Self-calibration of a variable-line-spacing grating for an absolute optical encoder with a Fizeau interferometer
Description
<jats:title>Abstract</jats:title> <jats:p>The principle of the self-calibration method for the evaluation of a planar scale grating having a constant pitch is extended to realize the evaluation of the pitch distribution of a planar scale grating having variable line spacings (VLSs) along the <jats:italic>X</jats:italic>- and <jats:italic>Y</jats:italic>-directions. In the conventional self-calibration method, the wavefronts in the zeroth-order diffracted beam and the first-order diffracted beams observed by a Fizeau interferometer arranged in the Littrow configuration were employed to evaluate the pitch deviation of a scale grating. The arithmetic operation with the wavefront data realizes the evaluation of the pitch deviation over a large area in a short time, while cancelling the influence of the out-of-flatness of a scale grating. Meanwhile, theoretical equations in the conventional self-calibration method cannot be directly applied to the evaluation of a VLS grating due to its unique properties of the pitch distribution. In this paper, major modifications are thus made to the conventional theoretical equations for deriving the pitch distribution of a VLS grating. To verify the performance of the newly proposed method, the pitch distribution of a VLS grating employed in a commercial planar absolute encoder is evaluated in experiments.</jats:p>
Journal
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- Measurement Science and Technology
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Measurement Science and Technology 32 (6), 064005-, 2021-04-14
IOP Publishing
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Details 詳細情報について
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- CRID
- 1360294643803062656
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- ISSN
- 13616501
- 09570233
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- Data Source
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- Crossref
- KAKEN