Non-contact optical apparatus for measuring the length or speed of a relatively moving surface
First Claim
1. A non-contact optical measurement apparatus for measuring the length or speed of a solid surface in relative motion with the apparatus comprising:
- means for producing an optical interference pattern on the surface;
means for receiving modulated light reflected from the surface; and
signal processing means coupled to the receiving means, the signal processing means including converter means for converting the modulated light to a pulse train, detector means for detecting a break in the sequence of pulses in the pulse train, correction means for adding pulses to the pulse train during the break in the pulse sequence, and indicator means for indicating the length of the surface or the speed of the relative motion as a function of the corrected pulse train.
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Accused Products
Abstract
The apparatus generates two optical beams which are directed to a relatively moving solid surface where an interference pattern, having substantially parallel fringes, is formed. The light is scattered and thereby modulated by irregularities on the surface. This modulated light is received and the signal is processed to indicate the length of the surface or its relative speed. The signal processor converts the modulated light signal to a pulse train, and adds pulses to the pulse train when a drop-out in the signal is detected, i.e. when the time between pulses in the pulse train is greater than a factor times the average period of the pulse train. The corrected pulse train is a function of the length of the surface or the relative motion between the apparatus and the surface.
26 Citations
6 Claims
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1. A non-contact optical measurement apparatus for measuring the length or speed of a solid surface in relative motion with the apparatus comprising:
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means for producing an optical interference pattern on the surface; means for receiving modulated light reflected from the surface; and signal processing means coupled to the receiving means, the signal processing means including converter means for converting the modulated light to a pulse train, detector means for detecting a break in the sequence of pulses in the pulse train, correction means for adding pulses to the pulse train during the break in the pulse sequence, and indicator means for indicating the length of the surface or the speed of the relative motion as a function of the corrected pulse train. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification