G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
G08B13/00—Burglar, theft or intruder alarms
G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
G08B13/181—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
G08B13/183—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
G—PHYSICS
G01—MEASURING; TESTING
G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
G01V8/00—Prospecting or detecting by optical means
G01V8/10—Detecting, e.g. by using light barriers
G01V8/12—Detecting, e.g. by using light barriers using one transmitter and one receiver
G01V8/14—Detecting, e.g. by using light barriers using one transmitter and one receiver using reflectors