Abstract: A system for detecting displacement of a surface in a direction normal to the surface, the system including a first grating; a second grating; an optical subsystem for projecting an image of the first grating onto the surface and for directing a secondary image of the first grating reflected off the surface onto the second grating; and a detector, responsive to the fringe pattern formed after the secondary image passes through the second grating, for detecting displacement of the surface in a direction normal to the surface.

Abstract: A system for processing particle size and position data for a surface under inspection, the system including an air spindle for rotating and a translation stage for translating the surface with respect to a beam of radiation used to detect particles on the surface; a rotational encoder for dividing the surface into a number N of angular vectors; a counter of counting the number of revolutions of the surface; a processor for collecting particle size and position data at each angular vector during each revolution; first and second FIFO memories having at least N address spaces, each address space allocated for a specific angular vector; and a routine for writing the collected particle size and position data to the first memory and for reading particle size and position data from the second memory and switching memories every M revolutions. The FIFO memories are programmed to store only the greater of stored size data and incoming size data.

Abstract: A surface pit and mound detection and discrimination system including a device for scanning a beam of radiation over a surface, and a mechanism for detecting a local slope on the surface for differentiating between whether the beam of radiation is scanning a pit or a mound on the surface.