A correction on the previous elog about the REFL33Q noise:
Rana pointed out that the whitening filter's input referred noise should not be such high (I have estimated it to be at 54 nV/sqrtHz).
In fact the measurement was done in a condition where no laser is on the photo diode by closing the mechanical shutter at the PSL table.
Therefore the noise I called "whitening filter input referred noise" includes the voltage noise from the RFPD and it could have such a noise level.
So the noise curve drawn in the plot should be called "whitening filter + RFPD electronics noise".
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A feasibility study of the REFL33Q as a MICH sensor was coarsely performed from the point view of the noise performance.
- Whitening filter input referred noise
- I assumed that it is flat with a level of 54 nV/sqrtHz based on a rough measurement by looking at the spectrum of the LSC input signals.
- The contribution was estimated by applying some gain corrections from the conversion efficiency of the demod board, transimpedance gain, responsivity and the optical gain.
- This noise is currently the limiting factor over a frequency range from DC to 1 kHz.
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