Manta G032 camera measurements

Overview

This page contains data from the demo I did in lecture on 9/22/2015 of the Manta G032 camera.

The point was to measure the gain $ g $, dark current $ I_d $, and read noise $ N_r $ of the Manta G032 cameras we use in lab.

Measurement procedure

• Light source directed at the camera so to produce a range of intensities
• 100 frame movie recorded at 20 FPS with an exposure of 150 μs.
• 100 frame dark movie recorded with identical settings.
• Variance of each pixel (noise squared) plotted versus average value (signal).

Calculations

The expression for the value read from pixel $ x,y $ during time interval $ t $ is:

$ P_{x,y}[t]=g \left(I_{x,y}[t]+R_{x,y}[t]+D_{x,y}(t)) \right) $,

where

• $ I_{x,y}[t] $ is the number of photoelectrons that are generated during interval $ t $,
• $ R_{x,y}[t] $ is the read noise during time interval $ t $,
• and $ D_{x,y}[t]<math> is the number of dark current electrons generated during time interval <math>t $

The variance $ P_{x,y} $ is equal to the noise squared. $ P_{x,y} $ is the sum of three terms. The total variance is equal to the sum of the variances of individual term. $ I_{x,y} $ is Poisson distributed, so its variance is equal to its mean, $ \langle I_{x,y} \rangle $. The second term has a constant variance that is a property of the camera, $ N_r $. The third term is Poisson distributed, with an average value of $ I_d \delta t $. This gives:

$ \left\langle\left(P_{x,y}-\overline{P_{x,y}}=g\left(\langle I_{x,y}+N_r^2\right)\right)\right\rangle $