Abstract: A projection exposure apparatus of the type which employs an alignment light of the same wavelength as an exposure light and includes an optical system subjected to correction of chromatic aberration for the exposure light so as to simultaneously observe an alignment area on a reticle and an alignment area on a photosensitive substrate to bring the reticle and the photosensitive substrate into alignment. The apparatus includes light source means for emitting light of a wavelength different from that of the exposure light and capable of sensitizing the photosensitive substrate, and optical means for introducing the light source means into the optical system to project it on to the alignment area on the photosensitive substrate through the alignment area on the reticle.

Abstract: An apparatus includes a means for providing a predetermined frequency difference between two light beams and generating an optical beat with respect to interference between first and second diffracted light beams from a diffraction grating formed on a substrate, and a means for detecting a phase difference between the optical beat and a reference signal having a frequency corresponding to the frequency difference between the two light beams, and detects a position of the substrate based upon the phase difference in accordance with an optical heterodyne interference method.

Abstract: A focusing screen in a split image coincidence type range finder provided with an objective lens forming an imaging plane comprises a plurality of light diffusing portions each of which has a surface inclined with respect to the imaging plane. A number of minute depressions or projections are formed on the inclined surface. The depressions or projections are arranged in the form of a matrix along a first direction and a second direction intersecting each other and symmetrical with respect to a fixed direction parallel to the inclined surface and the imaging plane. Each of the depressions or projections is of a pyramidic shape having as the base a parallelogram having first and second sides parallel to the first direction and third and fourth sides parallel to the second direction and extended in the fixed direction. Each of the depressions or projections is arranged so that each side of the parallelogram is common to a side of another adjacent parallelogram.