Abstract: In the magneto-optic recording/reproduction apparatus, a light beam from a semiconductor laser that can be used with two wavelengths, for recording and reproduction is converged by an objective lens on a magneto-optic disk, a predetermined offset is added to this focusing error signal by an offset adjusting circuit, and the objective lens is driven in the direction of the optical axis based on the focusing error signal to which an offset was added.

Abstract: An optical system of an optical disk apparatus having plural optical elements characterized in that the optical element having aberration which can counterbalance the wave front aberration of the whole optical system is disposed, or a direction of aberration of each existing optical element is adjusted in order to correct the wave front aberration.

Abstract: A signal detecting apparatus in an optical disc apparatus having an objective lens which converges light emitted from a light source onto an optical disc and a condenser lens which converges light reflected by the optical disc and transmitted through the objective lens includes first and second light receiving elements, each having a light receiving surface located before or behind a convergence point on which the light reflected from the optical disc is converged when the objective lens is in a focal position. Each of the light receiving surfaces are split into at least four light receiving areas.

Abstract: An apparatus for measuring the deviation from a specific position of a mirror surface, includes an auto collimating system in which a point light source is located at a reference point on a reflecting surface of the mirror surface located at a predetermined correct position. A light emitter emits detecting light onto the point light source from an incident optical axis inclined with respect to a normal of the mirror surface. A position detector measures the deviation of the detecting light reflected by the mirror surface and reciprocally transmitted through the auto collimating system and again reflected by the mirror surface.

Abstract: An optical axis adjusting apparatus is provided and includes a laser beam source, a beam shaping prism for shaping a laser beam of elliptical flux emitted from the laser beam source into a laser beam of circular flux, and an angle adjusting device which adjusts the angular direction of the outgoing laser beam emitted from the shaping prism.

Abstract: A mechanism for adjusting an optical axis of an optical device, particularly in an optical information recording and reproducing system, in accordance with which the optical axis is movable in two directions, independently of each other. Various parts of the optical system, such as an anamorphic prism and a fixed prism, may be moved to adjust the degree of parallelism and/or displacement of a laser beam. A laser ray source in the system also may be movable independently in different directions.

Abstract: A compound prism including a plurality of unit prisms which have reflective interfaces defined by outer and/or inner surfaces thereof and which are arranged so that light is reflected by an inner surface of the interface of one of the unit prisms and by an outer surface of the interface of another unit prism.

Abstract: A roof surface measuring method including the making of a collimated bundle of rays incident upon roof surfaces at a predetermined incident angle, laterally displacing a part of the wavefront reflected by the roof surfaces in a direction parallel with an edge line defined by the intersection of the roof surfaces by a displacing means, and making the laterally displaced wavefront and the original wavefront incident upon a measuring surface in a manner which causes an interference therebetween. The invention is also directed to a measuring apparatus for effecting the method.

Abstract: An apparatus for measuring a wave front aberration including a light beam splitter for dividing a parallel laser light beam incident from a measuring object into two beam fluxes, an image rotator disposed in at least one optical path of the divided beam fluxes for rotating the wave from on the optical axis, an interference device for interfering, after superposing the beam fluxes, whose wave fronts are rotated relatively, an imaging lens for forming the interfered beam into an image, and an observation device for observing the imaged interference fringes.

Abstract: A method of measuring a refractive index distribution of a lens is disclosed which comprises, immersing a glass sample and a lens under test within a matching fluid whose refractive index differs slightly from that of the glass to be tested, the glass sample having a refractive index and a shape which are both known and the lens to be tested having an unknown refractive index but a known shape, allowing coherent light to pass through the glass sample and the lens under test; superposing the transmitted light wave on a reference light wave to generate interference fringes, outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through the glass sample, determining the refractive index of the matching fluid on the basis of the resulting output, outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through the lens under test; separating from the resulting output the defocus term and aberratio

Abstract: An apparatus for measuring the profile of an aspherical surface in which two coherent optical beams of closely spaced frequencies are produced. One of the beams is reflected from either an optical probe or a mechanical feeler probe coupled with the turning aspherical surface. The reflected and non-reflected beams interfere and the resultant beat signal is detected and its frequency change measured to determine the differing optical path length to the turning aspherical surface. The mechanical probe has a feeler biased into contact with the aspherical surface and a reflector fixed thereto for reflecting the one beam. The optical probe has an auto-focusing objective lens for focusing the one beam to be reflected from the turning asperical surface.