Abstract: A lattice interference-type displacement detection device including a scale having a penetration-type diffraction lattice formed on one side thereof, and an optical system positioned adjacent to the diffraction lattice and remote from the scale. The optical system includes a light source which emits a light beam along a light source optical path, a light beam divergence arrangement for branching the light beam into first and second divergence beams along first and second optical paths, respectively, and for causing the first and second divergence beams to be incident at a diffraction point on the diffraction lattice, a light beam mixing arrangement for generating first and second mixing light beams from a first group of diffraction light beams generated at the diffraction point, and an arrangement for converting the first and second mixing light beams into respective electrical signals. The scale also includes a light reflection surface remote from the optical system with respect to the diffraction lattice.

Abstract: A displacement sensor is disclosed, which permits a semiconductor laser to be used as a light source with less thermal effects thereof. A spindle 18 with a scale 32 mounted thereon is disposed in a housing 11 or displacement. In the housing are also provided a semiconductor laser 35 for projecting a laser beam onto the scale and a transducer 36 for converting light form the scale into an electric signal. A heat insulation arrangement 41 is provided between the semiconductor laser 35 and the scale 32 to prevent transmission of heat from the semiconductor laser 35 to the scale 32. A heat radiation arrangement for radiating heat from the semiconductor laser 35 to the outside of the housing 11 is mounted in the housing 11. Thus, thermal effects of the semiconductor laser 35 on the scale 32 are reduced, and thus the accuracy of measurement is improved.

Abstract: A grating-interference type displacement meter apparatus is disclosed wherein a convex lens or a concave mirror is disposed such that a focal point thereof is placed on a refraction plane or a diffraction plane of a diffraction grating, or wherein zeroth-order beams transmitted through the diffraction grating are reflected back in the same direction by a rectangular prism or a triangular prism for reentrance thereof onto the diffraction grating. Hereby, a plurality of optical beams produced by the diffraction grating are directed to propagate parallely to directions of propagation thereof defined in its design.

Abstract: A projecting apparatus wherein a work on a mount is illuminated by an illuminating device and an image of the shape of the work obtained through a light transmitted therethrough or reflected therefrom is formed on a screen by means of a magnifying-projecting device, characterized in that condensing lenses in the illuminating device and projecting lenses in the magnifying-projecting device are formed into zoom type lenses and a tuning device is provided for causing the illuminating scope of the condensing lenses in the illuminating device to correspond to the projecting magnification of the projecting lenses in the magnifying-projecting device.