Confocal sensors

Bestech has released the optoNCDT 2403 confocal chromatic sensor. With an external diameter of 8 mm, the device is similar to the optoNCDT 2402 range of miniature sensors.

Due to a larger digital aperture, this latest sensor can receive more reflected light.

Polychromatic white light is focused onto the target surface by a multi-lens optical system that disperses it into a series of monochromatic light. A specific distance to the target is assigned to each wavelength by a factory calibration.

The light reflected from the target surface is then read by a spectrometer which detects and processes the spectral changes.

This allows displacement measurement in a limited space, with sub-micron accuracy and extreme spatial resolution. The confocal displacement measurement system also allows the one-sided thickness measurement of transparent materials.

An ancillary lens is positioned before the optical system and, due to its greater divergence, the so-called relay lens enables more reflected light from the target to be detected.

This is particularly beneficial if the sensor has to be tilted or if the target is non-planar, so that the reflected light is only reflected back by an angular deviation in the sensor.