In this paper we are presenting the ELOP concept of the night vision for the modern soldier. According to this
concept the modern soldier's missions are divided into 4 main layers - situation awareness, improved lethality
capabilities, target acquisition and surveillance. Based on this concept during the last few years ELOP has
developed a family of products for those needs. Those new products are mainly based on the uncooled technology
(with one exception). The uncooled technology allows cost eective solution with superior performance in
comparison with image intensiers systems (by means of better robustness to poor lighting conditions, better
immunity to dazzling etc.). Those products include thermal monocular, driver thermal sight, thermal weapon
sights and hand held thermal cameras.
The two-dimensional spatial response of a pixel in SCD's back-side illuminated InSb Focal Plane Array (FPA) is
measured directly for arrays with a small pitch, namely 30, 20 and 15&mgr;m. The characterization method uses a spot-scan
measurement and de-convolution algorithm to obtain the net spatial response of a pixel. Two independent methods are
used to measure the detector spatial response: a) direct spot-scan of a pixel with a focused beam; b) uniform illumination
upon back-side evaporated thin gold coating, in which sub-pixel apertures are distributed in precise positions across the
array. The experimental results are compared to a 3D numerical simulation with excellent agreement for all pitch
dimensions. The spatial response is used to calculate the crosstalk and the Modulation Transfer Function (MTF) of the
pixel. We find that for all three pixel dimensions, the net spatial response width (FWHM) is equal to the pitch, and the
MTF width is inversely proportional to the pitch. Thus, the spatial resolution of the detector improves with decreasing
pixel size as expected. Moreover, for a given optics and smaller array pitch, the overall system spatial resolution is
limited more by the optical diffraction than by the detector. We show actual improved spatial resolution in an imaging system with a detector of smaller array pitch.
We have shown a method of target acquisition with a high Probability of Detection (Pd), extremely low False Alarm Rate (FAR), which can be implemented in real time hardware existing in most of ELOP's FLIRs.
This target acquisition method is based on sensing the linear polarized radiation of the scene and is based on the phenomenon that facets found on most man made targets show a high degree of linear polarization while natural background elements do not. Using this phenomenon (after fixing all the engineering hurdles such as polarizer wobble, etc) can give us a powerful tool for acquiring targets in cluttered backgrounds, where "regular FLIRs", even the most sensitive ones, fail to acquire targets. This phenomenon is most successful where the limiting factor for detection is the clutter, so although lowering scenes SNR (Signal to Noise Ratio), by introducing the polarizer, we get higher SCR (Signal to Clutter Ratio) which is often the real limiting factor in real life. The phenomenon was found to be very robust over different targets and backgrounds in the LWIR and much weaker in the MWIR.
This paper describes a novel design of a 1:30 zoom FLIR in the MWIR. Special emphasis is spent on the design considerations of such a FLIR and on the specific challenges associated with the design of a high zoom ratio FLIR. The problems and their solutions are discussed through out the paper and quantitative results are tested.