One unit emits an infrared beam invisible to the naked eye.
Garage door photo eye beam width.
It consists of two units installed about 4 inches from the floor on each side of the door.
The second is photoelectric.
Proper height for a garage door sensor is 4 to 6 inches 10 2 to 15 2 cm.
Higher than that can miss many low lying objects including pets.
They shoot an invisible beam between them which will sense if something is between them as it breaks the beam.
The photo eye of an automatic opening garage door is a safety feature.
If something breaks the beam while the door is closing the opener motor automatically reverses direction and opens the door.
The other unit is a reflector.
These sensors sit either side of your garage door near the ground.
If your garage door sensors are outside of this range remove them entirely from the garage door frame and install leveled inside the safe zone.
The photo eye sensor is one of the most important parts of your garage door system.