Interferometric Surface Texture Measurement in the Presence of Error Sources
 
 

Erik J. Salisbury | PhD | 1995

ABSTRACT:

The development of new precision manufacturing processes, has produced products with surface roughness values that are measured in nanometers. The precision surface texture has created the need for measurement techniques that can accurately measure surface texture on the nanometer level.One technoque that has been studied and used for small distance measurements since the 1950's is interferometry. However, a number of environmental error sources degrade the accuracy of interferometric devices and therefore limit their use in manufacturing environment. Techniques that eliminate the effects of "noise" on the measurement are needed to allow manufacturers to measure surface texture on the shop floor.

The focus of this work is the development of interferometric techniques that eliminate or reduce the effects that environmental error sources have on the accracy of the surface measurement. The techniques are software related and therefore require no additional or specialized hardware. Initially, a single fringe reconstruction technique is developed and verified both through simulation and experiment. Next a non-linear least square technique is used to estimate surface height using phase shift interferometry. A general phase shift interferometry algorithm that uses the estimated phase shifts and requires less computation than the full non-linear least squares technique is then developed. Finally, the interferometry system is verified through a number of experiments.

If you have any comments or suggestions please e-mail jwsuther@mtu.edu.