In filling lines, to detect transparent bottles advancing on conveyors, it is necessary to use sensors that are not influenced by color or shape, such Datasensing ultrasonic sensors.
UKR1 Retro-reflective ultrasonic sensors series can be used for similar applications.
The retro-reflection ultrasonic sensors, using a fixed part of the machine as a background, are therefore able to perfectly detect the bottles in transit, whatever their shape are... even the square ones.