Over the past few years, a new type of High Operating Temperature (HOT) photon detector has been developed at SCD,
which operates in the blue part of the MWIR window of the atmosphere (3.4-4.2 μm). This window is generally more
transparent than the red part of the MWIR window (4.4-4.9 μm), especially for mid and long range applications. The
detector has an InAsSb active layer, and is based on the new "XBn" device concept. We have analyzed various electrooptical
systems at different atmospheric temperatures, based on XBn-InAsSb operating at 150K and epi-InSb at 95K,
respectively, and find that the typical recognition ranges of both detector technologies are similar. Therefore, for very
many applications there is no disadvantage to using XBn-InAsSb instead of InSb. On the other hand XBn technology
confers many advantages, particularly in low Size, Weight and Power (SWaP) and in the high reliability of the cooler
and Integrated Detector Cooler Assembly (IDCA). In this work we present a new IDCA, designed for 150K operation.
The 15 μm pitch 640×512 digital FPA is housed in a robust, light-weight, miniaturised Dewar, attached to Ricor's
K562S Stirling cycle cooler. The complete IDCA has a diameter of 28 mm, length of 80 mm and weight of < 300 gm.
The total IDCA power consumption is ~ 3W at a 60Hz frame rate, including an external miniature proximity card
attached to the outside of the Dewar. We describe some of the key performance parameters of the new detector,
including its NETD, RNU and operability, pixel cross-talk, and early stage yield results from our production line.
Long range sights and targeting systems require a combination of high spatial resolution, low temporal NETD, and wide
field of view. For practical electro-optical systems it is hard to support these constraints simultaneously. Moreover,
achieving these needs with the relatively low-cost Uncooled μ-Bolometer technology is a major challenge in the design
and implementation of both the bolometer pixel and the Readout Integrated Circuit (ROIC).
In this work we present measured results from a new, large format (1024×768) detector array, with 17μm pitch. This
detector meets the demands of a typical armored vehicle sight with its high resolution and large format, together with
low NETD of better than 35mK (at F/1, 30Hz). We estimate a Recognition Range for a NATO target of better than 4 km
at all relevant atmospheric conditions, which is better than standard 2nd generation scanning array cooled detector. A
new design of the detector package enables improved stability of the Non-Uniformity Correction (NUC) to
environmental temperature drifts.
A new generation of high-performance uncooled detector arrays, with 17 and 25 μm pitch, improved sensitivity, and
extended spectral response were developed recently by SCD. This development brings the uncooled infrared technology
very close to the performance of traditional second generation cooled LWIR detectors, and enables a new range of
applications. We demonstrate the use of our Very High Sensitivity (VHS) 25 μm pitch detector with F/2.4, for long
range observation systems. We also present the new Wide-Band (WB) detector, where the detector absorption is tuned to
both the MWIR and LWIR bands, which is optimal for use in some applications such as situation awareness.
Furthermore, in this work we present our 17 μm pitch new family of detectors with different array formats (QVGA,
VGA and XGA). These detectors are targeting a wide range of applications, from medium-performance with low Size,
Weight and Power (SWaP) applications, up to high-performance imaging applications.
Over the last decade SCD has established a state of the art VOx μ-Bolometer product line. Due to its overall advantages
this technology is penetrating a large range of systems. In addition to a large variety of detectors, SCD has also recently
introduced modular video engines with an open architecture.
In this paper we will describe the versatile applications supported by the products based on 17μm pitch: Low SWaP
short range systems, mid range systems based on VGA arrays and high-end systems that will utilize the XGA format.
These latter systems have the potential to compete with cooled 2nd Gen scanning LWIR arrays, as will be demonstrated
by TRM3 system level calculations.
SCD has recently presented an uncooled detector product line based on the high-end VOx bolometer technology. The first FPA launched, named BIRD - short for Bolometer Infra Red Detector, is a 384x288 (or 320x240) configurable format with 25μm pitch. Typical NETD values for these FPAs range at 50mK with an F/1 aperture and 60 Hz frame rate. These detectors also exhibit a relatively fast thermal time constant of approximately 10 msec, as reported previously.
In this paper, the special features of BIRD optimized for unattended sensor applications are presented and discussed.
Unattended surveillance using sensors on unattended aerial vehicles (UAV's) or micro air vehicles (MAV's) , unattended ground vehicles (UGV's) or unattended ground sensor (UGS) are growing applications for uncooled detectors. This is due to their low power consumption, low weight, negligible acoustic noise and reduced price. On the other hand, uncooled detectors are vulnerable to ambient drift. Even minor temperature fluctuations are manifested as fixed pattern noise (FPN). As a result, frequent, shutter operation must be applied, with the risk of blocking the scenery in critical time frames and loosing information for various scenarios.
In order to increase the time span between shutter operations, SCD has incorporated various features within the FPA and supporting algorithms. This paper will discuss these features and present some illustrative examples.
Minimum power consumption is another critical issue for unattended applications. SCD has addressed this topic by introducing the "Power Save" concept. For very low power applications or for TEC-less (Thermo-Electric-Cooler) applications, the flexible dilution architecture enables the system to operate the detector at a number of formats. This, together with a smooth frame rate and format transition capability turns SCD's uncooled detector to be well suited for unattended applications. These issues will be described in detail as well.
IRISIM is an imaging and video simulation program that models and simulates the entire imaging process of broadband and multispectral infrared imaging systems. IRISIM receives mono- and multi-spectral, high resolution flux images of infrared scenes, processes the imagery as a function of desired scenario and imagery, and generates the resultant imagery (still image or sequence), as it would appear on the operator's display or as an input to an image processing module. The physical models used in IRISIM are based on analytical and empirical models of the imaging process and are implemented in several main modules, including imager characteristics (e.g. optics, scanning, detector, dewar, electronics, display), imager-to-scene geometry, line of sight vibrations and environmental conditions. This paper provides an overview of IRISIM and presents preliminary results of a validation procedure which compares MRTD observer tests using IRISIM simulations to respective lab measurements of actual imagers and to MRTD predictions calculated by TRM3. The results of the validation process indicate a close fit between the compared data sets. Furthermore, IRISIM and TRM3 integration is currently considered as a future platform for IR system performance evaluation.
Panoramic stereo pictures are created by stitching together frames taken from a single moving video camera. Stereo panoramas can be created up to a full 360 degrees. The mosaicing process is robust and fast, and can be performed in real time. Mosaicing starts by computing the motion between the video frames. The video frames, together with the motion between frames computed in the previous step, are used to generate two panoramic pictures: One picture for the left eye and one picture for the right eye. Since the camera is moving, each object is viewed from different directions in different frames. Stitching together strips from the different video frames, selected to have the correct viewing directions for stereo perception, generates the panoramic stereo pictures. The stereo mosaicing process allows several features that were not available before: (1) The creation of stereo panoramic images in 360 degrees. (2) Automatic disparity control: increasing stereo disparity for far away objects, and reducing stereo disparity for close object, to give optimal stereo viewing in all directions and for all distances. (3) The creation of multiple pictures from multiple views, not limited to two views. This enables viewing the panoramic stereo pictures using lenticular technology.
Microlenses can be made by refractive and diffractive optics. A tailored distribution of light creates, in exposed photoresist, a three dimensional pattern, which is then reproduced by ion beam etching in the substrate, resulting in the desired microlens. The first technique uses a Fraunhofer diffraction pattern of a hole in the focal plane of a lens. The second technique uses diffractive optics, i.e. a Dammann grating, to generate a uniform array of equally spaced beams. The theoretical background of a Dammann grating and the experimental results are presented.