What Is a Transparent Object Detection Sensor?

OPTEX FA's transparent object detection sensors are used in a wide range of industries, including film, plastics, glass, food and beverage, automotive, and semiconductor manufacturing. They are highly valued for their outstanding detection stability and accuracy.
Furthermore, these sensors can reliably detect a broad range of transparent objects, making OPTEX FA's transparent sensor lineup one of the industry's most comprehensive and advanced.

This is a type of retro-reflective photoelectric sensor.
Conventional retro-reflective sensors cannot detect transparent objects because most of the light passes through them.
To address this issue, transparent object detection sensors are designed with a smaller hysteresis, enabling reliable detection of transparent objects.
A smaller hysteresis alone, however, can make the sensor more susceptible to chattering (repeated ON/OFF switching) and false operation caused by noise. Therefore, both the optical system and circuit design have been specifically optimized for transparent object detection.

In a through-beam sensor, light makes a single pass through a transparent object. In contrast, in a retro-reflective sensor, the light makes a double pass through the object, making the received light more susceptible to attenuation.
For example, if the received light amount is reduced by 3% when passing through a transparent object, a through-beam sensor experiences only a 3% reduction. However, a retro-reflective sensor experiences a 6% reduction because the light makes a double pass through the object. As a result, a retro-reflective sensor can detect transparent objects approximately twice as easily.