Abstract: An apparatus is disclosed for filtering of probe light. The apparatus includes an optical filter comprised of a medium circular birefringence between crossed polarizers. The circular birefringent medium changes the polarization of light of a particular frequency bandwidth. So that after passing through the first polarizer, the polarization of a particular frequency bandwidth probe light is rotated between crossed polarizers so it will be transmitted through the second polarizer. The birefringent medium is constructed from a gaseous substance such as atomic vapor and two pump lasers in resonance with absorption lines of the absorbing substance by the process of two-photon absorption. A magnetic field is utilized in some embodiments that permeates the absorbing substance and separates absorption lines for excited state transitions by the Zeeman effect.

Abstract: A photon collimator, suitable for use in medical imaging equipment, is constructed from a block of photon-attenuating material, such as solid tungsten or molybdenum alloy that defines a plurality of integrally formed septa slats. Each slat has an elongated length dimension greater than thickness and depth dimensions, and is oriented in an opposed pattern array that is laterally spaced relative to its respective thickness dimension. An aperture channel is defined between each pair of opposed slats. Rows of integrally formed slats in one block or separately affixed blocks may be stacked on each other at skewed angles to form two-dimensional grids of apertures having polygonal cross sections. The slats may be formed by electric discharge or laser thermal ablation machining, such as by a sequential passing of an EDM wire cutting head along the pattern array, repeating sequential cutting of respective channel depth and width.

Abstract: An illumination system and a projection device comprising the same are provided. The projection device further comprises an imaging system. The illumination system comprises a first light source, a dichroic element and a wheel plate. The dichroic element comprises a first dichroic portion and a second dichroic portion. The first light source provides a first wave band light, which is reflected to the wheel plate by the first dichroic portion. When being projected onto a wave band transforming area of the wheel plate, the first wave band light will be transformed into a second wave band light by the wave band transforming area and then emits through the first dichroic portion and the second dichroic portion. When being projected onto a reflecting area of the wheel plate, the first wave band light will be reflected by the reflecting area to emit through the second dichroic portion.

Abstract: A grating has a high diffraction efficiency into the minus first diffracted order in transmission, for both TE and TM polarizations. The incident angle may optionally be chosen so that the minus first diffracted order in reflection would be retroreflected back to the incident beam. The grating may be formed from various materials and/or layers, where the thicknesses of the individual layers may be determined by an optimization or simulation process. In one aspect, the grating may have four or more layers, formed with three or more materials. In another aspect, the grating may have a longitudinal refractive index profile that contains at least two local extrema, such as a maximum and/or minimum. Such a grating may be formed from three or more materials, two materials, or a single material that has a continuously varying refractive index. Any or all of the materials may have a continuously varying refractive index profile, as well.