Abstract: The invention relates to a measuring window for a process refractometer. Process refractometers are commonly used in the industry for continuous measurement of the concentration of a solution. The wall of the refractometer facing the process solution is provided with a window which must satisfy the requirement that the passage of light rays satisfies certain criteria, that the sealing is reliable, that the fastening is firm and that the wall facing the process and the window form a planar surface. The transparent portion of the window according to the invention comprises a roof prism embedded in a V-shaped groove in the process wall. Each wall of the V-groove is provided with a sealing abutting against the prism, and the third side of the prism forms a continuous plane with the process wall.

Abstract: An alignment system and method is provided having an alignment target pattern formed on a semiconductor wafer, with means for scanning that target pattern to produce signals representing dimensions of individual features therein and distances between adjacent features, and with means for interrogating these signals to determine the relative position and distance of the scanned portion of the target pattern from a predetermined reference position. The target pattern includes one or more series of concentric figures, each figure having a particular dimension which differs from the particular dimension of each adjacent figure by a predetermined magnitude and being spaced from adjacent figures by predetermined distances. These predetermined distances and magnitude are detected from the scanning means signals and are used to determine the distance and direction of the scanning position from a reference position.

Abstract: The disclosure is directed to an apparatus and method for obtaining an improved moire fringe pattern image of an object. A beam of incoherent light is projected at the object. A grating is disposed in the path of the beam projected at the object, this grating being referred to as a projection grating. Means are provided for focusing the beam reflected from the object to obtain an image at an image plane. Another movable grating is disposed at the image plane. This movable grating is referred to as a reference grating. Means are provided for recording the image at the image plane, the recording means being, for example, a photographic or video camera. In accordance with an important feature of the invention, means are provided for moving the projection grating and the reference grating in synchronism. In a preferred embodiment, the projection and reference gratings are mounted in spaced relation in a movable member, and the synchronized motion of the gratings is implemented by moving the member.

Abstract: The distance between first and second grating-like structures such as a shadow mask and a faceplate of a color picture tube or the size of pattern elements of the second grating-like structure such as black stripes formed on the inner surface of the faceplate is optically measured. The shadow mask has a periodic pattern of apertures or slots and the faceplate has a periodic pattern of the black stripes. An optical system located between a light source and an assembly of the first and second grating-like structures applies parallel rays of light to the assembly and is arranged to vary an incident angle of the parallel rays to the assembly. A photodetector detects the quantity of light passed through the assembly to produce an electric signal whose amplitude periodically varies with variation in the incident angle of the parallel rays to the assembly.

Abstract: The invention relates to an apparatus for measuring the wave surface distortions introduced by a lens, comprising a source which emits coherent light of frequency .nu.o; means for creating a reference beam and a measuring beam; a Bragg cell receiving and transmitting said beams, excited by a radio-frequency wave of frequency f emitted by a generator, the reference beam transmitted having the frequency .nu.o and the measuring beam diffracted by the cell having a frequency .nu.o+f; means for transmitting the beams from the cell to the lens to be tested; detection means transforming the light signal from the lens into an electrical signal of frequency f and whereof the phase is characteristic of the wave surface distortions introduced by the lens; and means for measuring the phase displacement between the phase of the electrical signal from the detection means and the phase of an electrical signal corresponding to the radio-frequency waves.

Abstract: An optical position indicating apparatus having a light source, a detector for detecting the presence of light and producing an electrical output in response thereto, a reflecting structure for reflecting light from the light source across a target zone, and, a retroreflecting structure for reflecting the light incident thereupon along a path substantially coincident with the path of incidence of the light. The retroreflecting structure comprises a plurality of retroreflective assemblies, the reflecting structure and the plurality of retroreflective assemblies are substantially disposed about the target zone and a limiting structure limits the detector to a finite viewing range so that rotation of the detector effects scanning of the target zone.

Abstract: The geometry of rolling-mill rolls is monitored dynamically by projecting light between portions of the two rolls which are formed with circumferential grooves and the resulting light pattern is detected and compared with a pattern prior to start of the rolling operation.

Abstract: A method and an apparatus for detecting a flaw on threads of a male screw, which comprises: fully applying a light from a light source onto tops, roots and flanks of threads of a male screw while rotating the male screw around the axis thereof; continuously measuring, by means of a photoelectric converter, electric signal values corresponding to variations in brightness of the male screw in the axial direction thereof during one turn of the male screw around the axis thereof; moving-averaging the thus measured electric signal values corresponding to the variations in brightness of the male screw in the axial direction thereof; determining electric signal values corresponding to variations in brightness of the male screw in the circumferential direction thereof, on the basis of the thus moving-averaged electric signal values corresponding to the variations in brightness of the male screw in the axial direction thereof; obtaining a mean square value of the thus determined electric signal values corresponding to

Abstract: A method for detecting optically an F-number of an interchangeable imaging lens is disclosed. An image of an exit pupil of the imaging lens is projected onto an array of photoelectrically converting light receiving elements so as to measure a diameter of the image of the exit pupil of the imaging lens formed on the light receiving element array. The diameter of the exit pupil image is measured by counting the number of the light receiving elements whose photoelectrically converted outputs are larger than a predetermined threshold value and then the effective F-number of the imaging lens is detected in accordance with said counted number. Further, an image lateral shift amount detected by an image lateral shift detection system is corrected by the detected F-number and an accurate focus detection of the imaging lens can be performed.

Abstract: The invention is a multi-channel position detection system which utilizes several separate emitters and a single photodetector to, for example, align a multi-lead component manipulator with a predetermined location in a printed circuit board. An oscillator circuit generates a modulated signal for each emitter and a multiplier circuit develops an output signal based upon the oscillator output and the photodetector output. The photodetector provides an output responsive to the emitter signal as attenuated by the circuit board location relative to the emitter. When the lead hole of the circuit board is aligned with the emitter and photodetector minimum attenuation of the signal occurs.