DISPLACEMENT DETECTION OF SMALL SPHERE USING ECCENTRIC ASTIGMATIC METHOD |
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| Hiroki Shimizu, Atsuo Ogawa, Yoshinori Sasaki, Yuuma Tamaru |
- Abstract:
- To develop a micro tactile probe used with a micro coordinate measuring machine (CMM), a novel technique for detecting a three dimensional displacement of a small sphere with high sensitivity has been proposed. In this technique, a surface of a metal sphere is included as a spherical mirror in an optical system and changes of optical path arise from displacement of the sphere is detected with a sort of the astigmatic method. In the optical system, three eccentric collimated beams are generated and each beam moves parallel to the optical axis. The beam is converted to spherical wave by an objective lens and moving toward the focal point. At this time, if a spherical mirror (metal sphere) is placed in the position of which center falling on the focus, incident angles of all rays become right angle and reflected rays go back on the incident paths. On the other hand, if the spherical mirror moves from the point in the small distance, return path of each reflected ray is changed large. This change can be detected with the astigmatic method using a condenser lens and a CCD. The relationship between displacement along three axes and the change of the spot radius made by astigmatic method was calculated using a ray tracing code. As a result, the change of the spot shape was simulated only with the motion along one axis. This result shows the feasibility of three dimensional displacement detection by the proposed method.
- Keywords:
- astigmatic method, micro-probe, tactile probe, coordinate measuring machine
- Download:
- IMEKO-TC14-2014-47.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC14
- Event name:
- TC14 LMPMI Symposium 2014
- Title:
11th Symposium on Laser Metrology for Precision Measurement and Inspection in Industry
- Place:
- Tsukuba, JAPAN
- Time:
- 03 September 2014 - 05 September 2014