Microscopic Surface Shape Estimation of a Transparent Plate Using a Complex Image

Abstract

This paper proposes a method to estimate the surface shape of a transparent plate using a reflection image on the plate. The reflection image on a transparent plate is a complex image that consists of a reflection on the surface and on the rear surface of the plate. A displacement between the two reflection images holds the range information to the object, which can be extracted from a single complex image. The displacement in the complex image depends not only on the object range but also on the normal vectors of the plate surfaces, plate thickness, relative refraction index, and the plate position. These parameters can be estimated using multiple planar targets with random texture at known distances. Experimental results show that the proposed method can detect microscopic surface shape differences between two different commercially available transparent acrylic plates.