Non-contact laser line triangulation displacement sensors

Two optoNCDT 1700LL laser line displacement sensors from Micro-Epsilon are mounted to a purpose-built handling and processing machine manufactured by Behr Systems GmbH. The sensors are mounted at two different measuring points on the machine, from which they are able to accurately measure the distance to the surface of the synchroniser discs. The sensors are mechanically shielded and so measurement data is unaffected by the close proximity high-temperature (500W) deburring laser. The sensors for this particular application have a measuring range of 20mm and operate at a wavelength of 900nm to 1070nm. Ambient operating temperature is from 10degC to +50degC. Linearity is less than 50um.

The optoNCDT 1700LL is a non-contact laser line triangulation displacement sensor that is ideal for the high-speed measurement of shiny metallic and rapidly changing, rough or other difficult-to-measure surfaces. Rather than using a spherical or point-shaped laser spot, the sensor uses a laser line and special software algorithms to filter out any interference caused by very small (sub-micrometre) surface defects on shiny objects such as polished metals and mild steel. The sensor uses a special cylindrical lens that widens the laser spot to an oval shape. Although this shape appears as oval to the human eye, the actual shape is a very small line. Measurements using this laser line are then averaged using Micro-Epsilon's patented software algorithms, so that any interference caused by surface roughness, defects, indentations or holes down in the sub-micrometre range are reduced.

Micro-Epsilon's optoNCDT 1700LL is suitable for measuring on structured surfaces, where the distance to the surface and not the structure itself needs to be measured. The distance measurement should not be influenced by the structure of the surface, but instead should provide a constant, reliable value of the distance from the target.

Real-time surface compensation

The optoNCDT 1700LL uses Micro-Epsilon's RTSC (Real-Time Surface Compensation) technology, which enables the sensor to automatically compensate in real time for difficult-to-measure surfaces. When combined with high-speed software algorithms, RTSC reduces signal noise at high measurement speeds. When users need to measure against a shiny surface, they require a sensor that is able to automatically adjust the laser pulse duration (or laser on time) of the sensor to give them the optimum exposure time on the CCD for that particular surface. This, in turn, provides a higher accuracy measurement due to lower noise level on the output signal.

Also available is a range of interfaces including RS422 and analogue output. The sensor also provides various options for signal processing and data output, including peak selection (peak-to-peak), masking of the video signal, data reduction, averaging, exposure time, error status, time stamp, filtering and statistics (min and max).

Four models of the optoNCDT 1700LL are available, with measuring ranges from 2mm up to 50mm. Resolution is down to 0.1um and linearity is down to +/- 0.1um. Data output is via Ethernet, RS422 or EtherCAT. The sensor is also compact, measuring just 80mm by 75mm by 30mm.

For more information about optoNCDT 1700LL non-contact laser line displacement sensors, please email [email protected] or visit the website at www.micro-epsilon.co.uk.