Abstract: A beam splitter optical surface comprises a transparent substrate and a multilayer optical coating applied in a pattern onto the transparent substrate. The multilayer optical coating has at least an optically reflective layer and an optically absorbent layer.

Abstract: A thermal imager comprises a thermal video detector for detecting thermal video images and generating a video signal representing those thermal video images. Often, imaging optics are used for imaging light onto the thermal video detector. A display mode selector is also provided for enabling a selection between different video display modes. A video controller then scales the video signal in response to the display mode of the selector for display on a visible video display, which receives the scaled video signal from the video controller and displays the thermal video images. In the typical application, the display mode selector is operated by a user to select between a hand-held mode or mode in which the imager is used with a non-magnifying gun weapon sight, on one hand, and a mode for use with a magnifying telescopic sight of a weapon, on the other. In these latter applications, possibly only a portion of output of the video display is imaged through the telescopic sight of the weapon.

Abstract: An optical device comprises a dichroic beamsplitter for splitting an object beam into a reflected beam having a first waveband and a transmitted beam having a second waveband; an astigmatism-correcting lens element, disposed in the optical path of the transmitted beam; and a coma-correcting lens element, disposed in the optical path of the transmitted beam.

Abstract: An optical device comprises a dichroic beamsplitter for splitting an object beam into a reflected beam having a first waveband and a transmitted beam having a second waveband; an astigmatism-correcting lens element, disposed in the optical path of the transmitted beam; and a coma-correcting lens element, disposed in the optical path of the transmitted beam.