Reticle and analysis methods to improve autocollimator accuracy and reduce measurement error
OwnerDennis Mikkelsoninventor
Life of this patent
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Abstract
Reticles, autocollimators, systems, and methods for measurement of angles including a reticle having at least one line which produces a line image on a sensor where the line image is mismatched with respect to vertical and horizontal reference lines of pixels of the sensor such that periodic measurement error due to regular spacing between pixels is reduced or eliminated. In aspects an autocollimator includes a reticle comprising a pattern having a first line with a slope and a second line with an inverse of the slope, the lines being other than parallel.
Claims32
A method of reducing period error in measurement of light intensity associated with an area sensor having an array of pixels arranged in rows and columns defining vertical and horizontal reference lines, the periodic error due to sampling of an image on the array of pixels, the method comprising:
- providing a reticle having a pattern such that light passing through the reticle forms a light pattern on the pixels of the area sensor in the form of the pattern or inverse of the pattern;
- and
- orienting the reticle such that the pattern includes or defines at least one non-vertical non-horizontal line segment whereby combining measurements of the light intensity of pixels associated with the light pattern of the at least one line segment reduces the periodic error.
A device, comprising:
- an area sensor having an array of pixels arranged in rows and columns defining vertical and horizontal reference lines and producing a periodic error due to sampling of an image on the array of pixels;
- and
- a reticle having a pattern such that light passing through the reticle forms a light pattern on the pixels of the area sensor in the form of the pattern or inverse of the pattern, the reticle oriented such that the pattern includes or defines at least one non-vertical non-horizontal line segment whereby combining measurements of light intensity of pixels associated with the light pattern of the at least one line segment reduces the periodic error.
A reticle for use with an area sensor having an array of pixels arranged in rows and columns defining vertical and horizontal reference lines and producing a periodic error due to sampling of an image on the array of pixels, the reticle comprising:
- a transparent base having a pattern such that light passing through the base forms a light pattern on the area sensor in the form of the pattern or inverse of the pattern, the pattern includes at least two line segments having respective slopes of +/−n and −/+1/n where n is a positive real number, and if the two line segments are perpendicular, the pattern also includes another line segment with slope −/+n or +/−1/n.
A method of establishing a position of a center point of a reticle image caused by projecting light through a reticle onto an area image sensor, the sensor having an array of pixels arranged in rows and columns defining vertical and horizontal reference lines and producing a periodic error due to sampling of the reticle image on the array of pixels, the method comprising:
- determining an equation of a first line corresponding to light projected from a first line segment of the reticle onto pixels of the image sensor, the first line segment of the reticle being a non-vertical non-horizontal line segment whereby combining measurements of light intensity from the pixels associated with the light projected from the first line segment reduces the periodic error;
- determining an equation of a second line corresponding to light projected from a second line segment of the reticle onto pixels of the image sensor, the second line segment of the reticle being a non-vertical non-horizontal line segment whereby combining measurements of light intensity from the pixels associated with the light projected from the second line segment reduces the periodic error;
- and
- analyzing the equation of the first line and the equation of the second line to determine an intersecting point of the lines to establish a position of the center point of the reticle image upon the sensor.
Dependencies are inferred from the claim text.