Patent ID: 6428171
Filing Date: 2002-08-06
Classification: G01B

Abstract:
A height measuring apparatus comprising:an illumination optical system having an objective lens for focusing measuring light on a surface of an object; two-dimensional scanning means for scanning the object in two directions, with the measuring light; a pupil relay lens system for projecting a pupil plane of the objective lens to a pupil projection plane; an imaging optical system provided in the pupil projection plane having an optical axis spaced by a predetermined distance from an optical axis of the pupil projection plane and configured to converge some of light beams reflected from the object; an optical position-detecting device arranged in a focusing plane of the imaging optical system, for detecting a distance of a light spot that has moved in accordance with a height of the object; and a height calculator for calculating the height of the object from position data supplied from the optical position-detecting device.