Abstract: A method for measuring the optical parameters of a phase object, comprising recording a moiré pattern viewed through said phase object, said moiré pattern being formed by illuminating by means of a source of diffuse light, first and second gratings positioned in the space between said light source and said phase object, wherein the plane of said first grating is parallel to the plane of said second grating, and calculating the optical parameters of interest from said moiré pattern.

Abstract: A method for measuring the optical parameters of a phase object, comprising recording a moiré pattern viewed through said phase object, said moiré pattern being formed by illuminating by means of a source of diffuse light, first and second gratings positioned in the space between said light source and said phase object, wherein the plane of said first grating is parallel to the plane of said second grating, and calculating the optical parameters of interest from said moiré pattern.

Abstract: A multifocal lens having far and near vision zones is presented. The lens comprises a substrate in the form of a progressive addition lens and a modulation formed on a surface of the substrate. The substrate lens has far and near vision zones, selected in accordance with respective prescribed values of optical power required for the patient's eye at his distance and reading vision, and an intermediate transition region between the far and near vision zones. The modulation is of kind producing locally variable power addition such that the far and near vision zones of the multifocal lens are wider than the far and near vision zones of the substrate.

Abstract: A method and apparatus for measuring an optical property of an optical device, such as a convex or concave reflector surface, by locating a main converging lens having a focal length f.sub.1 in front of an optical measuring system capable of measuring collimation, and providing a carrier including an auxiliary converging lens for receiving a beam from the optical measuring system, and the optical device to be tested for reflecting back, via the auxiliary converging lens to the optical measuring system, the beam passed through the auxiliary converging lens from the optical measuring system. The carrier is located at a first position wherein the back focal plane of the auxiliary converging lens coincides with the front focal plane of the main converging lens, and the optical device to be tested is located on the carrier in the front focal plane of the auxiliary converging lens.

Abstract: A method and apparatus measuring the orientation of the body in space with respect to first, second and third orthogonal axes, by projecting a collimated beam of light onto a non-axially-symmetrical mirror carried by the body in space; directing the light beam reflected from the mirror through an instrument measuring beam deflections or curvatures; and measuring the beam deflections or curvatures about the three axes to determine the orientation of the body in space.

Abstract: A method of encoding an optical image comprises: converting the optical iamge to an image grid comprised of an image matrix of pixels each having at least two possible intensity values; providing a master grid comprised of a master matrix of pixels each having at least two possible intensity values; and transmitting, for each pixel location of the image matrix, a pixel intensity value representing the intensity value of the master matrix at the corresponding location, its complement, or a random intensity value, depending on the intensity value of the pixel in the image matrix at the corresponding location. Also described is an apparatus for carrying out the above encoding method.

Abstract: A level comprises a sealed casing which holds a liquid and has a flat bottom end. It also includes a light admissive top section, bearing a periodic grating of alternating transparent and opaque stripes. A float is in the liquid inside a compartment of the casing underneath the light admissive top section. The float is capable of changing its position inside the chamber so as to retain its position relative to the horizon when the chamber is filled, and a mirror on the top face of said float.

Abstract: A system for determining the index of refraction of a sample fluid in which light from a collimated light source is directed through a light pervious cell in which sample and reference fluids are held. The light from the collimated light source which is transmitted through the cell is deflected and is then directed through a pair of gratings to establish patterns. When the cell contains a reference fluid therein, first patterns are established, and second patterns are then established by replacing the reference fluid with the sample fluid. A measurement of the change between the first patterns and the second patterns is used for determining the index of refraction of the sample fluid.