The collector is used to receive the electromagnetic radiation energy emitted or reflected by the target, focus them, and then send them to the detection system. The collecting element of the camera is a convex lens; The collecting element of radar is antenna. [1]
Structurally, all types of sensors are basically collector , detector, processor and output device. The detector is a physical element that receives electromagnetic radiation from ground objects. Its function is to realize energy conversion, measure and record the received electromagnetic radiation energy. The commonly used detection elements are photographic film, photoelectric sensor, solid sensor and waveguide.
