Scientific achievements. Hardware and methodological developments
2024
Development of a Photodetector System Optimized for Photometry Methods Based on a Large-Format CMOS Photodetector
A large-format high-speed photodetector system (PDS) based on a back-illuminated CMOS photodetector GSENSE6060BSI (GPixel, China) with a 6K×6K-element format and a diagonal of 86.8 mm has been developed and manufactured to use at telescopes of SAO RAS and other observatories. The detector is located in a vacuum gaseous head at atmospheric pressure. Due to the antireflective coating of the photodetector, the PDS provides high quantum efficiency of detection of more than 95% at the peak sensitivity at a wavelength of 580 nm. The system ensures high accuracy in maintaining the temperature of the photodetector at a level of ±0.1°C, which allows stabilizing the gain of the video channel (gain instability is 0.064%). The camera cooling system is built on thermoelectric modules and includes air cooling with the possibility of using a liquid heat exchanger. The PDS controller implements the mode of simultaneous image reading in two 12-bit video channels with different gain and their subsequent combination into one frame with an extended 16-bit dynamic range (HDR, High Dynamic Range). The improved combination of frames with high and low gain into an HDR frame ensures the linearity of the “light-signal” transfer characteristic without gain shifts and dispersion at the junction of video channels. The implemented HDR frame mode (necessary for photometry of weak objects) ensures a high dynamic range and nonlinearity of the video channel of 0.69% and has no analogues among photoreceiving systems (of other manufacturers) available for purchase in the Russian Federation. The read images contain geometric noise caused by interference from the operation of the multiplexer control signals and the heterogeneity of numerous readout channels. Real-time frame correction methods allow minimizing geometric noise to values comparable to CCD photodetectors. For the use of PDS in long-exposure photometry methods, modes of dark current reduction, built-in zero subtraction, and video channel gain stabilization are provided. It is also possible to use PDS in fast spectroscopy methods, as part of adaptive optics systems, and fast sky surveys.
Authors:
Afanasieva I.V., Murzin V.A., Ardilanov V.I., Ivaschenko N.G., Pritychenko M.A. (SAO RAS)
Published:
1. Vlasyuk V.V., Afanasieva I.V., Ardilanov V.I., Murzin V.A., Ivaschenko N.G., Pritychenko M.A., Dodonov S.N., Large-format imaging systems based on solid-state detectors in optical astronomy, Uspekhi Fizicheskikh Nauk, 194, 432–445 (2024), doi: 10.3367/UFNr.2023.04.039575
2. Afanasieva I., Murzin V., Ardilanov V., Ivaschenko N., Pritychenko M., Large-format photodetecting system pCam6060 with a GSENSE6060BSI CMOS detector, developed at SAO RAS and optimized for photometric methods, Modern astronomy: from the Early Universe to exoplanets and black holes, Proceedings of the VAK-2024 conference, Aug 25–31, 2024 — Moscow, RIOR, 2024, ISBN 978-5-369-02160-6