Detecting Clear and Reflective Targets

A premier solution for clear and reflective object detection is a laser measurement sensor with dual mode. The small, visible laser spot allows for easier sensor alignment, greater precision, detection of smaller objects, and detection of smaller gaps between objects compared to an LED-based sensor.  In addition, laser sensors with dual mode do not require a reflector for more flexible mounting and reduced inventory and maintenance costs. 

In addition to measuring distance, laser sensors with dual mode also detect changes in light intensity from a stable background condition. In other words, a laser distance sensor with dual mode can detect not only when the target is present within a certain distance but also when it returns a certain amount of light to the receiver.   

For this to work, a stable reference surface must be taught, and the distance and intensity of the reference surface are recorded and used as a baseline. The presence of a transparent or highly reflective object entering the sensing range of the beam alters the perceived distance and light intensity from the background condition. 

Many clear object detection applications occur in food and beverage processing applications, which are often subjected to frequent high pressure, high temperature washdown and/or chemical clean-in-place processes to ensure a safe food chain. 

Sensors rated IP69K are ideal for these environments, as they have been tested to ensure reliable operation even when subjected to frequent cleaning.  A rugged, stainless steel sensor is a popular choice, and in some applications, a sensor made with food-grade materials may be required.  Learn more about IP ratings and what they mean.

In some cases, plastic sensors can also be used, as long as they are properly sealed.  In addition, some photoelectric sensors can see through an aperature, which allows them to be shielded for use in washdown and hygienic environments.