Patent ID: 7145659

Claim:
A light interference measurement method using a computer-generated hologram, comprising: splitting light from a coherent light source into two light beams; irradiating a reference surface with a first light beam of said light beams to obtain reflected light from this reference surface as reference light; irradiating a sample surface of a object with a second light beam via a computer-generated hologram to obtain reflected light from said sample surface as object light; and measuring the surface shape of said sample surface on the basis of interference fringes obtained by light wave interference between said reference light and said object light, the measurement method further comprising: holding said computer-generated hologram by a retaining member so that said computer-generated hologram adopts an attitude with respect to an alignment light beam, and so that said computer-generated hologram is disposed in a predetermined position; holding said object on a substrate; performing relative positioning of said computer-generated hologram and said sample surface by interposing a spacer between said retaining member and said object or said substrate; and subsequently measuring the surface shape of said sample surface by causing said second light beam to be incident on said computer-generated hologram at a predetermined angle of inclination.