Abstract: Focusing optics placed behind the zooms optics of a zoom arrangement are focused by computing the necessary focusing movement in response to the output of a focal length detector and an object distance detector. Comparison is made to the actual position of the focusing optics.

Abstract: Disclosed is a method and an apparatus for detecting the leading edge of a sheet which is on the way to the scanning-and-reading station of an image read-out system. Detection is performed by exposing, just ahead of the scanning-and-reading station, the traveling sheet to the same scanning beam of light as used at the scanning-and-reading station, and by detecting the sudden change in the amount of reflection on arrival of the sheet at the station due to the difference between the reflection coefficients of the sheet and the underlying conveyer belt. Preferably, the scanning for detecting the leading edge of the sheet is at a higher frequency and smaller amplitude than the scanning for reading an image on the sheet.

Abstract: A small amplitude, low frequency, signal is added to the focus servo signal controlling the position of the objective lens of an optical disc storage system after focus acquisition has been achieved, so as to produce a slight defocusing effect of the light spot on the disc. The resulting variations in the read back signal is utilized by a synchronous detection circuit scheme to extract magnitude and polarity information of the focus offset present. That information is fed back to the focus servo signal to null out the focus offset, thereby assuring continual accurate focusing of the laser beam even under conditions of changes in the mechanical alignment of the optics of the storage system and/or the d.c. stability of the electronics of the storage system.

Abstract: The invention relates to a process and device for detecting foreign bodies in a liquid, wherein the image of the apparent surface of the liquid in rotation in the immobilized recipients is formed, by reflection, diffraction, refraction or attenuation of the light coming from a source, on a matrix of reception and read cells. In the matrix each cell is perfectly delimited and its position is identified by numerization. A series of images is produced, of which a certain number are taken as reference and memorized. Each image is digitized and those images following the last memorized image is compared therewith cell by cell by a subtractor.The results of such a subtraction are compared with a threshold and results overstepping the threshold involve delivering a signal to a processor which controls a sort device arranged to eliminate undesirable units.

Abstract: The blue light response of solid state photosensitive devices such as silicon based charge-coupled devices (CCDs), charged-injection devices, photovoltaic devices and the like is enhanced by applying to the surface thereof a thin layer which includes a first, or donor, dye which absorbs efficiently in the blue region of the spectrum and a second, or acceptor, dye which absorbs efficiently in the green region of the spectrum, there being substantial overlap between the emission spectrum of the donor and the absorption spectrum of the acceptor. The relative concentrations of the dyes are controlled such that the donor dye transfers energy nonradiatively to the acceptor dye which is caused to fluoresce thereby emitting light in the region where the device has substantial photoresponse.

Abstract: A detector for checking the symmetry of a helicopter rotor while it is rotating has a scanner (11) which scans vertically a field of view (15) and the view is interrupted by a vertical strip on the blade tip (16). A slot (18) in the strip gives a characteristic signal as at (L.sub.2). The position of the signal (L.sub.2) in a scanning cycle gives an indication of the height of the blade tip and also the circumferential spacing between blades.

Abstract: A solid state image sensing device comprises a photosensitive semiconductor element having a plurality of photocells on a surface thereof. A protective layer is disposed on the photosensitive semiconductor element, and an inorganic layer is disposed on the protective layer. A plurality of color filter layers each comprising a coloring agent having a color absorption characteristic are mixed into a portion of the inorganic layer in locations overlying the photocell, and a surface protective coating is disposed on a surface of the color filter layers.

Abstract: A probe is fixed to a vertically displaceable rack. Under the probe is a reference plate freely exposed to snowfall. The probe is periodically lowered toward the reference plate and stopped when it encounters either the plate or a layer of snow which has fallen on the plate. With the aid of a light barrier and a perforated disk, electrical signals dependent upon the distance travelled by the probe are generated and transmitted to an evaluating device. This device calculates, on the basis of the signals received, the difference between the aforementioned distance travelled and the distance from the reference plate to the probe in its uppermost position. This difference corresponds to the thickness of the deposit of snow on the plate. For subsequent measurements, a new reference value corresponding to the surface of the snow already lying on the plate can be used for the calculation. Hence there is no need for clearing the plate of snow after each alarm signal.

Abstract: The system includes a primary scanner which produces a scanning optical beam, and a photoresponsive error sensor which measures over the scan path the successive differences between the actual position of the scanning beam and the desired position of the scanning beam and produces error signals. The secondary scanner is connected to the error sensor for response to the error signals to dynamically correct the position of the scanning beam during the course of the scan. The primary scanner provides a main optical scanning beam and an auxiliary optical scanning beam traversing substantially the same optical path. The error sensor includes a graticule mask having a substantially uniform optical density along the desired scan path and a graded optical density transverse to the desired scan path of the auxiliary scanning beam.

Abstract: A pulse encoder having a circuit for diagnosing abnormalities such as the breaking of wire in LEDs or lowering of a power supply voltage, the pulse encoder comprising LEDs, a rotary lattice plate, a stationary lattice plate, light-receiving elements, and a driving unit for driving the electric signals from the light-receiving elements, the driving unit having a control terminal for controlling the output signal of the driving unit, wherein the anode of one of the LEDs connected to the ground is connected to the control terminal so that when the potential of the control terminal is lowered to a level lower than a predetermined value an alarm signal is output from the driving unit.

