Abstract: Differential amplifier stage, having circuit elements for setting the gain to zero, includes a first transistor and a second transistor, whose bases are respectively connected to the positive terminal of a voltage source by a first current generator and a second current generator and are also respectively connected to the emitters of a third and a fourth transistor via a first and a second diode. The emitters of the first and second transistors are both coupled to the negative terminal of the voltage source by means of a third current generator. The collectors of the third and fourth transistors are connected to the negative terminal of the voltage source. The base terminals of the third and fourth transistors respectivlely form first and second input terminals. On the other hand, the collector terminals of the first and second transistors form first and second output terminals.

Abstract: A focus detecting device arranged to detect the focusing condition of an objective lens by projecting a light flux from a light source onto an object through the objective lens and by sensing the light flux after it is reflected from the object. The focus detecting device is provided with sensors which produce information necessary for detecting the focal point of the objective lens by sensing the light of the light source reflected by the object. Degradation of the device's detection accuracy due to the eccentrically mounted objective lens is prevented when these sensors are symmetrically arranged relative to a plane containing the optical axis of the objective lens.

Abstract: A microwave amplifying apparatus includes a waveguide which is shorted at one end and supplied with a TM mode or a TE mode signal, a pickup probe mounted on the waveguide for converting the signal into a TEM mode signal, and microstrip lines and field effect transistors, or amplifier elements, for amplifying the TEM mode signal. A matching device is arranged on the shorted waveguide adjacent to an incidence side with respect to the pickup probe while an input terminal of the first-stage amplifier element is directly interconnected to an output terminal of the pickup probe. The device is, therefore, free from a signal loss otherwise developed between the pickup probe and the initial-stage amplifier element. The matching device consists of three conductive rods which are spaced a quarter-wavelength distance from each other, and three lock nuts for fixing the conductive rods.

Abstract: The amplifier comprises two like CMOS cascode circuits, each having a first and a second transistors with channels having a first plurality and a third and fourth transistors with channels having the opposite polarity, the drain of the first transistor being connected to the source of the second transistor, and the drain of the fourth transistor being connected to the source of the third transistor, the drains of the second and of the third transistors being connected to each other end composing one of the output terminals of the amplifier, the sources of the first transistors being connected to each other and to the drain of a fifth transistor with a channel having the first polarity, the source of which is fed by a first supply voltage, the sources of the fourth transistors of the two cascode circuits being fed by a second supply voltage.

Abstract: A precision differential amplifier having unity-gain buffer amplifier input stages on each side of the amplifier includes a primary feedback path between the collector and base of the inside buffer amplifier transistor which operates when the differential amplifier is operated within its linear operating range. Under an overdrive signal condition, the primary feedback path is opened and a secondary feedback is activated to control the collector and base of the inside buffer amplifier transistor, thus preventing saturation of the inside buffer amplifier transistor and cutoff of the outside transistor. The primary and secondary feedback paths consist of only semiconductor junctions, minimizing heat and loading effects, reducing power supply voltage requirements, and facilitating rapid overdrive recovery.

Abstract: Compensation for the effect of parasitic and stray impedance which is present at the inverting input of known current feedback wideband amplifiers is described. The compensation permits these amplifiers to operate at higher frequencies without degrading the gain flatness of the amplifier and also simplifies the circuitry required to maintain correct biasing.

Abstract: An operational amplifier includes a pair of differentially coupled PNP transistors driving a current mirror circuit. The base of the each of the transistors is coupled to the source of a JFET follower transistor each of which in turn has a gate coupled to one of the amplifier's inputs. First and second current sources are coupled to the source electrodes of each of the JFETs for the purpose of supplying a current thereto equal to that JFET's I.sub.DSS (its drain current when its gate and source are shorted).

Abstract: A semiconductor source of high power, spatially and temporally coherent light including means to prevent damage to the output face. A laser diode is disposed in optical contact with a power amplifier having a diverging active area which causes emitted light to be distributed over a large facet area.

Abstract: A vacuum tube amplifying apparatus provides predetermined varying dynamic response characteristics in order to enhance the playing characteristics of musical instruments, especially guitar.

Abstract: A single crystal of rare-earth-doped lanthanum beryllate, whose crystal orientation is suitably chosen, provides a laser medium whose index of refraction is substantially independent of temperature. A laser using such a crystal as the laser medium displays little or no thermal lensing, thus permitting high power operation without wavefront distortion.

Abstract: A high gate output stage for use with an amplifier which has high power supply rejection and which is stable at all frequencies is provided. An output current source and current sink are connected in series with a Miller capacitor coupled between an input terminal and output terminal of the output stage. Error signals coupled from a power supply source are allowed to sum at the output terminal with a compensating signal. Compensation circuitry is coupled to the input terminal for charge coupling a substantially equal but opposite amount of compensation charge related to the error signal from the power supply, thereby substantially cancelling power supply error signal coupling. Therefore, excellent power supply rejection and frequency stability are provided in a high gain output stage.

