Patent ID: 7158690

Claim:
A method of measuring lengths at a greater resolution than a resolution offered by an image capturing system, said method comprising: capturing in said image capturing system, a first image of a first scale overlapping with a second scale, wherein said first scale has a first pitch and said second scale has a second pitch, wherein said first pitch is not equal to said second pitch, said first pitch determined by a width of each of said first plurality of bands and said second pitch determined by a width of each of said second plurality of bands, further comprising storing data representing a plurality of configuration bit patterns, wherein each of said plurality of configuration bit patterns represents a corresponding one of a plurality of configurations, wherein each of said plurality of configurations represents a different offset of said first scale with respect to said second scale and said first scale contains a first plurality of bands and said second scale contains a second plurality of bands, each of said first plurality of bands being of a first width and each of said second plurality of bands being of a second width, wherein said first width is not equal to said second width; moving said first scale relative to said second scale by a distance; capturing in said image capturing system, a second image of said first scale overlapping with said second scale after said moving; and examining, using a digital processing system, said first image and said second image to determine a length of said distance, wherein said examining comprises receiving in said digital processing system a first bit pattern and a second bit pattern based on said first image and said second image, comparing said first bit pattern and said second bit pattern with said plurality of configuration bit patterns to determine a first configuration and a second configuration respectively, wherein offsets associated with said first configuration and said second configuration are used to determine said length.