Development of a Portable Optical Interferometry Microscope System

摘要

Optical interferometry methods are widely used for measuring microdisplacement with nanometer accuracy. However, most commercially available optical interferometry systems are large and expensive for manufacturing applications. In this study, we report the development of a low-cost portable optical interferometry microscope for factory use. The light source was a tungsten-halogen white lamp with an optical filter. The microscope has an objective lens with a numerical aperture of 0.3, a magnifying power of 10, and field depth of 3.056 urn. Interference images were collected with an NTSC CCD-video camera. The resolution of the interference image is 320 × 240 pixels and stored in BMP format. To obtain phase-shifted interferometry images, a piezoelectric actuator was used to monitor the table movement along the optical axis. The total cost of all system parts is approximately 7000 to 8000 US dollars. To evaluate the basic performance of the developed interferometry microscope, we measured a steel ball, the penetration mark of a Rockwell scale hardness indenter, and a gauge block surface with a bump. The developed interferometry microscope can measure continuous and gently sloping surfaces. The processing time is approximately 10-20 s.