Computer Rigid Disk Surface Assessment With Laser Interferometry Using DDS

Abstract

Laser interferometry in conjunction with the data dependent systems (DDS) methodology is first used in this paper to eliminate errors caused by instrumentation and software, and to recover the surface topography of a computer rigid disk used for illustration. The DDS methodology is then applied once more to decompose the surface height profile into a series of exponential and sinusoidal modes. The significant modes are related to the waviness and surface roughness resulting from different manufacturing processes. Surface reconstruction using only the important modes is presented. This provides a visual as well as mathematical description of the resultant effect of each process. The methodology can characterize very complex surface textures, reducing the reliance on complicated and expensive instruments needed for inspection, and replacing them with relatively inexpensive but reliable computation.