Two Different Types of Sensors
Another application of the thru-beam is used in stores and security alarms. You know the times you walk into a store a sound goes off, well that is because you just crossed through a thru-beam. Same example goes for a security alarm instead of a quick sound this will produce a call sound for help when it is triggered.
Thanks to scientific breakthrough in technology we no longer have to do things like flush public toilets, or open up doors, or even worry about our dog getting crushed under the garage door. So the next time you activate a sensor just remember it could possibly be a photoelectric or a thru-beam sensor.