Chromatic Probe For Surface Microtopography Inspection And Analysis

An optical device is described that performs height data acquisition by focusing a white light beam at a sample surface and processing the backscattered light. The principle of the operation is based on longitudinal chromatic aberration of the focusing lens and spectral analysis of the image irradiance. The surface microtopography is reconstructed after automatic point by point scanning. A personal computer interfaced to the probe controls the operation and produces the roughness parameters. Inspecting optical surfaces, the height data are considered as optical path differences and processed according to standard methods of optical testing, eventually working out the absolute shape parameters. The main system characteristics are discussed, and performance examples on selected objects are demonstrated.