Abstract: A method of analyzing interference fringes for use in a holographic interferometry process for measuring, by using a computer generated hologram, the shape of an object to be examined. The method comprises:a first step of obtaining a wave surface (xl, yl, zl) of a surface to be measured from measurement interference fringes;a second step of obtaining a coefficient A.sub.k relative to the wave surface (xl, yl, zl) of the surface, from a coefficient a.sub.ij of a series of the object wave which has been obtained based on the hypothesized coordinates on a computer hologram at the time when the computer generated hologram is made, and from a coefficient b.sub.ij of a series of the object based on the hypothesized coordinates on the object, the coefficient A.sub.k minimizing the square sum or the maximum value of a function of Xl, Yl, Zl, and a third step of obtaining a shape error from the ideal shape of the object by calculating the function on the basis of the A.sub.k.

Abstract: A holographic interferometer comprising a source of laser beams, a condenser lens for converging a laser beam supplied from said laser-beam source, a pinhole which allows the passage of said converged laser beam, a collimator lens having a focal point which lies on said pinhole, a beam splitter disposed in an inclined manner between said pinhole and said collimator lens, a spacial filter disposed on the optical axis of a light reflected from said beam splitter and at an optically conjugate position relative to said pinhole, and a hologram standard disposed between said spacial filter and said beam splitter.

Abstract: A holographic interferometer comprising a source of laser beams, a condenser lens for converging a laser beam supplied from said laser-beam source, a pinhole which allows the passage of said converged laser beam, a collimator lens having a focal point which lies on said pinhole, a beam splitter disposed in an inclined manner between said pinhole and said collimator lens, a spacial filter disposed on the optical axis of a light reflected from said beam splitter and at an optically conjugate position relative to said pinhole, and a hologram standard disposed between said spacial filter and said beam splitter.