Method for estimating the accuracy of an optical distance measuring probe
First Claim
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1. A method for estimating the accuracy of a set of distance measurements to a workpiece, the distance measurements obtained by steps including illuminating successive locations along the workpiece, comprising:
- (a) computing a power spectrum of the distance measurements;
(b) selecting a cutoff index; and
(c) inferring the accuracy of the measurements from said power spectrum at indices above said cutoff index.
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Abstract
A method for estimating the error of a measured shape of a workpiece, as measured using an optical probe. A series of N equally spaced distance measurements are transformed to a power spectrum. The average power above a cutoff index is divided by N to give an estimate of the variance of the shape measurement.
2 Citations
4 Claims
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1. A method for estimating the accuracy of a set of distance measurements to a workpiece, the distance measurements obtained by steps including illuminating successive locations along the workpiece, comprising:
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(a) computing a power spectrum of the distance measurements;
(b) selecting a cutoff index; and
(c) inferring the accuracy of the measurements from said power spectrum at indices above said cutoff index. - View Dependent Claims (2, 3, 4)
(i) computing a variance of said power spectrum at a set of indices below a Nyquist index;
(ii) adding successively lower indices to said set; and
(iii) for each said successively lower index, computing said variance of said power spectrum of said set;
said cutoff index being said successively lower index whereat said computed variance first changes significantly relative to an immediately preceding said computed variance.
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4. The method of claim 3, wherein said set initially includes indices between three-quarters of said Nyquist index and said Nyquist index.
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Current AssigneeNextec Technologies 2001 Ltd. (Han's Laser Technology Industry Group Co., Ltd.)
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Original AssigneeNEX Tec Limited
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InventorsBunimovich, David, Horovitz, Gabi
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Primary Examiner(s)RAEVIS, ROBERT R
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Application NumberUS09/213,772Time in Patent Office796 DaysField of Search73/1.79, 73/1.81, 356/376US Class Current73/1.81CPC Class CodesG01B 11/026 by measuring distance betwe...
