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%