NEWS FROM AUSA
26 Feb 09. Intevac showed off its advanced range of digital optical sensors at AUSA. Intevac’s sensor business evolved from prior experience manufacturing military night vision devices and knowledge of thin-film processing. The company has expertise in the development of low light level imaging detectors, which are exceptionally sensitive in the visible and near infrared (IR) spectrum. Intevac is currently developing advance electro-optical devices and digital image intensifiers (DI2) for both military and commercial applications. The core imaging sensor is an electron bombarded CMOS sensor, which is based on use of a GaAs photocathode derived from Generation-III image intensifier technology in proximity focus with a high resolution, backside-thinned, CMOS imager anode. The electrons emitted by the photocathode are directly injected in the electron bombarded mode into the CMOS anode. In this approach low noise gain is achieved in the CMOS anode via conversion of the high energy photoelectron (1 – 2 KeV resulting from the high voltage bias applied between the photocathode and CMOS anode) to electron-hole pairs in the anode via the Electron Bombarded Semiconductor (EBS) gain process. The electrons are collected in the APS pixel and subsequently read out. The EBS gain process is inherently low noise with an excess noise factor (Kf) of less than 1.1. This is substantially less than a microchannel plate based Gen-III image intensifier (MCP, Kf of 1.8) or the avalanche gain process in an Electron Multiplying CCD (EMCCD, Kf of 1.4). The low noise EBS gain process eliminates the need for an MCP and enables higher SNR at the lowest light levels. This offers the possibility of higher performance for an EBAPS® based camera relative to a standard Image Intensified camera based on Gen-III tube technology using an MCP for gain or EMCCD based cameras. Intevac’s EBAPS® sensors can be made with different III-V semiconductor photocathodes and CMOS anodes to specifically tailor them for a variety of product applications.
LIVAR® or “Laser Illuminated Viewing and Ranging,” cameras and systems are developed by Intevac under contract with the U.S. Military as a cost-effective solution to a host of long-range targeting and identification requirements. It is a range-gated, laser-illuminated, two-dimensional imaging system that operates in an “eye-safe” wavelength.
While laser imaging has been used in limited applications, previous systems operated in infrared (IR) wavelengths that put both observed and friendly forces at risk of severe optical damage (blinding). This danger resulted in a general ban on the use of the technique. However, with Intevac’s development of the Transferred Electron (TE) photocathode, a high-performance imaging sensor with the desired “single photon level” sensitivity in the eye-safe band became a reality.
Working on internal and Government funding from the Air Force, Army and DARPA, Intevac combined its TE photocathode with an electron-bombarded silicon imager technology to yield a small imaging sensor that could be retrofitted into existing Forward Looking Infrared equipped sights or added easily to new systems. LIVAR can be used as an effective complement to Forward Looking Infrared at ranges where targets can be detected by Forward Looking Infrared, but not recognized. In this role, LIVAR delivers the resolution to identify the detected targets at ranges extending well beyond the identification range capabilities of currently fielded infrared cameras. Lintevec told BATTLESPACE that it was working under a DARPA contract with DRS to build an advanced digital infantry scope.