Image sensors and optical devices

Which evaluation method obtains an image sensor's conversion gain and similar parameters from the relationship between the mean and variance of the signal in images taken at different brightness levels?

  1. AC-V measurement
  2. BThe photon transfer curve (PTC) method
  3. CThe four-terminal method
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Answer: B. The photon transfer curve (PTC) method

For photon shot noise, the variance of the number of signal electrons equals its mean. Plotting the mean and variance of the output from images taken at various brightness levels therefore gives the output per electron (conversion gain) from the slope. The method is also used to evaluate read noise and full-well capacity.

  • A. C-V measurement evaluates MOS structures and the like from capacitance versus voltage.
  • B. Correct. The conversion gain is obtained from the mean-variance relationship.
  • C. The four-terminal method measures resistance precisely.
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