Abstract: A device for focusing a laser on a recording medium by wavelength modulation is disclosed wherein the device includes a radiation source for providing a radiation beam of controllable frequency, a hologram intercepting the radiation beam for focusing the radiation beam as a function of its frequency, and a control system coupled to the radiation source for controlling the frequency of the radiation beam so as to focus the beam on a desired plane. The control system includes a sensor for detecting the focus of the radiation beam on a desired plane, and means for controlling the frequency of the radiation beam from the radiation source responsive to the detected focus.

Abstract: An automatic focusing apparatus for optical instruments, in particular for reflected light microscopes, wherein a measuring point is produced on the surface of an object by an eccentric measuring beam formed by blocking a portion of the path of a full beam. The measuring point is imaged onto a photoelectric device by reflecting the measuring beam along the blocked out path. When the object plane wanders from the focal plane, the photoelectric device actuates a control device which returns the object plane to the focal plane. The apparatus comprises a source of light to produce a, preferably pulsed, laser light for the full measuring beam, an optical structural element for geometrically blocking one-half of the full measuring beam to produce the eccentric measuring beam and simultaneously for geometrically blocking the reflected measuring beam from the path of the full measuring beam.

Abstract: A method is provided for observing, preferably through the medium of an optoelectronic pick-up, the carrier to be checked which is illuminated by a light beam having an angle of incidence of at least 45.degree. through a rotary disc comprising alternately transparent and opaque sectors spaced from one another by a distance at least substantially equal to the distance measured between the lines of the copperplated printing formed on the carrier. The carrier image is formed in the plane of a detector by means of an optical system. If the carrier has a copperplate printing formed thereon, a moire effect is observed. If the pick-up extends over several transparent sectors of the disc this moire effect is converted electrically into a very pronounced periodic variation of the current delivered by the pick-up, at the sector passage frequency.

Abstract: An apparatus and method for detecting focus condition of an imaging optical system is disclosed.

Abstract: Timing pulses generated by an incremental optical encoder disc may be nonuniformly spaced due to eccentricity in the disc mounting and inaccuracies in the pulse generating marks. An apparatus and method are disclosed wherein pulse width measurements are made during one revolution of the disc, and from these measurements data relating to pulse delay information are computed and stored in a memory. During operation the leading edge of each encoder pulse is delayed by a period of time related to the stored delay information corresponding to that specific pulse.

Abstract: A sensing apparatus wherein a photoelectronic transducer and a light-emitting diode are adjacent to one end face of a bundle of fiber optics. The other end face of the bundle is located in the housing of an actuator wherein a reciprocable plunger can move a light absorbing or light reflecting element into and from the path of light issuing from the bundle. The position of such element influences the amount of light which is reflected back into the conductor to ensure that the signal which is generated by the transducer is indicative of the amount of reflected light. The transducer can transmit signals to a signal receiving device which, in turn, can influence the intensity of light issuing from the diode in dependency upon whether or not the device receives a signal from the transducer. The actuator can be installed in an area which is not explosion-proof or in an area which is exposed to pronounced electrical noise.

Abstract: A bistable circuit having a monolithic device with first and second optically isolated stages is disclosed. Each stage has a light emitting diode and a corresponding detector. Subsurface light from each diode provides optical feedback through the device to its corresponding detector.

Abstract: An array of light emitting diodes are fabricated in the substrate of a monolithic device. Each diode, when forward biased, produces output light which is emitted from the device and subsurface light which is transmitted through the substrate. A single detector is fabricated in the substrate and detects subsurface light from any forward biased light emitting diode of such array. In response to such subsurface light, the detector produces a signal which is representative of the intensity of output light emitted from the device by such forward biased light emitting diode.

Abstract: Apparatus for adjusting the position of an edge between two surface porti of a moving belt with different spectral reflectivities where required in connection with work or treatment needed along the edge of one of the two surface portions while the belt is moving. It is a pre-requisite condition that the mutually adjacent surfaces of the belt are sufficiently significantly optically detectable which is impaired, for example, in the presence of surface contamination by dirt and the like. In order to obtain a significant signal in such circumstances, the edge region is illuminated and an imaging or focussing lens associated with a beam splitter is arranged in the focus beam. Following the beam splitter the two part-beams pass through one filter each to impinge on in each case a photodiode receiver, each filter blocking passage in that wavelength range in which the other filter is transmissive.

Abstract: A position control device includes a generally rectangular, two-part housing having orthogonal walls, two of which have openings formed therein. A shaft is rotatably mounted in the housing on bearings which are respectively received in recesses in support blocks on the housing bottom. One end of the shaft projects outwardly through one of the openings and may have a knob secured thereto outside the housing. One-part and two-part shafts are disclosed. A control wheel is mounted coaxially on the shaft and projects through the other opening for manual rotation by a user. The support blocks cooperate with retainers on the housing cover to accommodate slight movement of the bearings in directions perpendicular to the plane of the control wheel opening, the shaft being resiliently biased toward that opening.