A Coaxial Interference Laser Profiling System With Sub-nanometer Resolution

In pace with the development of high-technology, the applications of ultraprecision machine are becoming more and more. That requires advanced testing instruments, therefore the nanometer testing technologies are increasingly important. In recent ten years, some researchers in the world have made a lot of studies on the measuring methods of ultraprecision machining surface, and have produced some new principles of measurement.The author has analyzed some typical prevailing nanometer testing methods, and developed a new coaxial interference laser profiling system with sub-nanometer resolution, which can be used to test micro-profile.In this paper a new profiling system is presented, which has a light source of a stabilized He-Ne laser with two longitudinal modes. It has agood characteristic on dynamic test as soon as static. The most important is that the profilometer has two coaxial interference arms, the measuring arm is focused on the sample surface to form a spot while the reference arm forms a large spot. Therefore the mechanical vibration and air turbulence has very small effect on the instrument performance. And it doesn't require costly guide or special measuring circumstance. Besides,the system has a high resolution and is convenient for operation.This measuring system has efficient data processing, sub-nanometer resolution, high precision and repeatability. It still has better lateral resolution compare with other profiling systems, and consists of ordinary optical components, mechanical parts. Besides it has superior form accuracy and vibration resistance, which makes it capable of measuring the surfaces with microstructure under conventional condition. It is not very sensitive to curved surfaces of sample, so that it can be used for industry measurement, and the modified type of this profilometer has been used as an on-machine measuring instrument in ultraprecion machining.