Photometric Stereo Processing for Microscopy

This paper proposed a method of 3D reconstruction of scanning electron microscope (SEM) specimen. The aim is to explore the possibilities of topography reconstruction of microscopic samples, as well as to attempt to solve the task using tools already available on conventional scanning electron microscopes. The proposed solution uses images from a four-segment backscattered electrons detector as an input to the photometric stereo algorithm. This algorithm exploits the fact that the brightness of the image point is dependent on the inclination of the sample surface. Reflectance maps are used to estimate the inclination in each pixel, creating a map of normal vectors. The map is then used for topography reconstruction. A novel technique for reflectance map estimation is proposed. This method is applied to tin samples to remove the sample's atomic number effects. The fact that all data are acquired simultaneously allows for fast reconstruction. Usage of already available and widespread tools eliminates a need for specialized equipment such as Atomic Force Microscopes.

Photometric stereo, Scanning electron microscopes, 4-segment BSE detector, 3D reconstruction