Image sensors and optical devices

What is the definition of the quantum efficiency of an image sensor?

  1. AThe number of outputs relative to the number of pixels
  2. BThe ratio of electrons generated and collected as signal to the number of incident photons
  3. CThe ratio of output voltage to supply voltage
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Answer: B. The ratio of electrons generated and collected as signal to the number of incident photons

Quantum efficiency is the fraction of photons entering the sensor that are converted into electrons and collected as signal. It varies with wavelength, and a higher quantum efficiency means a more sensitive sensor. Backside illumination and microlenses are techniques for raising it.

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