Two-dimensional surface profile imaging technique based on a double-grating frequency shifter.
A two-dimensional surface profile imaging technique that uses a low-coherence heterodyne interferometer is proposed. A double-grating frequency shifter was used in a tandem interferometer to provide the achromatic frequency shift for low-coherence light. A chopper, together with a processing circuit, was implemented to modulate the interference fringes. The surface profile was measured from the interference fringes taken by a CCD camera using a five-step method. The uncertainty in the displacement measurement is 0.34 microm for a displacement range of 43 microm. The surface profile of a glass sample with low effective reflectivity was acquired.
Wang
Kaiwei
K
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China. wkw01@mails.tsinghua.edu.cn
Zeng
Lijiang
L
D000465:Algorithms; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D007368:Interferometry / Q000379:methods*; D012031:Refractometry / Q000379:methods*