Abstract: An inclination angle detector electrically detects an angle of inclination of an object of measurement with respect to the horizontal direction or the direction of gravitation. An inclination angle detector includes a bubble tube having a transparent container formed such that the inner surface of an upper part thereof has a spherical concave surface. The transparent container has a gas and a transparent liquid sealed therein. A light-emitting unit emits light towards the bubble tube from the upper or lower side thereof. A light-receiving element converts the light transmitted by the bubble tube into an electric signal. An operating unit calculates an angle of inclination based on the electric signal. The light-receiving element includes a light-receiving unit for position detection within a movable range of a bubble shadow and a light-receiving unit for reference outside the movable range.

Abstract: A verticality detecting apparatus for plumbing columns has a measuring section to be mounted on a lower end portion of an upper column, an upper target to be mounted on an upper end portion of the upper column and a lower target to be mounted on a lower end portion of a lower column joined to the lower end of the upper column. Inclinations of the measuring section about two orthogonal horizontal axes are adjustable and can be locked at adjusted inclinations. The measuring section consists of a sight telescope with a right angle prism opposed to its objective while placing an edge of the right angle on its optical axis perpendicular thereto, and an inclination sensor for detecting inclinations of the telescope-prism assembly about the two orthogonal horizontal axes.

Abstract: An auto-refractometer according to this invention comprises a light beam source for producing a measuring ray wherein beams from a pair of invisible infrared ray emission diodes are alternately flickered, and real images of the beams are converged on respective sides of ridges at the output side of a V-shape coincidence prism at positions close to the ray axis thereby reducing the horizontal distance between the beams. A measuring optical system includes a transmitting collimater which projects said measuring ray passing through a vertical slit to permit focusing of a slit image on the retina. A receiving collimator collects beams reflected from the cornea and the retina, and by a semi-transparent mirror, and directs them via a reflection mirror to an interference bar which interferes with the beam from the cornea. A split prism divides the beam received from the retina, and a pair of elements photo-electrically convert the divided beam into electrical outputs.

Abstract: An automatic digital indicating lens meter is provided with an optical system having a light beam source and a target which reciprocally moves within a certain range along the optical axis, the target having several circular luminous points. An image pickup system including a lens to be inspected, such as a mono-focal point spherical lens or a bi-focal non-spherical point lens, is fixed on the optical axis approximately mating with the luminous centers of a light beam source collimator and a light beam receiving collimator. A photo electric converter is located at the focal plane of the receiving collimator; on an extension of said optical axis. An electric circuit analyses by scanning lines, the images detected by said electric light converter as time series signals and counts the position when the time band width of the brightness signal becomes minimum in the course of movement of the target.