In this work, a time-resolved imager with adjustable single row sampling rate from 1 GS/s to 7.14 GS/s fabricated in standard 0.35 µm SiGe BiCMOS technology is presented. The prototype consists of a vector of 12 photodetectors, a Transimpedance Amplifier (TIA) stage, a 128-deep analog sampling and storage block and a Voltage-Controlled Delay Line (VCDL) for sampling clock generation. The imager demonstrated a 6.7 ns Full Width at Half Maximum (FWHM) 532 nm laser pulse capture with very good accuracy and a 500 MHz 650 nm optical periodical wave acquisition at 7.14 GS/s.
A near-infrared optical tomograph has been developed to obtain 3-dimensional images of scattering phantoms with optical properties similar to those of biological tissues. This experimental setup uses a femtosecond laser and a synchroscan streak camera. Thanks to three stepping motors, the phantom to be imaged is scanned in a parallel-beam mode. The time resolved detection of scattered photons is performed in the transmission mode, for different phantom positions obtained by two translations and one rotation stages. Regarding the data processing, we have developed a nonlinear image reconstruction algorithm based on the Newton-Raphson iterative method. It executes absorption and scattering mapping on the basis of characteristic data extracted from the recorded temporal point spread function of light transmitted through the studied object, such as the mean flight time of photon, the related variance or the integral intensity. First, 2D images using absolute or differential imaging schemes have been obtained for different scattering cylindrical phantoms possessing one or two more absorbing and/or more scattering inclusions. Reconstructed images have been compared to simulated and expected values. The results demonstrate that this system is a reliable and valuable platform for research on time-resolved optical tomography.
Nowadays, imagers based on CMOS active pixel sensors (APS) have performances that are competitive with those based on charge-coupled devices (CCD). CMOS imagers offer advantages in on-chip functionalities, system power reduction, cost and miniaturisation. The FAst MOS Imager (FAMOSI) project consists in reproducing the streak camera functionality with a CMOS imager. In this paper, we present the second version of FAMOSI which makes up for the drawbacks of the first one. FAMOSI 2 has a new architecture of pixel which implements an electronic shutter and analogue accumulation capabilities. With this kind of pixel and the new architecture for controlling the integration, FAMOSI 2 can work in the low power repetitive synchroscan mode. The prototype has been fabricated in the AMS 0.35µm CMOS process. The chip is composed of 64 columns per 64 rows of pixels. The pixels have a size of 20µm per 20µm and a fill factor of 47%.The simulation shows that a conversion gain of 3.4µV/e -is obtained with a dynamic range of 1.2V, a time resolution of 400ps and a light pulse repetitive rate of 300kHz.
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