Patent ID: 7791008

Claim:
A method for focusing a color imager having an imager field of view, an imager optical axis and an imager focal plane comprising: placing an object of interest in front of said color imager; emitting a focusing light beam at a beam angle relative to said imager optical axis that intersects said imager focal plane within said imager field of view at an imager focal point, onto said object of interest to create a focusing light spot; acquiring a color image of said focusing light spot on said object of interest using said imager, wherein said color image has at least two color bands and has pixels with pixel values near saturation for at least one of said color bands; mapping pixels having pixel values near saturation in a first color band to provide a pixel map of said focusing light spot in said first color band; setting a threshold for pixel values in a second color band in said pixel map, whereby pixels brighter than said threshold in said second color band can be determined, resulting in brightest pixels; determining a center of mass to determine the center of said brightest pixels; determining a pixel difference between said center of said brightest pixels and said imager focal point; obtaining a range adjustment based on said pixel difference; and moving said imager according to said range adjustment to minimize said pixel difference.