1990 Fiscal Year Final Research Report Summary
Nanometric Straightness Measurement of Machine Table Using Laser Beam Straight Datum
| Project/Area Number |
01850032
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Research Field |
機械工作
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| Research Institution | Osaka University |
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Principal Investigator |
IKAWA Naoya Osaka University, Department of Precision Engineering, Professor, 工学部, 教授 (60028983)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Tsutomu Hitachi Zosen Co., Technical Research Institute, Chief Researcher, 電子情報システム研究室, 主管研究員
UCHIKOSHI Junichi Osaka University, Department of Precision Engineering, Research Associate, 工学部, 教務員
SHIMADA Shoichi Osaka University, Department of Precision Engineering, Associate Professor, 工学部, 助教授 (20029317)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Straightness measurement / Straight datum / Error motion / Laser beam / Slide table / エラ-モ-ション |
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| Research Abstract |
A feasibility study is made for the utility and the application of laser beam as a straight datum. By using a quadrant photodiode (QPD) and a piezo-compensator, the specially designed two-dimensional position sensor/compensator for the energy center of the laser beam is developed. The resolution of the position sensor/compensator is estimated to be about 3 nm with the cut-off frequency of about 200 Hz.
Combining the laser beam as straight datum line with QPD position sensor/compensator, the two-dimensional error in straight motion of a certain point on hydrostatic air and oil slide tables are measured within the accuracy of 3 nm. The slide tables have straight error motion more than 50 nm /100mm. However, the repeatability of the error motion have been confirmed to be less than a few nm.
Theoretically, complete analysis of straight motion of a slide table can be executed by measuring the error motion of three different points on the table simultaneously. This call for three parallel laser beams as a set of the datum which are aligned within a required accuracy. The usefulness of the method has been partly confirmed by the experiment using a set of two parallel laser beam.
The most important factor affecting the reliability of the proposed method is the positional and angular stability of the laser beam path. Under the precautions against the thermal stability of the laser tube and the air flow in the beam path, a narrow He-Ne laser beam can be used as the metrological datum line of straightness within the accuracy of 3 nm over the working distance of 200 mm for about 1 minute. To extend the usefulness of the method proposed, the development of highly stable laser beam is essentially required.
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