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US 4,836,681 AGranted
Fringe pattern phase detection system
AssigneeLockheed Electronics Co., Inc.
InventorsJohn G. Van Saders, Andrew Tarasevich, Michael C. Reichenbach
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AssigneeLockheed Electronics Co., Inc.
InventorsJohn G. Van Saders, Andrew Tarasevich, Michael C. Reichenbach
Estimating the term…
Electro-optical apparatus measures the average relative phase of an incident wave fringe pattern. The subject fringe, e.g., an interferometric pattern, passes through three sections of an optical mask, one characterized by fixed transmissivity and the other two by quadrature-displaced spatial fringe patterns. The light passing through each section is separately collected and detected to average the respective incident wave/mask section interactions. The phase of the incident fringe pattern relative to the mask is then determined by arithmetically processing the detected signals. In accordance with one aspect of the present invention, the subject fringe pattern is time modulated and the quadrature-shifted mask signals A-C coupled to obviate the requirement for the third, fixed transmissivity mask section.
In combination in apparatus for detecting the phase of an incident light fringe pattern, first and second mask means each having an alternating array of light passing and light blocking area corresponding to the incident light fringe patterns, the light passing and blocking array of said second mask means being quadrature offset with respect to the array of said first mask means, first and second light detectors, and averaging light collecting means disposed intermediate said first and second mask means and said first and second light detectors for coupling the fringe pattern light passing through said first and second mask means onto said first and second light detectors, respectively;
In combination in apparatus for detecting the phase of an incident light fringe pattern, first and second mask means each having an alternating array of light passing and light blocking areas corresponding to the incident light fringe patterns, the light passing and blocking array of said second mask means being quadrature offset with respect to the array of said first mask means, first and second light detectors, and averaging light collecting means disposed intermediate said first and second mask means and said first and second light detectors for coupling the fringe pattern light passing through said first and second mask means onto said first and second light detectors, respectively, and third mask means characterized by constant light transmissivity, a third light detector, said light collecting means further including means for transmitting light passing through said third mask means to said third light detector, and subtracting means connected to said first, second and third light detectors.
In combination in apparatus for multiplying two complex quantities, light fringe pattern supplying means, first and second mask means each having an alternating array of light passing and light blocking areas corresponding to the incident light fringe patterns, the light passing and blocking array of said second mask means being quadrature offset with respect to the array of said first mask means, first and second light detectors, and averaging light collecting means disposed intermediate said first and second mask means and said first and second light detectors for coupling the fringe pattern light passing through said first and second mask means onto said first and second light detectors, respectively, said light fringe pattern supplying means including acoustically modulated light transmitting means, first complex signal dependent signal source means for modulating said acoustically modulated light transmitting means, a light source irradiating said acoustically modulated light transmitting means, and second complex signal dependent means for modulating the light supplied by said light source means.
Dependencies are inferred from the claim text.