Intensity response model and measurement error compensation method for chromatic confocal probe considering the incident angle
Mengmeng Xi, Haibo Liu, Donghang Li, Yongqing Wang
Abstract
Chromatic confocal measurement technology is extensively applied in precision surface profiling within the industrial domain. However, due to limited measurement space and the complex shape of surfaces, it becomes challenging to ensure that the optical axis is aligned with the normal direction of the surface, particularly in regions with steep slopes. Although the reflected light can be captured when the probe is tilted within the numerical aperture angle, it introduces measurement uncertainty. In this paper, we investigate the reflective characteristics of incident light and develop a chromatic confocal light intensity response model that accounts for the incident angle. This model is based on the Rayleigh-Sommerfeld diffraction and dispersion theory. Simulation results demonstrate that the tilt angle results in a shift in the peak wavelength of the reflected spectrum. To compensate for the measurement error caused by this wavelength shift, we establish a calibration curve representing the angle and wavelength variation for the chromatic confocal measurement system. Experimental findings reveal that after compensation, the measurement error attributable to the incident angle is reduced by approximately 72 %.