Laser break beam sensors work by detecting an object breaking a laser beam – but you usually have to set up a laser on one end and a sensor on the other. This break beam sensor is slightly different – It has a light sensor + lens next to the laser to detect the reflected dot when the beam is broken, so it can sense when someone breaks the beam from the starting location. There's no need for a matching end point sensor! It forms a good strong laser with a sensing distance of up to 1 meter.

Set up is pretty easy, connect 5VDC to the red wire, Ground to the black wire and a pullup resistor on the output pin. When the beam is broken, the output blue wire will pull down to ground. If it's being pulled up, the voltage will be 'high' when there's nothing in the way of the beam.

• Emitter: 1mW red laser diode
• Operating Voltage: DC 4.5 VDC – 5.5VDC
• Output Current (NPN transistor output): 100mA max
• Response Time: 2ms

• Sensing Distance: Up to 1m
• Operating Current: 25mA
• Sensing Angle: <10 degrees
• Working Environment: Indoor (not waterproof!), 0-70 degrees C