The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 08, 1980
Filed:
Dec. 13, 1978
N Balasubramanian, Cupertino, CA (US);
Other;
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.