Method and system for surface contouring
First Claim
1. A surface contouring system comprising:
- means for projecting a sinusoidal pattern on a surface to be tested;
means for shifting the pattern in three steps at one quarter period intervals of the sinusoidal pattern;
mask means containing the same sinusoidal pattern;
at least one detector for sensing, through said mask means, the intensity of the radiation from the test surface;
means for scanning each said detector at each step to obtain from each detector a signal representative of the level of intensity at each detector;
means for storing each intensity level derived from each detector at each of said steps;
means responsive to said storing means for determining the d.c. spatial frequency amplitude from the sum of the intensity levels derived from the first and third steps;
for determining the cosinusoidal spatial frequency amplitude from the difference between the intensity levels derived from the first and third steps and for determining the sinusoidal spatial frequency amplitude and intensity level derived from the second step;
means for combining said sinusoidal and cosinusoidal spatial frequency amplitudes to generate an amplitude representative of a trigonometric function of the phase angle of the radiation from the test surface; and
means, responsive to said amplitude representative of a trigonometric function of the phase angle, for generating an output representative of the height of the test surface at each position monitored by a said detector.
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Abstract
A method and system for surface contouring including: projecting a sinusoidal pattern on a surface to be tested; shifting the pattern in three steps at one-quarter period intervals of the sinusoidal pattern; sensing the intensity of the radiation from the test surface through a mask containing the same sinusoidal pattern at at least one position of the surface at each of the steps; storing the intensity sensed at each position at each step; for each of the positions adding the intensity of the first and third steps to produce a d.c. spatial frequency amplitude, subtracting the intensity of the third step from that of the first to obtain the cosinusoidal spatial frequency amplitude, and subtracting the intensity of the second step from the d.c. amplitude to produce the sinusoidal spatial frequency amplitude; combining the sinusoidal and cosinusoidal amplitudes to produce a trigonometric function of the phase angle of the projected sinusoidal pattern on the test surface and generating from the trigonometric function of the phase angle an output representative of the height of the surface at each position.
81 Citations
14 Claims
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1. A surface contouring system comprising:
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means for projecting a sinusoidal pattern on a surface to be tested; means for shifting the pattern in three steps at one quarter period intervals of the sinusoidal pattern; mask means containing the same sinusoidal pattern; at least one detector for sensing, through said mask means, the intensity of the radiation from the test surface; means for scanning each said detector at each step to obtain from each detector a signal representative of the level of intensity at each detector; means for storing each intensity level derived from each detector at each of said steps; means responsive to said storing means for determining the d.c. spatial frequency amplitude from the sum of the intensity levels derived from the first and third steps;
for determining the cosinusoidal spatial frequency amplitude from the difference between the intensity levels derived from the first and third steps and for determining the sinusoidal spatial frequency amplitude and intensity level derived from the second step;means for combining said sinusoidal and cosinusoidal spatial frequency amplitudes to generate an amplitude representative of a trigonometric function of the phase angle of the radiation from the test surface; and means, responsive to said amplitude representative of a trigonometric function of the phase angle, for generating an output representative of the height of the test surface at each position monitored by a said detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of surface contouring comprising:
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projecting a sinusoidal pattern on a surface to be tested; shifting the pattern in three steps at one-quarter period intervals of the sinusoidal pattern; sensing the intensity of the radiation from the test surface through a mask containing the same sinusoidal pattern at at least one position of the surface at each of said steps; storing the intensity sensed at each position at each step; for each of said positions, adding the intensity at the first and third steps to produce the d.c. spatial frequency amplitude, subtracting the intensity at the third step from that at the first to obtain the cosinusoidal spatial frequency amplitude and subtracting the intensity at the second step from the d.c. amplitude to produce the sinusoidal spatial frequency amplitude; combining the sinusoidal and cosinusoidal amplitudes to produce a trigonometric function of the phase angle of the radiation from the test surface; and generating from the trigonometric function of the phase angle an output representative of the height of the surface at each position. - View Dependent Claims (14)
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Specification