Abstract: An active low-pass filter especially suitable for inclusion in an integrated circuit and capable of operating at frequencies up to at least f.sub.T /.beta. of transistors within the filter. A bootstrap circuit is coupled to the emitter follower to reduce the capacitive effect of the emitter follower on the passed signal and to guarantee precision pass band gain match among the filters. A plurality of active filters may be connected across the signal path to provide a selection of bandwidths. A filter is switched into and out of the signal path by selectively enabling and disabling its current source.

Abstract: An optically pumped single mode laser, e.g., Nd:YAG crystal (20) with planoconcave mirrors is increased in efficiency by an order of magnitude to about 8% by optics (25, 27) for focusing the high power multimode output of laser diode arrays (21, 22) into the mode volume (20') of the laser medium (20). A plurality of these optically pumped single mode lasers (1-4) may be cascaded in a ring with dichroic mirrors (M.sub.1 -M.sub.4) at the corners for coupling in the laser diode arrays, each having its own means for spatially tailoring its beam to concentrate pump distribution inside the lasing mode volume of the medium. An InGaAlAs pump diode (30) with its wavelength the same as the lasing medium makes the ring unidirectional.

Abstract: For monitoring and controlling a laser beam, sample beams are monitored for three characteristics and the three monitor outputs are used to control the beam generation. The three characteristics monitored are the transverse distribution of energy within the beam (a) under far field conditions and (b) under near field conditions, and (c) total power within a known proportion of the beam. These are employed respectively to control (a) the position of a mirror which forms part of an optical cavity within the laser structure, (b) a beam pointing element, (c) a beam expander and (d) a power supply for the laser.

Abstract: A laser device in which an output of a switching circuit for DC/AC conversion is applied through a filter to discharge electrodes to generate an AC discharge therebetween to use it as a laser exciting source.

Abstract: In an apparatus for detecting a focusing state of an optical system, a laser beam generated from a laser unit is transmitted through a beam splitter to a convergent lens. The laser beam is converged by the convergent lens and projected toward the surface of an optical disk. The laser beam reflected from the disk surface is reflected by the beam splitter and projected through the aperture of a light shielding plate to a photodetector. The photodetector has first and second photo sensitive regions arranged concentrically, and when the convergent lens is in a focusing state, the levels of the first and second photo signals from the first and second photo sensitive regions are equal to one another, and the output signal from the differential amplifier is maintained at zero level. When the convergent lens is approaches the focusing state from the position sufficiently separated from the optical disk, a positive output signal is generated from the differential amplifier.

Abstract: An axial flow gas transport laser comprising an excitation tube through which gas flows along an axis of the tube, an inlet arrangement to feed gas towards the excitation tube and an outlet arrangement to discharge gas from the excitation tube. At least one of the inlet and outlet arrangements comprises a circumferential opening arrangement evenly distributed along the periphery of the excitation tube, substantially in a cross-section plane of the tube. A gas flow channel arrangement to the opening arrangement is directed at least substantially in the direction of the excitation tube axis and into the excitation tube at the opening arrangement for preventing wide-areal turbulances of the gas flowing in the excitation tube.

Abstract: In the optical imaging of two subjects located in different object planes, at least one objective should be capable of being displaced for focusing relative to the object planes, being displaceable absolutely in a shift-free manner and with a very high positioning reproducibility. To this end, a positioning drive, particularly a piezo positioning drive, effects movement at a housing section which is displaceable relative to the object planes and at least carries the objective, whereby the displaceable housing section must be connected to the remaining, stationarily situated housing via resilient connections which are formed by elastically deformable weak points of the housing. Apparatus fashioned in such a manner are employed particularly for automatic mask adjustment in the transfer of structures in the sub micrometer range on the semiconductor wafers by way of x-ray lithography.

Abstract: A gas oscillator consisting of a plurality of laser tubes with discharge electrodes arranged in a straight line so that the cathodes are next to each other, a gas drive, a heat exchanger to cool a laser gas and an exhaust device provided to expel the laser gas from the laser tubes and containing an injection device for non-ionized gas to separate and expel the ionized gas from the laser tubes so as to suppress electrical discharges between the cathodes of the laser oscillator.

Abstract: A transversally excited gas laser whose main discharge is initiated by a corona discharge triggered between auxiliary electrodes. The auxiliary electrodes are thereby respectively composed of a conductor which is enveloped by a jacket of dielectric which forms a single part. The jacket is provided with an incision between the two conductors parallel to the longitudinal axis, facing the main discharge path, and also is metallized at its outside. The incision projects UV light of the corona discharge into the region of the main discharge path and thus generates free electrons where they are most effective. The outside metallization increases the capacitance of the auxiliary electrode arrangement; and as a result, the corona discharge is intensified. The main discharge may possibly also be delayed such that the firing ensues in a more greatly ionized gas.