There is provided an optical system, including a light-transmitting substrate having at least two major surfaces parallel to each other and edges, and an optical device for coupling light into the substrate by total internal reflection. The device includes a polarization sensitive reflecting surface.

Polarizing optical system

Spatial light modulator (SLM) is a general term describing devices that are used to modulate amplitude, phase, or polarization of light waves in space and time. Current SLM–based systems use either optical MEMS (microelectromechanical system, [1]) or LCD technology [2]. In this chapter, we review trends and applications of SLMs with focus on liquid crystal on silicon (LCOS) technology. Most developments of liquid crystal (LC) microdisplays are driven by consumer electronics industry for rear–projection TVs, front projectors, and picoprojectors. Also,MEMS technologies such as digitalmicromirror device (DMD, [3]) and grating light valve (GLV, [4]) are driven by these industries, except for membrane mirrors. Some industrial applications have forced MEMS development for scanning, printing technologies, and automotive applications [5]. But the major R&D-related driving force for new SLM technologies is the defense industry. Technological advances in lithography are the basis for MEMS developments. Phase modulators based on 2D pistonlike mirror arrays [6, 7] or ribbonlike 1D gratings [8] show high performance in frame rate. Unfortunately, the availability of these technologies is limited because they are developed either company-internal or within defence projects. The major advantages of MEMS are frame rate, spectral range, and an efficient use of nonpolarized light. Phase modulators and other optical implementations are still niche markets for the MEMS industry. Even now, customized MEMS developments are quite challenging and expensive. LC panels still have an advantage out of their projection applications in terms of resolution and minimal pixel size for 2D displays. Only LC-based technology is able to modulate intensity, phase, and/or polarization because of polarization rotation and/or electrically controlled birefringence (ECB). LCOS technology [9] was developed for frontand rear(RPTV) projection systems competing with AMLCD (active matrix LCD) and DMD. The reflective arrangement due to silicon backplane allows putting a high number of pixels in a small panel, keeping the fill factor ratio high even for micrometer-sized pixels.

/pdf/1-lcos-spatial-light-modulators-trends-and-applications-cyo2jygg5z.pdf

1 LCOS Spatial Light Modulators: Trends and Applications

A display filter capable of enhancing the visible light transmittance and contrast ratio for a bright room condition and a display device including the same. The display filter includes a filter base, and an external light-shielding layer, disposed on a surface of the filter base, including a matrix made of a transparent resin and a plurality of wedge-shaped black stripes arranged parallel to each other at a surface of the matrix.

Display filter and display device including the same

Techniques, apparatus and systems that use an optical probe head to deliver light to a target and to collect light from the target for imaging, monitoring, medical diagnostics and medical treatment applications.

Delivering Light Via Optical Waveguide and Multi-View Optical Probe Head

A projection display system includes a light source emitting a randomly polarized light and a polarization recapture system including a tunnel integrator and a transmitting/reflecting polarizer coupled to the output end of the tunnel integrator. The input end of the tunnel integrator includes an input aperture and a reflective inside surface coated with a quarter wave retarder. In operation, the randomly polarized light enters the tunnel integrator through the input aperture. The polarization recapture system transmits light having a first polarization as polarized light output and recycles light having a second polarization orthogonal to the first polarization. The light having the second polarization is reflected by the transmitting/reflecting polarizer back into the tunnel integrator. The polarization recapture system recycles the light having the second polarization by reflecting and reorienting the light having the second polarization to light of the first polarization.

Polarization recapture system for liquid crystal-based data projectors

The present invention relates to trim retarders used to compensate for residual birefringence created by liquid crystal display panels. In particular the present invention relates to a trim retarder with negative out-of-plane birefringence provided by a form birefringent multi-layer dielectric stack for compensating for retardances resulting from liquid crystal on silicon display panels.

Trim retarders incorporating negative birefringence

A integrating light pipe re-circulates color to improve efficiency. A number of color filters, such as blue, green, and red filters, on the end of the light pipe transmit a selected color and reflect the remaining light back into the light pipe, where it is spatially homogenized and re-circulated back to the output of the light pipe. The re-circulated homogenized light illuminates the filters, and the process repeats. Thus, most of the light from the light source eventually is transmitted through one of the color filters. The filters can provide straight boundaries between the resultant color beams, which are provided to a scrolling element, such as a rotating prism, rotating mirror drum, or linear oscillating optical element, and hence to a light valve. The combination of the re-circulating light pipe and scrolling element provide continuous color scrolling and efficient use of the broad-spectrum light from the light source.

Scrolling color projection system

A recirculating light polarizer utilizes a reflective polarizer on the exit face of a light integrator, such as a light pipe or light tunnel. Light is provided to the light integrator and light of one polarization is transmitted through the polarizer, the remaining light being reflected back into the integrator. The back-reflected light accumulates polarization shift before it eventually is reflected back to the polarizer. The reflected light is further homogenized on its trip back to the polarizer. This process is typically repeated several times to enhance the light output from the light pipe assembly, with some light being lost in each cycle due to various loss mechanisms. A polarization state modifier, such as a retarder plate or phase-shifting coatings, may be included in the recirculating light path to enhance polarization shift.

Polarizing light pipe

We describe the design and contrast measurement results of a high performance contrast enhancer for an LCoS-based projection display that has these attributes: complete a/c-plate compensation, accurate retardance targeting, excellent retardance magnitude and axis uniformity and environmentally durable. An overall system contrast of more than 4500:1 under f/2.4 cone illumination has been obtained.

64.2: Design and Characterization of a Compensator for High Contrast LCoS Projection Systems

A polarizing conversion system uses a polarizing beam splitter and reflector with a polarization conversion element to convert light from a lamp to a selected polarization state before providing the light to a light integrator, such as a light pipe or light tunnel. The light integrator provides homogenized polarized light to a light modulator. The polarization conversion system avoids increases efficiency compared to absorptive or simple reflective polarizers with fewer components than polarization conversion systems using patterned retarder plates and lenslet arrays. In one embodiment, the conversion elements are held to avoid adhesive or other bonds in the optical path. In other embodiments, high-temperature optical adhesive or optical contact bonding is used to assemble optical components for high-temperature operation. In a particular embodiment, a single-crystal quartz retarder plate is thermally matched to glass components in the polarization conversion system.

Markus Duelli

Papers

Trim retarders incorporating negative birefringence

Scrolling color projection system

Polarizing light pipe

64.2: Design and Characterization of a Compensator for High Contrast LCoS Projection Systems

Polarization conversion light integrator