Laser triangulation sensor uses blue laser technology
26 September 2011
Micro-Epsilon has launched what it is claiming is a world first in laser triangulation sensor technology. The innovative Blue Laser Sensor offers significant benefits for users who need to measure the position or displacement of red-hot glowing metals as well as translucent targets. The optoNCDT 1700BL sensor series is suitable for measurements on hot, glowing metals, particularly in hot steel processing applications, as well as for measuring organic materials such as skin, foodstuffs, plastics,
With red, glowing objects, a conventional red laser has a high signal interference from the object surface, because it emits the same or very near wavelengths of light as the red laser. However, the blue laser works at a wavelength of 405nm, which is far from the red part of the visible spectrum. This means it is easier to filter this type of emitted light from the object, which ensures very stable signals. The blue laser therefore measures extremely well on both glowing metals and ceramics. This is a unique advantage, for example, when it comes to measuring the wear or deformation of automotive brake discs under load.
In addition, there are significant benefits to be seen when measuring against translucent objects such as organic materials, paper, some plastics and wood veneers. Unlike a red laser, the blue laser light does not penetrate into the measuring object because it has a lower intensity laser spot and therefore offers more stable, precise measurements on targets that conventional red laser sensors have difficulty measuring.
Micro-Epsilon’s Blue Laser Sensors are equipped with new high-end optical lenses, a new intelligent laser control and evaluation algorithms. The sensors are suitable for red glowing metals up to 1,600 deg C, and for silicon up to 1,150 deg C.
The optoNCDT 1700BL operates using the laser triangulation principle. A laser diode projects a visible point of light onto the surface of the target object. The light reflected from this point is then projected onto a CCD array. If the target changes position with respect to the sensor, the movement of the reflected light is projected on the CCD array and analysed to output the exact position of the target. The measurements are processed digitally in the integral controller. The data is output via analogue (I/U) and digital interface RS422 or USB.
Most suppliers can only offer sensors with a fixed measurement rate, which is selected by the manufacturer as a ‘best case fits all’. This means that for most surfaces, the user then has to rely on averaging the output data to reduce the noise level or error on the output, which gives lower accuracy. However, using Micro-Epsilon’s software algorithms, the measurement rate on the sensor can be slowed down for difficult surfaces. This means it can compensate in real time, and the exposure time of the laser light on the CCD can be optimised for the surface of the object to be measured, resulting in higher accuracy measurements.
The optoNCDT 1700BL series includes six sensor models with measuring ranges from 20mm up to 1,000mm. The measuring rate of the sensor can be adjusted up to 2.5 kHz and can be used as a freely programmable limit switch. Maximum linearity is 16m. Maximum resolution is 1.5m at 2.5 kHz (without any averaging). High flexibility cables can be provided for use with robots. A calibration certificate is included as standard.
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