AQA A-Level Physics/Charge Coupled Devices (CCD)

Charge Coupled Device - A CCD is a silicon chip divided into picture elements (pixels) - Incident photons cause electrons to be released - The number of electrons liberated is proportional to the intensity of light - These electrons are trapped in 'potential well' in the CCD - An electron pattern is built up which is identical to the image formed on the CCD - When exposure is complete, the charge is processed to give an image - Quantum efficiency of a pixel is greater than 70%