. The Kerr medium is non-linear and is characterized by an equation n=n.sub.0 +n.sub.2 I, where n is the local refractive index of the medium at a point of interest, n.sub.0 is the linear refractive index of the medium, n.sub.2 is a nonlinear refractive index of the medium and I is the light intensity at the point of interests. An amplitude modulated output beam is generated.

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Ottawa, Canada

Simon Andrew Boothroyd