Abstract: An amplifier circuit has a voltage-amplifying stage, an output stage including a push-pull circuit comprising at least one complementary pair of output transistors, and a drive stage for driving the output transistors of the output stage in response to the output of the voltage-amplifying stage. The drive stage includes a subtraction unit and a signal-converting unit. The subtraction unit subtracts the output voltage of the voltage-amplifying stage, which is based on the first pole-potential of a power supply, from the reference voltage output by a reference voltage-generating unit also included in the drive stage. The subtraction unit outputs a voltage corresponding to the difference between the reference voltage and the output voltage of the voltage-amplifying stage, and supplies this voltage to the signal-converting unit. The signal-converting unit shifts the level of the input voltage, thereby producing a voltage signal based on the second pole-potential of the power supply.

Abstract: A method of making a single-mode evanescent-wave coupler having reduced wavelength dependence includes the steps of (a) providing first and second single-mode optical fibers having substantially identical propagation constants; (b) heating the first optical fiber along a first longitudinal segment thereof while stretching the first optical fiber to reduce the diameter of the first longitudinal segment, the reduced diameter being substantially uniform along the first longitudinal segment; (c) maintaining the first and second optical fibers in parallel juxtaposition with one another along a portion of the first longitudinal segment; and (d) fusing together the portions of the first and second optical fibers maintained in parallel juxtaposition to form a coupling region.

Abstract: Apparatus and method for detecting and modifying discontinuities on the ocular surface of a patient's contact lens by alternately observing the reflected image of one or more parallel opaque bands superimposed on an illuminated translucent background and modifying the ocular surface until the detected malformations are removed and the ocular surface conforms to the conjugate profile of the patient's corneal surface.

Abstract: A tracking loop having an enhanced ability to acquire a carrier signal and to remain locked on the carrier signal when the carrier frequency changes. The loop includes a nonlinear amplitude filter between the phase detector and the loop filter. The nonlinear amplitude filter receives the error signal e produced by the phase detector, and produces a modified error signal N for input to the loop filter. The nonlinear amplitude filter is designed such that N is an odd function of e, such that the derivative of N with respect to e is a constant k for comparatively small values of e, and such that the magnitude of N is greater than the product of k times the magnitude of e for relatively large values of e.

Abstract: An audio amplifier has a collapsible power supply coupled to an audio amplifier circuit to drive voltage rails of the power supply in an inverse relationship to the power consumed by the amplifier circuit. A variable gain input stage includes a linear potentiometer gain control followed by a gain stage and buffer to drive separate bass and treble controls, summed before appearing at the input of an integrated circuit amplifier. The main voltage amplification is provided by an integrated circuit, supplied with power by common base circuits to isolate the integrated circuit from power supply induced distortion. Staggered output stages are coupled to the output of the amplifier, the earlier stages having a longer duty cycle and light duty factor, while the later stages having a shorter duty cycle and heavier duty factor. A voltage doubler sensing power drawn by amplifier to modify voltage rails available at the output of the amplifier circuit.

Abstract: A device and process for programmatically generated and controlled in-circuit pin tests and gross functionality tests of operational amplifiers. The tests provide basic functionality verification of amplifier functions independent of other circuitry on the printed circuit board of which the operational amplifier is a component.

Abstract: A switched capacitor filter includes an amplifier in a feedback or feed-forward path thereof. The amplifier (A5, C6, S7,) has a gain dependent on the ratio of stray capacitances to the capacitors used in the filter so as to compensate for errors in filter characteristics which said stray capacitances would otherwise introduce.

Abstract: A jig for maintaining a work piece in a predetermined position relative to a cutting tool is comprised of first and second relatively flat members having respective first and second major surfaces for being positioned in facing relationship. Each body member has a pair of parallel elongated racks of substantially equal lengths, with a plurality of teeth spaced at predetermined intervals along respective major axes of each rack. The racks on the first body member are positioned substantially in registration with the corresponding racks on the second body member so that the teeth of the facing racks are meshed together to inhibit the first and second body members from being moved relative to one another along the major axis of the jig. The position of the first body member relative to the second body member is adjustable along the major axis of the jig in predetermined increments corresponding to the width of the interval between successive teeth so that the effective length of the jig is adjusted accordingly.

Abstract: The invention relates to a circuit arrangement for a low-frequency amplifier having volume control, particularly in car radios, for noise reduction when the volume control means (10) is set at minimum. The noise reduction is achieved in that the signal path following the last amplifier stage (23) incorporates an electrically controlled switch (26) by means of which the signal path can be opened when the volume control means (10) is set at minimum.

Abstract: A discharge ionization detector has a detector body with first and second chambers and an interconnecting aperture passageway. A glow discharge emission in the first chamber is directed through the aperture to cause ionization of column effluent species in the second chamber. A polarizing electrode creates an electric field to cause acceleration of ionized species toward a collector electrode coupled to an electrometer. The detector body is of an electrically-conductive material and is coupled to ground potential to reduce entry of glow discharge-produced electrons into the second chamber.

