Imaging Seekers 

• Although there are a wide variety of imaging sensors (cameras), the majority of modern aircraft systems are based on conventional TV camera technologies (albeit in a slightly modified form for infrared cameras). 
• A TV or video camera is usually a Charged-Coupled Device (CCD) and has four main components: 

- Optics: aperture, lenses, optical filters.
- Photodetector array: e.g. photodiodes.
- Read-out circuits: integration circuit, automatic gain-offset correction, and analogue-to-digital (A2D) converters.
- Storage: electronic memory, tape or disk.

• The photodetector array is often referred to as a focal plane array, because this is where the image is formed by the optics. 

- Although, this array can sometimes be a linear array and the image is scanned rather than collected directly as a single image.

• A modern imaging seeker system is likely to be based on exactly the same technologies.