Patent ID: 6452686
Filing Date: 2002-09-17
Classification: G01B,G01N,G02B

Abstract:
A high speed method of axially translating a focus position of an illumination beam along an optical axis relative to at least one object positioned within a depth range, the method comprising:dividing a predetermined range of axial motion of the focus position into a coarse range and a narrow range, the coarse and narrow ranges being based upon a depth variation of the at least one object relative to a depth of focus of the illumination beam; coarse positioning the illumination beam within the coarse range by relatively translating an optical head and the at least one object; fine positioning the illumination beam within the narrow range so as to translate the focus position along the optical axis during relative motion within the coarse range, the step of fine positioning including varying the focus of the illumination beam at a rate substantially greater than a rate of coarse positioning with the coarse range, whereby the speed of a system utilizing the method is improved with a reduction in mechanical motion requirements.