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Entry  Sun May 26 21:47:07 2019, Kruthi, Update, Cameras, CCD Calibration CCD_calibration_setup.png
    Reply  Sat Jun 29 03:11:18 2019, Kruthi, Update, Cameras, CCD Calibration calibration_setup.jpgCCD_calibration_2.jpegGigE_spectral_response_curve.png152_calibration_plot.png
       Reply  Sun Jul 14 00:24:29 2019, Kruthi, Update, Cameras, CCD Calibration CCD_calibration.png
Message ID: 14757     Entry time: Sun Jul 14 00:24:29 2019     In reply to: 14708
Author: Kruthi 
Type: Update 
Category: Cameras 
Subject: CCD Calibration 

On Friday, I took images for different power outputs of LED. I calculated the calibration factor as explained in my previous elog (plots attached).

Vcc (V) Photodiode

Power incident on photodiode (W)

Power incident on GigE (W)
Slope (counts/​𝝁s)
Uncertainity in
 slope (counts/​𝝁s)
CF (W-sec/counts)
16 0.784 2.31E-06 3.89E-07 180.4029 1.02882 2.16E-15
18 0.854 2.51E-06 4.24E-07 207.7314 0.7656 2.04E-15
20 0.92 2.71E-06 4.57E-07 209.8902 1.358 2.18E-15
22 0.969 2.85E-06 4.81E-07 222.3862 1.456 2.16E-15
25 1.026 3.02E-06 5.09E-07 235.2349 1.53118 2.17E-15
  Average  2.14E-15

To estimate the uncertainity, I assumed an error of at most 20mV (due to stray lights or difference in orientation of GigE and photodiode) for the photodiode reading. Using the uncertainity in slope from the linear fit, I expect an uncertainity of maximum 4%. Note: I haven't accounted for the error in the responsivity value of the photodiode.

GigE area 10.36 sq.mm
PDA area 61.364 sq.mm
Responsivity 0.34 A/W
Transimpedance gain (at gain = 20dB) 10^6 V/W +/- 0.1%
Pixel format used Mono 8 bit

Johannes had reported CF as 0.0858E-15 W-sec/counts for 12 bit images, with measured a laser source. This value and the one I got are off by a factor of 25. Difference in the pixel formats and effect of coherence of the light used might be the possible reasons.

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