detector; locator
A device that detects or locates something, such as metal, gas, or submarines. Often used in compound nouns like 金属探知機 (metal detector).
I passed through a metal detector at the airport.
This detector quickly finds gas leaks.
探知 is the act of detecting or locating, while 探知機 is the device that performs that action.
センサー is a more general term for a sensor, often used in engineering contexts, while 探知機 implies a complete detection device.
Standard kanji spelling; the most common form in news and technical contexts.
Alternate kanji spelling using 器 (instrument/device); less common but still seen in some product names or older texts.
Compound of 探知 (detection) + 機 (machine/device). The kanji 探 means 'search', 知 means 'know', and 機 means 'mechanism'.