Abstract: An automatic angle compensator comprising a liquid sealing container 4 having transparent liquid to form a free liquid surface 1 sealed therein, light projecting systems 21 and 22 for projecting light at a given angle to the free liquid surface, and an optical system for guiding the light beam, which is reflected by the free liquid surface and irradiated from the liquid sealing container, whereby optical axis of the light beam reflected by the free liquid surface is aligned with optical axis of the optical system regardless of whether the free liquid surface is turned by 0.degree. or 90.degree., and automatic compensation can be achieved regardless of whether the system is positioned in horizontal or vertical directions.

Abstract: The present invention relates to a projector using laser light, and more particularly to a ring-shaped laser spot capable of forming a projected image having a ring-shaped projected image formed from a diffraction fringe, by interposing a diaphragm between a collimator lens and a target. The collimator lens transmits laser light emitted from a laser light source to the target to form a first projected image on the target. The diaphragm shapes the laser light transmitted through the collimator lens to form a ring-shaped second projected image as a diffraction fringe on the target.

Abstract: A tilt angle automatic compensator used for a device requiring verticality or horizontality is disclosed. The automatic compensator comprises a container 4 where a transparent liquid to form free liquid surface 1 is sealed, a light projection system for projecting light beam toward the free liquid surface at a predetermined angle so that it is totally reflected on the free liquid surface, and an optical system arranged at a predetermined position along optical path of the totally reflected light beam after passing through the container with sealed liquid and for equalizing change of reflection angle of optical axis corresponding to change of incident angle of optical axis in all directions. When the liquid container is tilted and incident angle of the light beam is relatively changed with respect to the free liquid surface, sensitivity varying according to the direction of change of reflection angle is optically compensated.

Abstract: An optical adapter for a light-wave rangefinder comprising a light emitting means for emitting a distance measuring light wave modulated by a predetermined modulation frequency, and a light receiving means for receiving a reflecting light wave reflecting from a target point to which the distance measuring light wave is directed, wherein a time delay between the distance measuring light wave and the reflecting light wave is utilized to determine the distance to the target point, the optical adapter comprising at least one photoconduction means for conducting distance measuring light wave and the reflecting light wave, and at least one single objective optical means for projecting the distance measuring light wave from the photoconduction means towards the target point, for condensing the reflecting light wave reflecting form the target point and for guiding the light wave to the photoconduction means.

Abstract: An inclination measuring apparatus having a prism and a container having a liquid sealed therein for providing a liquid surface perpendicular to the direction of gravity. A member constructed from thermal conductive material is position under the liquid surface to maintain the liquid surface level in the presence of ambient temperature changes.