White Light Chromatic Confocal Sensor Technology
White light chromatism is the phenomenon of white light wavefront splitting into its spectral components‘ wavefronts as light travels through an optical lens system. Different wavelengths move at different speeds. Shorter wavelengths move slower than longer wavelengths. In the axial direction, the chromatism causes chromatic defocus, as shown in the figure below. Though the spectral components of white light emit from the same spot, they are focused on different axial altitude. A axial chromatism sensor combines the axial chromatism and confocal technologies together. The confocal technique ensures that only focused light passes through the spatial filter, and the axial chromatism assures that only a single wavelength is in focus on certain altitude. Thus by detecting the wavelength passing through the spatial filter using a spectrometer, the sensor can measure the distance between the sample and the sensor.