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

An elongated LED lighting arrangement comprises an elongated light pipe with homogeneous optical material between first and second ends. In an exemplary embodiment, an LED provides blue light to the light pipe via a first dichroic mirror tuned to pass blue light. Down-converting means on sidewall of the light pipe, tuned to receive blue light, absorbs blue light from the LED and to emit lower-energy light outside of the light pipe at respectively higher wavelengths. Light-extracting means on the sidewall extract from the light pipe some blue light without changing the wavelengths of the foregoing light. Light from the down-converting means and the light-extracting means are combined to provide a composite color. The first dichroic mirror receives some light emitted by the down-converting means and reflects back into the light pipe more than 80 percent of the light received by the mirror.

Elongated LED lighting arrangement

A polarization based diagnostic device ( 200 ) for optically examining the medical condition of tissue ( 290 ) comprises an illumination optical system ( 205 ), comprising a light source ( 220 ) and beam shaping optics. An optical detection system ( 210 ) comprises imaging optics and an optical detector array, which detects light from the tissue. Polarizing optics provided in both the illumination optical system and the optical detection system are crossed and pass orthogonal polarization states. Iterative rotational means rotate the orthogonal polarization states relative to the tissue being examined. Image enhancement means includes image processing, sequential multi-spectral illumination and imaging, and image focus control to facilitate quality imaging at varying depths within the tissue. A controller ( 215 ) operates the light source, the detector array, the multi-spectral illumination and imaging, image focus control, and image processing.

Wound healing monitoring and treatment

An integrating rod ( 200 ) for use with a multiple segment dynamic filter, such as a spiral dichroic color wheel having three or more narrow filters adjacent to the exit face ( 206 ) to enable the integrating rod to recapture light rejected by a given segment of the dynamic filter. The rejected light travels back through the integrating rod where a majority of the light strikes the mirrored entrance face ( 202 ). Light reflected by the mirrored entrance face, or light exiting through the entrance aperture ( 204 ) and returning to the integrating rod after being reflected by the lamp reflector, once again travels to the exit face ( 206 ) of the integrating rod ( 200 ). After exiting through the exit face ( 206 ) of the integrating rod ( 200 ) a second time, the recycled light has a good chance of striking a different filter segment of the dynamic filter and being used by the display system.

Rod integrators for light recycling

The present invention provides an enhanced polarized light source for a display system. In one embodiment, the invention includes a light source (11) to produce light having multiple polarization states, a relay optical system (23) to relay light imaged onto the relay optical system onto a display (17), an optical imaging element (25) to image light from the light source onto the relay optical system (23), a polarization separator (34) to direct light of a first polarization to a first portion of the optical imaging element and light of a second orthogonal polarization to a second portion of the optical imaging element, and a polarization conversion element (35) between the optical imaging element and the relay optical system to receive light having the second polarization from the optical imaging element and convert its polarization to the second polarization.

Polarized light source system with dual optical paths

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

With the availability of small arc size high intensity discharge lamps a new polarization recovery system using polarization recycling in a light pipe is made possible. Combining light integration/homogenization with polarization recovery in an integrator rod leads to cost reduction and smaller light engines. The polarization recovery light pipe utilizes a reflective polarizer that works at normal incidence at its exit face and a high-reflective mirror with a transparent circular aperture at the entrance face. The reflected linearly polarized light is recycled by rotating its polarization by 90 degree(s) during one round-trip in the integrator rod. Different possibilities for achieving this polarization rotation, including retarders and phase control coatings are investigated. As much as 70% of the rejected polarized light can be recaptured with this system.

Polarization recovery system based on light pipes

intensity discharge lamps with small arc sizes facilitate the design of a new polarization recovery system that doubles as a beam homogenizer. As much as 70% of the rejected polarized light can be recovered and re-emitted in the desired polarization state while eliminating the need for a separate integrator assembly. In this paper we discuss the design and performance of two implementations of this system. 1. Introduction crystal based projection displays require polarized light to operate. Current light engines use either polarizing components, like polarizing beam splitters, and thus lose at least half of the available light or polarization conversion systems to achieve polarized light at the light valve. With the availability of small arc size high intensity discharge lamps a new polarization recovery system using polarization recycling in a light pipe is made possible. Combining light homogenization with polarization recovery in the integrator rod leads to cost reduction and smaller light engines. A similar recovery scheme for colors has recently been reported by DeWald et.al. (1). A schematic of the proposed polarization recovery light pipe is shown in Figure 1. The system consists of a hollow or solid integrator rod, a mirrored input aperture, a reflective polarizer and a quarter wave plate for polarization rotation.

http://otec.inha.ac.kr/pds/dn.php?board=tb_optics_related&sq=239&col=filename1

Clark Pentico

Papers

Polarizing light pipe

Polarization recovery system based on light pipes

36.2: Integrator Rod with Polarization Recycling Functionality