US Government As Represented by the Secretary of the Army

Other

The United States of America As Represented by the Department of Health

Byong H Ahn

Gary L Wood

Edward J Sharp

William W Clark, Iii

The present invention provides a protective device for sensitive infrared sensors as Forward Looking Infrared imagers (FLIRs). A prior device using materials with higher order susceptibilities to electric polarization, which provides protection against extremely intense radiation from high-power lasers is combined with a low energy optical power limiters such as the chalcogenide glass and the vanadium dioxide which respond reversibly to infrared radiation.

Optical power switch

Two embodiments of a multilayered low energy optical power limiter device are disclosed which protect thermal sensors against laser threats in the far infrared spectral region. One limiter device has multiple layers in order from the incoming radiation side an antireflective coating layer, a window substrate layer, a layer of chalcogenide, a germanium substrate layer, a layer of vanadium dioxide (VO), a window substrate, and an antireflective coating layer. As incoming radiation energy increases, the VOlayer will heat up and change from an unswitched transmissive state to a switched reflective state. The excessive energy past the switched state is reflected back through the germanium and chalcogenide layer and is absorbed quickly therein so that these layers also heat up quickly and are switched almost simultaneously with the VOlayer to provide high optical density at a low switching threshold temperature with high damage threshold. The second embodiment further adds a second VOlayer between the input antireflective coating layer and window substrate layers to reflect high radiation energy immediately.

Far infrared tandem low energy optical power limiter device

A trilaminar semiconductor device is placed at an intermediate focus is an optical instrument having a sensitive photodetector. The layers of the device are successively in the form of a two-photon absorber, a sacrificial layer, and a multiple quantum well. The composition of the semiconductor is varied in the layers to achieve the desired bandgap and function.

Broadband protector for photodetectors

The Laser Line Identifier (LLI) is a real-time device which can indicate wavelengths of the laser radiations. LLI mainly consists of a beam splitter, narrow bandwidth transmission filters and detectors. The filters and the detectors form a unique pair so that a signal detected at a particular detector can only mean the radiation of a certain wavelength. The detectors are hardwired to a set of indicators such as a set of colored lights or a voice recording so that the wavelength of the radiation is clearly indicated even to a non-technical person.

Growing community of inventors

Springfield, VA, United States of America

Byong H Ahn