Omron Corporation manufactures the E3S-BD61 photoelectric switch. The reflective sensor is a compact unit, which houses both the light source and the receiver.
Light reflects off an object's surface back to the receiver.
Photoelectric Sensor An advantage of this type of sensor is that it is inexpensive and easy to install. The sensor allows the hand to gain knowledge of the environment without having to actually touch or grasp an object. A disadvantage is its limited sensing distance and resolution which depends on the object's surface condition. Two photoelectric sensors are installed in the center of the palm, parallel to each other. This action helps predict the timing needed to close the hand.