Expansion of phase uniqueness of projection methods when illuminated by sinusoidal pictures with different periods
The article describes a method for eliminating phase ambiguity in the use of a series of measurements with different periods. The choice of the period of sinusoidal patterns with given periods can be carried out using the structured illumination of the object. The phase information is obtained...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Omsk State Technical University, Federal State Budgetary Educational Institution of Higher Education
2019-03-01
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| Series: | Омский научный вестник |
| Subjects: | |
| Online Access: | https://www.omgtu.ru/general_information/media_omgtu/journal_of_omsk_research_journal/files/arhiv/2019/1%20(163)/43-49%20%D0%93%D1%83%D0%B6%D0%BE%D0%B2%20%D0%92.%20%D0%98.,%20%D0%9C%D0%B0%D1%80%D1%87%D0%B5%D0%BD%D0%BA%D0%BE%20%D0%98.%20%D0%9E.,%20%D0%9F%D0%BE%D0%B7%D0%B4%D0%BD%D1%8F%D0%BA%D0%BE%D0%B2%20%D0%93.%20%D0%90.%20%D0%B8%20%D0%B4%D1%80..pdf |
| Summary: | The article describes a method for eliminating phase ambiguity
in the use of a series of measurements with different periods.
The choice of the period of sinusoidal patterns with given
periods can be carried out using the structured illumination
of the object.
The phase information is obtained by the stepwise phase shift
method. For this, three or more sinusoidal patterns with a given phase shift are projected onto the object. As a result
of the decoding of the intensity patterns recorded, a field of
phase quantities is obtained with a period determined by the
magnitude of the period of the projected sinusoidal pattern.
The same phase distribution can also be obtained with a
different period.
As a result of subtraction of phase pictures, the period of
difference will be greater than the initial periods. The
resulting period is determined by the equivalent period. The
value of the equivalent period is inversely proportional to
the difference of the initial periods. To increase the region
of phase uniqueness, it is necessary to choose close periods.
However, in this case, the error in determining the profile
increases.
The method proposed in the article obtains three or more
series of sinusoidal pictures with different periods for
illuminating the object. Reduction in error is provided by
combining the phase values obtained for a minimum period
with the values of phase transitions for the extended range,
which allows to eliminate the effect of increasing the error
and, accordingly, to reduce the overall phase error. Areas
of phase transitions are automatically determined as a result
of subtraction of the profile of the object obtained during
measurements with different periods. Since the regions of
phase transitions are homogeneous, we can propose a simple
averaging procedure. Adding to the obtained field of phase
transitions the measurement results with a minimum period,
we obtain measurements with a minimum error. In this case,
the periods of projected pictures do not need to be close.
This choice of periods ensures the stability of the proposed
method. |
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| ISSN: | 1813-8225 2541-7541 |