by interruption of a radiation beam or barrier

Full Title

Burglar, theft or intruder alarms > Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength > using active radiation detection systems > by interruption of a radiation beam or barrier

Child Classifications

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• G08B 13/184 using radiation reflectors
• G08B 13/186 using light guides, e.g. optical fibres