Abstract: In a method for evaluating the homogeneity of the refractive index of an optical member, the refractive index distribution of the optical member is measured, the measured refractive index distribution is separated into a rotationally symmetric element and a non-rotationally symmetric element in the optical axis direction before or after correction of the power element, and the rotationally symmetric element is further subjected to 2nd/4th-order element correction. Upon execution of such comprehensive evaluation, a photolithography optical member, which can realize a fine, sharp exposure-transfer pattern (e.g., a line width of 0.3 &mgr;m or less) is provided.

Abstract: In a method for evaluating the homogeneity of the refractive index of an optical member, the refractive index distribution of the optical member is measured, the measured refractive index distribution is separated into a rotationally symmetric element and a non-rotationally symmetric element in the optical axis direction before or after correction of the power element, and the rotationally symmetric element is further subjected to 2nd/4th-order element correction. Upon execution of such comprehensive evaluation, a photolithography optical member, which can realize a fine, sharp exposure-transfer pattern (e.g., a line width of 0.3 .mu.m or less) is provided.

Abstract: Wavefront aberration-measuring apparatus are disclosed that can easily and accurately correct interference-fringe distortions arising from aberrations of an optical system in an interferometer and that can reduce wavefront aberration-measurement errors arising from such distortion. The apparatus comprise an interferometer that forms an interference fringe from a synthesis of a wavefront of light reflecting from a reference surface and a wavefront of light from a test object (such as a reflective surface or lens). The apparatus also comprises an image-pickup element for detecting the interference fringe, and an arithmetical calculator that calculates the wavefront aberration between the test object and the reference surface based on an output from the image-pickup element. Between the test object and the image-pickup element is an optical system (e.g., converging lens) that transmits a wavefront that is perpendicularly incident to a surface of the test object.

Abstract: An oil ring set has an expander between upper and bottom side rails for a piston of a reciprocal internal combustion engine. The oil ring set has dimensions determined so as to have a thickness satisfying a first relationship between a radial thickness and tension determined from a coefficient for an oil film thickness and a standard parameter representative of a predetermined thickness, a second relationship between a radial thickness and tension determined from a coefficient for an oil ring propensity to follow deformation and its pattern of the cylinder wall and a standard parameter representative of a predetermined amount of oil consumption, and a third relationship between a radial thickness and tension determined based on a coefficient representative of permanence of oil ring springiness against swelling and a standard parameter of the coefficient of springiness permanence.

Abstract: Amounts of variation of data representing the shape of an abutment tooth are determined, and a train of points is extracted from the amounts of variation. Then a developed view of the surface shape of the abutment tooth is displayed, and the obtained train of points is also displayed in the developed view. The margin line for designing the artificial crown is determined, based on thus displayed train of points.

Abstract: A contour measuring apparatus comprises a laser measurement unit, a mount table for mounting an object, a motor for rotating the mount table around an axis, an altering jig for supporting the mount table and the motor and altering a direction of the axis with respect to the laser measurement unit, and a drive table for supporting the altering jig and driving the altering jig to alter a position of the mount table with respect to the laser measurement unit.