Heterostructures HgCdTe/CdTe/GaAs grown by molecular beam epitaxy were used for LWIR FPA fabrication. The technology was developed and 32 by 32 and 128 by 128 photodiode arrays with indium bumps of 15 micrometer height in each pixel were fabricated. Mean NEP is 1.7 by 10-13 W/Hz1/2 and 1.1 by 10-14 W/Hz1/2 for 128 by 128 photodiode arrays with (lambda) c value of 10.4 micrometer and 5.2 micrometer correspondently. The technology of hybrid assembling with continuous control of cold welding on the measuring stand was demonstrated on the example of 32 by 32 LWIR FPA. Mean NEP value of 5.4 by 10-14 W/Hz1/2 with (lambda) c equals 10.6 micrometer at 80 K operation were obtained. using an infrared camera system the infrared image was successfully demonstrated. The NETD value of 0.077 K was obtained under 293 K background condition.
A circuit for readout of LWIR photodiode in area FPA is suggested and simulated. It is expected, that the combination of a dynamic current mirror and the buffered direct injection input (DCM-BDI) will be capable of a hundred-fold dark current and background current suppression, and perfect, within a few millivolt over FPA, detector biasing. The estimates are made of which improvement in detectivity the novel readout scheme can bring. To realize fully the benefits of the DCM-BDI readout, the buffer amplifier 1/f-noise should be made as small as 100 nV/Hz1/2 at 1 Hz.
Limitations inherent to the linear optical field assumption are discussed. A modified time-to-crash detector conception is proposed. The main features of our approach are a logarithmic compression of image in space, differentiation of the logarithm of light intensity in space and time, detecting local expansion using a nearest-neighbor logical circuitry, and an automatic choosing of the contour for the time-to-crash estimation.
Keywords: optical flow, smart sensor, CMOS image sensor, motion sensor
KEYWORDS: Sensors, Amplifiers, Transistors, Capacitance, Field effect transistors, Capacitors, Detection and tracking algorithms, Linear filtering, Photodiodes, Digital filtering
Limitations inherent to the linear optical field assumption are discussed. A modified time-to-crash detector conception is proposed. The main features of our approach are a logarithmic compression of image in space, differentiation of the logarithm of light intensity in space and time, detecting local expansion using a nearest-neighbor logical circuitry, and an automatic choosing of the contour for the time-to-crash estimation.
Two CMOS image sensor concepts, developed for motion extraction, are proposed. The algorithm implemented in each pixel is either: the calculation of the temporal variation of the difference of the logarithm of intensity in two adjacent pixels; or a more general implementation of the spatial and temporal filtering over the local neighborhood. Temporal differencing yields peak in the response of pixels with changing intensity. The spatial differencing provides high-pass filtering and invariance to time-varying external lighting. We also compare two ways to use this sensor module to compute the velocity of edges moving along the sensor. In one implementation, the sensor is used as an input for a correlation algorithm, calculating the optical flow vector. The other possibility is to detect motion locally in each pixel, and measuring the time of switching between adjacent pixels which detect the motion.
A number or novel building blocks for constructing early vision neural networks in silicon is presented. It is also shown, that a coding of information with a rate of spikes is a promising strategy in developing both local and global architecture of these networks.
A number of novel building blocks for constructing early vision neural networks (NN) in silicon is presented. It is also shown that the coding of information with a rate of spikes is a promising strategy in developing local and global architecture of these networks.
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