New diffuse laser sensors from Contrinex allow cost-effective sensing of small objects

This type of detection has long posed difficulties for manufacturing engineers and compact, focussed beam sensors or accurately set miniature fibre optics are often used. However, both these methods require that the sensors are situated close to the target and in many applications there is insufficient space to implement these arrangements. As a result, vision systems are sometimes the only practical alternative but such systems are highly expensive and require a high level of application knowledge for reliable deployment.

The Contrinex solution uses a new generation of low cost, precision diffuse lasers in which the beam spot can be reduced to just 0.2mm diameter by use of an adjustable iris. This allows them to detect objects as tiny as 0.1mm diameter at a distance of 150mm making them ideal for detecting small objects or features. The operating distance can be extended by a geared multi-turn potentiometer to 600mm and, even at this distance, targets of 0.6mm diameter can be detected.

The laser beam emitted is 660nm visible red light making alignment and set-up very easy and the sensor has a very high immunity to interference from other bright light sources such as arcs or direct sunlight. To ensure the highest levels of reliability, Contrinex has included a diagnostic feature that continuously tracks the received light. If the light level falls due to dirt accumulation or misalignment the diagnostic ‘excess light’ function output is triggered alerting the user to check the set-up before the principle output fails thus reducing expensive production line stoppages.

These new M18 Contrinex laser sensors have an operating frequency of 5,000Hz and this short response time ensures that even the smallest components do not escape detection. Sealed to IP67 they are supplied in a body length of only 50mm and are made from tough stainless steel.

The sensors have a wide operating supply voltage from 10 to 30 VDC, a switched current rating of 200mA and a stable sensing range from -25°C to +55°C and are short-circuit and inverse polarity proof and overload protected.