Interferometer, Profiler, Surface
Saturday, September 09, 2006
A Surface Profiler Interferometer was designed and developed to measure the absolute surface figure and middle frequency errors of optical components 1000 mm in length or diameter. The Interferometer consists of an optical head mounted on an air-bearing carriage with a travel range of one meter. It is mounted on a ceramic beam, achieving excellent dimensional stability. A beamsplitter provides two pairs of light beams from a collimated diode laser light source. One light beam is scanned over the sample surface and the other is used as a reference light beam. A closed-loop DC servomotor high-resolution linear encoder system provides carriage positioning along an air-bearing slide.
A stable zero optical path difference is used to generate the test light beam and reference light beam. These light beams are then imaged onto a photodetector array. The interference patterns on the photodetector array are a direct measurement of the local slope of the test surface. Height profile can be derived by integration. The RMS slope error is less than 0.1 arc seconds, with an absolute RMS accuracy in height profile of less than 3 nm over a full one-meter travel range.
Source: Barry Goodman, Continental Optics Corp., Hauppauge, NY;
Reference:
1) U.S. Patent Number 4,884,697
2) Peter Z. Takacs, Brookhaven National Laboratory, Upton, NY and ShiNan Qian
Industrial Products
posted by JD52 @ 6:06 PM,
