1. 探测器;检测仪
A detector is an instrument which is used to discover that something is present somewhere, or to measure how much of something there is.

1. any device that receives a signal or stimulus (as heat or pressure or light or motion etc.) and responds to it in a distinctive manner

Synonym: sensorsensing element

2. electronic equipment that detects the presence of radio signals or radioactivity

3. rectifier that extracts modulation from a radio carrier wave

Synonym: demodulator