Topography inspection by aperture coding confocal sensors

This paper presents a novel family of confocal sensors targeting at topography inspection. In conventional confocal microscopes, displacement is measured by estimating a peak intensity during an optical sectioning. We show that by coding the aperture of the confocal sensor angularly it is possible to simultaneously supplement the distance information with the surface gradient. The angular aperture coding can be performed by exploiting variety of degrees of freedom, among them spectral or polarization encoding. By exploiting an additional tilt information, the proposed sensors are able to lower the lateral resolution requirements, while offering better surface reconstruction abilities. The proposed approach represents a novel family of aperture coding confocal sensors with a wide variety of different targeting applications.