Micron Resolution Optical Scanner for Silicon Detectors

The emergence of high position resolution (~10 microns) silicon detectors in recent times have highlighted the urgent need for the development of automated optical scanners of micron level resolution. They also have to be integrated with associated data acquisition system to be used for characterizing transient response of such photosensitive detectors. Our group has been working on in-house development of such facility to characterize new generation of solid state photo-devices called, Silicon Photo Multiplers (SiPMs). We have designed and fabricated high-resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse profile of the beam was measured using the knife-edge method to be 1.7 microns at 1 sigma level. The scanner is integrated with online CCD imaging system and DAQ system for SiPM characterization. Different regions of SiPM were characterized by mounting the device on a target plane, which can be moved in all directions with a accuracy of 0.1 microns. The design and operational details of the optical scanner with high precision programmed movement of target plane (0.1 microns) integrated with general-purpose data acquisition system will be presented. Active and dead regions on SiPM could be clearly identified using this scanner. Results from detailed characterization of SiPM carried out using this scanner will be presented. Our group is also working on a programmable multi-channel power supply with built-in temperature dependent gain compensation. Progress on this work will be highlighted.