Unlike regular optical fork sensors, the optical frame sensor has not one but several transmitters and receivers placed opposite of each other. This results in a curtain of infrared light, so that the smallest objects can be detected fast (5 kHz) and with high accuracy. The frame sensors are available with frame opening widths of 40 to 250 mm, the resolution is 0.5 to 4 mm and the sensors have a 3-pin M8 connector. The sensitivity as well as the built-in pulse extender is adjustable with a potentiometer.
Like the fork sensors, frame sensors are optical sensors, where the transmitter and receiver are placed facing each other in a U-shaped aluminum housing or a closed crossbar housing.