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|Title: ||Zone plate interferometers for verifying three coordinate measuring machines|
|Authors: ||Stevens, Richard F.|
|Issue Date: ||1985|
|Publisher: ||© R. F. Stevens|
|Abstract: ||This thesis is concerned with the use of zone plate interferometers for
the precise location of position. The thesis begins by discussing the
use of the zone plate as an optical component and examines the
wavefront aberrations that can occur in higher orders of diffraction.
Interferometers applicable to the measurement of position are then
reviewed, including interferometers that incorporate optical zone
plates as beam dividers and beam combiners.
A zone plate interferometer for defining and locating multiple
positions in three-dimensions is reported. Here, a three-dimensional
array of positions is defined by a two-dimensional array of reflective
zone plates. An optical probe containing two zone plates completes the
interferometer, and is used to locate the positions.
The displacement sensitivity of the probe can be controlled at the
optical design stage. The variation of sensitivity with wavefront
geometry is explored and expressions are derived for the transverse and
axial sensitivity in terms of the conjugates of the illuminating
wavefronts. Various wave front configurations were experimented with and
the resulting position location patterns recorded. The measured values
of sensitivity to displacement are compared to theory.
A version of this interferometer was designed and developed by the
author, for checking the performance of three-coordinate measuring
machines used in engineering metrology. The results of trials with the
interferometer, comparing the performance of measuring machines in
several government laboratories, are reported. The averaged
repeatability of setting, on one optically defined position, was found
to be 1 µm in the transverse directions and 6 µm in the axial
Resulting from this work, two simple devices for pointing are
described. Each uses a pair of zone plates to define an optical axis.
In one case, the axis is precisely located by positioning a coherent
light source and observing the interference bands generated by the
device. In the other, moire bands are observed in incoherent
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Physics)|
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