Virtual zoom lens
A method of edge detection with an optical measuring machine including aligning a test object with a lens system having a variable size aperture, wherein the lens system is operable to form an image of the test object on a digital sensor having an array of addressable pixels, and wherein the variable size aperture is operable to image points of the test object on the digital sensor at different spot sizes. Setting the variable size aperture to a first size and binning contiguous clusters of the addressable pixels into image pixels having a first size in accordance with the number of addressable pixels within each of the image pixels. Identifying contrast variations of the test object imaged onto the digital detector over a number of image pixels at the variable aperture first size, whereby an area of the test object is imaged at a first effective magnification.
1 . A method of edge detection with an optical measuring machine, comprising:
aligning a test object with a lens system operable to form an image of the test object on a digital sensor having an array of addressable pixels, and wherein the lens system is operable to image points of the test object on the digital sensor at different spot sizes;
setting the lens system to a first spot size;
binning contiguous clusters of the addressable pixels to image pixels having a first size in accordance with the number of addressable pixels within each of the image pixels;
identifying contrast variations of the test object imaged onto the digital sensor over a number of image pixels at the first spot size, whereby an area of the test object is imaged at a first effective magnification.
2 . The method of edge detection according to claim 1 , further comprising setting the lens system to a second spot size, binning contiguous clusters of the addressable pixels to image pixels having a second size in accordance with the number of addressable pixels within each of the image pixels, and identifying contrast variations of the test object imaged onto the digital sensor over substantially the same number of image pixels at the lens system second spot size as at the lens system first spot size, whereby an area of the test object is imaged at a second effective magnification.
3 . The method of edge detection according to claim 2 , wherein the lens system is adjusted at each magnification to maintain substantially the same number of image pixels within each spot size.
4 . The method of edge detection according to claim 2 , wherein the steps of identifying the contrast variations of the test object include imaging the test object on a visual display, and the different size image pixels image the test object at different magnifications.
5 . The method of edge detection according to claim 2 , wherein the step of setting the lens system to the second spot size decreases an f-number of the lens system and decreases a spot size at which the test object is imaged on the digital sensor, and the step of binning contiguous clusters of the addressable pixels to image pixels having a second size reduces the image pixels in size in accordance with a smaller spot size at which points of the test object are imaged.
6 . The method of edge detection according to claim 5 , wherein the step of binning contiguous clusters of the addressable pixels of the digital sensor reduces the size of the image pixels to substantially maintain the size of the image pixels as a given fractional portion of a spot size at which points of the test object are imaged.