In-situ measurement of surface roughness using chromatic confocal sensor

Abstract

Surface roughness is an important characteristic which affects the quality, performance and lifetime of many types of industrial products, ranging from mechanical and biomedical parts to semiconductors and optics. In recent years, in-situ measurement for surface roughness is increasingly demanded to provide real-time feedback and reduce systematic errors of realignment and repositioning during manufacturing. Commercially available instruments, such as stylus profilometer, confocal laser scanning microscope and coherence scanning interferometer, are limited to a relatively low measurement speed and difficult for in-situ measurement. In this paper, an in-house developed surface measuring system using chromatic confocal sensor was integrated into a mass finishing cell to perform in-situ and non-contact surface roughness measurement. The surface roughness parameters are calculated and evaluated according to ISO 4287 and ISO 4288. From the preliminary experiments, it was verified that the relative error of surface roughness measurements can be kept within 5%.