Applications involving roll diameter measurements, part contouring, and thickness measures often require sensors with the ability to sense these measurements from a distance.  Newer versions of photoelectric sensors can accommodate this requirement.

Photoelectric sensors today come in a greater variety than ever.  Advances in emitters, receivers, lenses, and processing circuits have led to products with longer ranges, better resolution and higher switching frequencies.  The two most common photoelectric sensor measurement technologies — Triangulation and Time-of-Flight — let you implement solutions that are both robust and affordable.

Distance sensors using Triangulation technology use the laws of geometry to assess how far a target is from the sensor.  The emitter sends light towards the target through its outgoing lens.  The target reflects light back to the receiver, and as its position changes, so does the angle at which the light comes back through the receiving lens.  This returned light is then converted to highly accurate position information.

Photoelectric sensors with Time-of-Flight features are recent introductions to the market. They work similarly to the principle of RADAR, emiting a light waveform with specific characteristics that can be marked.

A newer technology available in the market is called Time-of-Flight sensing.  Working similarly to the principle of RADAR, these laser sensors emit a light waveform with specific characteristics that can be marked.  The light travels from the sensor, reflects off of the target, and returns.  The amount of time it takes for the light to make this trip is recorded from the marked waveform, and thus the position of the target is recorded.

Distance sensors often use Triangulation technology, which use the laws of geometry to assess how far a target is from the sensor. 
 
Typical features for long range sensors include one analog output, a discrete output and a sensitivity adjustment for the discrete output.  With sensing ranges of up to 10 m, these features help maximize productivity in complex control schemes. 

Common applications for these technologies include roll diameter measurement, positioning of assemblies, bin level measurement, part contouring and thickness detection.  In all, today’s industrial measurement photoelectric sensor has branched out into many new markets where customers have the need extend their sensing range.

By Roger Altendorf at [email protected]
www.balluff.com/bod