This is a diffused reflection laser sensor that has an integrated IR transmitter and a receiver. This sensor using light that transmit by the Laser and receive by the Infrared since the laser adopts modulation processing technology, the receiving tube
Wiring The Laser Transmitter on Photocell with Microcontroller
Another illustration how to build a simple physical intrusion detection with laser and photoresistor (or light-dependent resistor, LDR, or photocell). This guide shows how to wire and build a laser tripwire that triggers an alarm or output when the laser