System and method for determining the alignment quality in an illumination system that includes an illumination modulator
First Claim
1. An alignment detection system for determining whether a modulated illumination field in an imaging system employing an illumination modulator is mis-aligned, said alignment detection system comprising:
- modulator adjustment means for providing a test pattern on the illumination modulator;
a detector for receiving a modulated illumination field from said illumination modulator;
sampling means for determining at least two sample values (A and C) for each of two areas of said modulated illumination field respectively; and
evaluation means for determining whether the value |A−
C| is greater than a threshold value.
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Accused Products
Abstract
An alignment detection system is disclosed for determining whether a modulated illumination field in an imaging system employing an illumination modulator is mis-aligned. The alignment detection system includes a modulator adjustment unit for providing a test pattern on the illumination modulator, a detector for receiving a modulated illumination field from the illumination modulator, a sampling unit for determining at least two sample values (A and C) for each of two areas of the modulated illumination field respectively, and an evaluation unit for determining whether the value |A−C| is greater than a threshold value.
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Citations
16 Claims
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1. An alignment detection system for determining whether a modulated illumination field in an imaging system employing an illumination modulator is mis-aligned, said alignment detection system comprising:
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modulator adjustment means for providing a test pattern on the illumination modulator; a detector for receiving a modulated illumination field from said illumination modulator; sampling means for determining at least two sample values (A and C) for each of two areas of said modulated illumination field respectively; and evaluation means for determining whether the value |A−
C| is greater than a threshold value. - View Dependent Claims (2, 3, 4, 5)
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6. An alignment detection system for determining whether a modulated illumination field in an imaging system employing an illumination modulator is mis-aligned, said alignment detection system comprising:
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modulator adjustment means for providing a periodic alternating test pattern on the illumination modulator; a detector for receiving a modulated illumination field from said illumination modulator; sampling means for determining at least two average sample values (A, B and C) for each of two areas of said modulated illumination field respectively; and evaluation means for determining whether one of the values |A−
B|, |A−
C|, or |B−
C| is greater than a threshold value. - View Dependent Claims (7, 8, 9, 10)
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11. A method of detecting whether a modulated illumination field in an imaging system is mis-aligned, said method comprising the steps of:
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providing a test pattern on the illumination modulator; receiving a modulated illumination field from said illumination modulator at a detector; determining at least two sample values (A and C) for each of two areas of said modulated illumination field respectively; and determining whether the value |A−
C| is greater than a threshold value. - View Dependent Claims (12, 13, 14, 15)
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16. An error detection system for determining whether a modulated illumination field in an imaging system employing an illumination modulator is in error, said error detection system comprising:
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modulator adjustment means for providing a test pattern on the illumination modulator; a detector for receiving a modulated illumination field from said illumination modulator; sampling means for obtaining a plurality of sample values of said modulated illumination field; and evaluation means for determining an overall alignment quality by comparing a width of a histogram generated by the plurality of sample values with a threshold value.
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Specification