Udi Mizrahi

Advanced features of SCD’s uncooled detectors

SCD has recently presented an uncooled detector product line based on the high-end VOx bolometer technology. The first FPA launched, BIRD, is a 384×288 (or 320×240) configurable format with 25 μm pitch. Typical NETD values for these FPAs range at 50 mK with an F/1 aperture and 60 Hz frame rate. These detectors also exhibit a relatively fast thermal time constant of approximately 10 ms.In this paper we elaborate on the special advanced features that were incorporated within the ROIC and supporting algorithms. In this framework we have addressed two important issues: the power consumption and the time span between shutter activations. Minimum power consumption is a critical issue for many un-cooled applications. SCD has addressed this by introducing the “power-save” concept accompanied with flexible dilution architecture. The paper will present recent results exhibiting the various advantages.One of the limiting factors on the performance of uncooled detectors is their vulnerability to ambient drift. Usually, even minor temperature fluctuations are manifested as high residual non-uniformity (RNU) or fixed pattern noise (FPN). As a result frequent shutter operations must be applied, with the risk of blocking the scenery in critical time frames. The challenge is thus twofold: to increase the time span between shutter corrections and achieve better control of its activation.For this purpose BIRD provides two complementing mechanisms: A real-time (frame-by-frame) ambient drift compensation accompanied by an RNU prediction mechanism. The paper will discuss these features in detail and present illustrative system implementations.

Spatial resolution of SCD's InSb 2D detector arrays

The two-dimensional spatial response of a pixel in SCDs 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.

New developments in SCD's 17-μm VOx μ-bolometer product line

Last year we have introduced the development program of SCDs 17μm pitch VGA VOx μ-Bolometer detector (1). Due to the overall size, weight and power advantages the 17μm pitch is currently being considered for the next generation systems such as thermal weapon sights (TWS), driver vision enhancers (DVE) and digitally fused goggles (DENVG). In the first part of this paper we will discuss in detail the performance of this detector. Specifically, we will elaborate on the radiometric results, ROIC performance and operability. Detailed measurements for a wide temperature range will be presented as well. In the second part, we will describe some new capabilities and features that are enabled by the advanced 0.18um VLSI technology. These features will be embedded in new products that are currently under development.

Large-format 17μm high-end VOx μ-bolometer infrared detector

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.

SCD's uncooled detectors and video engines for a wide-range of 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.

The architecture and performance of SCD's 17 μm pitch VO x μ-bolometer detector

In this paper SCDs 17μm pitch large format VOx μ-Bolometer detector is introduced. In the first part the radiometric performance and the challenges involved in achieving the desired pixel sensitivity are discussed. We elaborate on the progress towards the performance design goal (< 50mK@F/1, 60Hz) utilizing various test structures and technology demonstration platforms. The combination of reduced pixel size and high-end thermal sensitivity can provide smaller light weight systems. In the second part the ROIC architecture options will be presented in depth. New capabilities and features are enabled by the advanced 0.18um VLSI technology. Explicitly, we address the contribution in terms of system flexibility, simplification and reduced power dissipation. Some vital tasks, such as coarse non-uniformity correction, are done internally thus facilitating the user interface.

Advanced μ-bolometer detectors for high-end applications

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.

Cooled and uncooled infrared detectors for missile seekers

Electro-optical missile seekers pose exceptional requirements for infrared (IR) detectors. These requirements include: very short mission readiness (time-to-image), one-time and relatively short mission duration, extreme ambient conditions, high sensitivity, fast frame rate, and in some cases small size and cost. SCD is engaged in the development and production of IR detectors for missile seeker applications for many years. 0D, 1D and 2D InSb focal plane arrays (FPAs) are packaged in specially designed fast cool-down Dewars and integrated with Joule-Thomson (JT) coolers. These cooled MWIR detectors were integrated in numerous seekers of various missile types, for short and long range applications, and are combat proven. New technologies for the MWIR, such as epi-InSb and XBn-InAsSb, enable faster cool-down time and higher sensitivity for the next generation seekers. The uncooled micro-bolometer technology for IR detectors has advanced significantly over the last decade, and high resolution - high sensitivity FPAs are now available for different applications. Their much smaller size and cost with regard to the cooled detectors makes these uncooled LWIR detectors natural candidates for short and mid-range missile seekers. In this work we will present SCDs cooled and uncooled solutions for advanced electro-optical missile seekers.