Abstract: When there is a loss of tracking in a signal tracking system, such as a phase-lock loop, some components of the system, such as high gain amplifiers, will tend to have their outputs driven to the rail. When the output of an amplifier used to drive a voltage controlled oscillator in a phase-lock loop is driven to the rail, not only is its gain reduced to a very low value but additionally this rail voltage will interfere with the signal reacquisition process of the system. The present invention detects when system conditions are such that the amplifier could change to a low gain condition, and provides feedback around the high gain amplifier during those conditions to keep its output substantially centered until the system reestablishes a tracking mode.

Abstract: A device, usable with an object having a layer, for measuring the thickness of the layer, includes a system for irradiating the object with light while changing its wavelength, the irradiating system having a light-emitting portion disposed opposed to the surface of the object, a photodetecting unit for detecting the light from the object irradiated by the irradiating system, the photodetecting unit having a light-receiving portion disposed opposed to the object, a system for detecting the thickness of the layer of the object on the basis of the detection by the photo-detecting unit, and a setting mechanism for positioning the object, relative to the light-emitting portion and the light-receiving portion, at a distance that substantially corresponds to an extremum of the quantity of light which is to be received by the light-receiving portion and which is variable with the positional relation of the object with the light-emitting portion and the light-receiving portion.

Abstract: A method is provided for contamination and irradiation measurement and a universal sensor for implementing said process. The individual portable sensor of the invention includes an electret a first face of which is at least partially in contact with the fluid which it is desired to monitor and electrodes disposed opposite the second face. An electronic circuit measures the field variation of the electret in the zone opposite said electrodes. An aerolic circuit ensures a constant flow of fluid over the electret.

Abstract: A connector for interconnecting optical fiber cables or an optical fiber with an optical component, the cable or cables having an optical fiber encircled by a tension resistant member comprising a yarn. The connector has a hollow cylindrical body which slidably receives a lens mount with a lens thereon, the optical fiber is secured to the lens mount and the tension resistant member is secured to the body so that the cable can be pulled without applying damaging stress to the optical fiber. The lens mount is spring biassed into its normal position in which is couples optical signals to another cable or to an optical component.

Abstract: In a filter arrangement, a first junction capacitor is arranged between the inverting output and the non-inverting input of a fully balanced amplifier and a second junction capacitor is arranged between the non-inverting output and the inverting input. Additionally, a first resistor is arranged between a first input terminal and the non-inverting input and a second resistor is arranged between a second input terminal and the inverting input. A first current source is connected to the non-inverting input and a second current source is connected to the inverting input. The current sources produce the reverse voltages for the junction capacitors across the resistors to define the capacitance values of these capacitors.

Abstract: A series of equidistant measuring heads is arranged at a uniform distance above a surface to be measured. Each head includes a light source emitting light through a narrow exit opening, and two light sensors arranged adjacent the opposite narrow sides of each opening. The light input characteristic of respective sensors is such that light reflected from the measured surface section is detected with a sensitivity which is inversely proportional to the different intensity of illumination of central and marginal points of the measured section.

Abstract: An amplifier having at least a pair of gain levels for each of the AC and DC components of an input signal. The non-linearity in gain is achieved through the use of feedback which varies, in stepwise fashion, with input sigal magnitude.

Abstract: A splice joint is effected between single mode polarization maintaining (SMPM) fibers (31, 32) in a manner so as to maintain polarization of light transmitted through the splice. Mating ends (57, 58) of the respective fibers (31, 32) are aligned and joined with ultraviolet curing epoxy (61). After the ultraviolet curing epoxy (61) is cured, five-minute epoxy (63) is applied over the joint so as to effect mechanical rigidity of the joint. In one arrangement, the five-minute epoxy is reinforced with a sleeve (55).Advantages include the ability to simplify splicing of SMPM fibers, while maintaining polarization characteristics of the fibers.

Abstract: Amplifier circuitry includes a differential pair of transistors having commonly connected electrodes driven by a normally constant current supply transistor. Portions of the output signals developed by the differential transistors tend to vary with variations in the magnitude of a first power supply potential. A control circuit causes the magnitude of the normally constant current source to vary so that the other excursions of the output signal are substantially equal in magnitude to the first power supply potential to provide balanced signals across the load. A feedback circuit stabilizes the magnitude of the normally constant current supply transistors against variations in the magnitude of another power supply potential or in the constant current supply.

Abstract: A ring laser gyro having a cavity with at least one transducer-actuated mirror is controlled to conform to a preselected model of cavity operation. Control is accomplished by sampling cavity data, comparing the data to the model to generate an error signal, and controlling the mirror according to the error signal. In a preferred embodiment, at least two mirrors are dithered and the model defines an optimal amplitude of mirror dither at which theoretical lock-in error is zero. In another preferred embodiment, the sampled data corresponds to laser intensity within the cavity and the model defines an optimal intensity displaced from the maximum within an operating mode of the cavity. The model may define a plurality of operating modes of the cavity, ranked according to gyro performance for different values of a preselected environmental condition. The environmental condition is then sensed on an ongoing basis and used to select an optimal mode.