Light Displacement
Measurement of distance or surface topography is achieved by exploiting the longitudinal chromatic aberration of a lens system to map wavelength to focal height. A chromatic confocal sensor uses this principle to detect the exact point where a specific colour of light focuses on the substrate. No moving parts are required for the z-axis scan.
This device captures the height of a coating or the roughness of a board surface with sub-micron precision.
Optical Mechanism
White light passes through a series of lenses that deliberately separate the spectrum into a range of focal points at different distances from the probe head. Only the wavelength that focuses exactly on the material reflects back through a small pinhole to the spectrometer. This selective filtering allows the chromatic confocal sensor to ignore ambient light and out of focus reflections.
It works effectively on both matte and glossy surfaces common in high end packaging.
Production Utility
Quality control systems use these probes to monitor the thickness of wet films or the depth of embossed textures in real time. Because the measurement is non-mechanical, it does not mark the delicate surface of the paper. This speed enables the inspection of every sheet on a moving web.
Chromatic confocal sensor technology provides the data needed to adjust ink keys or lacquer application rates instantly.
