Technology

The transmitter and receiver are packaged in the same housing and mounted opposite a reflector. Light is sent from the transmitter lens, bounces off the reflector and returns to the receiver lens.

As with thru-beam sensors, the output changes state when a target interrupts the beam and starves the receiver of light. As long as the target is large and solid enough to break the effective beam, the color, shape, angle, reflectivity and surface finish will not affect the application. This makes them more reliable than diffuse sensors, which depend on light reflecting off the target.

The transmitter and receiver in a diffuse sensor is located in the same housing. The transmitted light reflects back to the sensor from the target and the receiver evaluates it. It is important to carefully consider the characteristics of the target and the background behind the target when selecting the correct solution for an application. Diffuse sensors have much less excess gain than thru-beam pairs, but typically more than polarized retroreflective types. 

The sensitivity of diffuse sensors is very high. Only 2% of the transmitted light energy reflected off the target will cause the output to switch. 

This technology uses two receiving elements to obtain background suppression. Using a potentiometer for adjustment, a mirror is mechanically positioned to determine the point where one receiver detects the target and the other detects the background. The sensor is then adjusted halfway between these two points. The sensor evaluates the angle of the received light to determine if the light comes from the target or the background.

For more details on photoelectric technology, please click here.