How to use Laser Transmitter and Laser sensor for Arduino - YouTube
10pcs 3v-5v 650nm Adjustable Mini Laser Sensor Module 5mw Arduino Red Laser Spot Diode Copper Head Level Meter Ground Wire Meter - Sensors - AliExpress
Amazon.com : Geekstory 5V Laser Receiver Sensor Detection Module Non-Modulator Tube for Arduino Geekstory(Pack of 5) : Electronics
How to build an optical/light barrier with the Arduino, the Keyes laser module (KY-008) and a laser receiver/detector module - Michael Schoeffler