1999 Fiscal Year Final Research Report Summary
Three-dimensional optical profilometry with detection of weakly diffused light
| Project/Area Number |
10650267
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Intelligent mechanics/Mechanical systems
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| Research Institution | RIKEN (The Institute of Physical and Chemical Research) |
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Principal Investigator |
KATO Jun-ichi Optical Engineering Laboratory, Senior research staff, 光工学研究室, 先任研究員 (70177450)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Wavelength-scanning interferometry / Phase-shifting technique / Laser diode / Profilometry / Wide dynamic range imaging / Quasi specular surface / Weak defused light |
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| Research Abstract |
To realize a accurate three-dimensional optical profilometry for quasi-specular or rough surfaces constituted of discontinuous steps or isolated parts, such as metallic molds and micro-machined parts, we developed a novel wavelength-scanning interferometry, which is based on a phase-detection and has wide dynamic-range in imaging against the weakly diffused light. By using a external-cavity laser diode with the wavelength tuning range of 8nm by 0.2 nm step, and phase-shifting technique using a PZT mirror in Michelson interferometer, a height resolution of 40 nm was experimentally attained by detecting a phase-slope against the wavelength change at each pixel. To obtain adequate contrast conditions between weakly diffused light and specularly reflected one simultaneously, we adopted a polarization selection technique. A small change in polarization state of the diffused light was selected with a polarizer whose azimuth was set to almost perpendicular to the linearly polarizing direction to be interfered with a small fraction of linearly polarizing component comes from the specular surface. This technique accomplished a precision step height measurement and was applied to a gauging of height distribution of isolated objects such as a metallic bump array placed on a silicon wafer surface.
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Research Products
(2 results)
