No abstract

We have been actively pursuing the development of long-wavelength infrared (LWIR) HgCdTe grown by molecular beam epitaxy (MBE) on large-area silicon substrates. The current effort is focused on extending HgCdTe/Si technology to longer wavelengths and lower temperatures. The use of Si versus bulk CdZnTe substrates is being pursued due to the inherent advantages of Si, which include available wafer sizes (as large as 300 mm), lower cost (both for the substrates and number of die per wafer), compatibility with semiconductor processing equipment, and the match of the coefficient of thermal expansion with silicon read-out integrated circuit (ROIC). Raytheon has already demonstrated low-defect, high-quality MBE-grown HgCdTe/Si as large as 150 mm in diameter. The focal plane arrays (FPAs) presented in this paper were grown on 100 mm diameter (211)Si substrates in a Riber Epineat system. The basic device structure is an MBE-grown p-on-n heterojunction device. Growth begins with a CdTe/ZnTe buffer layer followed by the HgCdTe active device layers; the entire growth process is performed in situ to maintain clean interfaces between the various layers. In this experiment the cutoff wavelengths were varied from 10.0 lm to 10.7 lm at 78 K. Detectors with >50% quantum efficiency and R 0 A~1000 Ohms cm 2 were obtained, with 256 · 256, 30 lm focal plane arrays from these detectors demonstrating response operabilities >99%.

No abstract

No abstract

Polarimetry sensor development has been in work for some time to determine the best use of polarimetry to differentiate between manmade objects and objects made by nature. Both MWIR and LWIR Focal Plane Arrays (FPAs) have been built at Raytheon Vision Systems each with exceedingly higher extinction ratios. This paper compares field imagery between MWIR and LWIR micro-grid polarimetric sensors independently and during simultaneous image collects.LWIR polarimetry has the largest polarimetric signal level and an emissive polarimetric signature which allows detection at thermal crossover and is less dependent on sun angles. Polished angled glass and metal objects are easily detected using LWIR polarimetry. While LWIR polarimetry has many advantages its resolution is not as good as MWIR.MWIR polarimetry has higher resolution than LWIR. With good sun angles plastic drums, and wet surfaces provide good polarization signatures. With poor sun angles detection can be challenging.To gain acceptance polarimetric sensors must provide intelligence signatures that are better than existing nonpolarimetric Infrared sensors. This paper shows several examples of images without polarimetric processing and identical images with MWIR and/or LWIR polarimetric fusion onto the non-polarized images to show the improvement of detection using polarimetric sensors. It is the author's belief that the fastest way to gain acceptance of polarimetric remote sensing is through field demonstration as shown in Figure 1.