LOWFS: detector requirements, speed
Relationship between detector RON, speed, QE and LOWFS loop performance
LOWFS: detector requirements, speedRelationship between detector RON, speed, QE and LOWFS loop performance |
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Show content only (no menu, header)LOWFS for near-IR ground-based systemI assume here that the LOWFS is operating in H band for a near-IR extreme-AO system. There is much value in being able to run down to mH=8, so I assume mH=8, and a 2kHz sampling frequency. On a 8m telescope, a mH=8 target gives 5000 phe/ms integrated in H band assuming a 10% system efficiency. The LOWFS typically must spread this light over a 8 pixel diameter spot = 50 pixel, yielding 100 phe/pix/ms. Assuming a LOWFS efficiency factor of 0.2 (20% of the starlight lands in the LOWFS spot), we have 10 phe/read/pix. At 2kHz sampling, the detector RON must therefore be approximately 5e- or less to operate in photon-noise limited regime.Page content last updated: 27/06/2023 06:35:52 HST html file generated 27/06/2023 06:34:36 HST |