Spectra-physics Gmbh

Other

Metcal, Inc.

John P Ekstrand

Raymond T Hebert

David L Wright

Philip S Carter, Jr

Kevin K Holsinger

Andrew Tomlinson

John P Goldsborough

Michael Hodges

A heater employs a ferromagnetic or like material heated by a varying magnetic field to heat the ferromagnetic material wherein the ferromagnetic material has a large cross-section comprised of many members of small cross-section insulated from one another and wherein for medical applications each member may be surrounded by a heat conductive electrically conductive coating.

Thermal induction heater

An improvement for a vacuum tube or a plasma tube comprises a cathode loop formed of a material suitable for induction heating. A support structure mounted inside the vacuum tube supports the cathode loop at a cathode position. A power supply mounted outside the vacuum tube includes an induction coil wrapped around the tube near the cathode position and generates an alternating electromagnetic field at the cathode position to induce heat in the cathode loop so that electrons are released into the vacuum tube. Finally, a DC bias is applied to the cathode through the support structure. The improved plasma tube with an induction heated cathode is particularly useful for an ion laser gain medium.

Induction heated cathode

A laser structure utilizes air cooling and RF induction excitation of a gaseous active medium. A means for exciting the active medium is provided including a switching power supply utilizing pulse width modulated switching to provide an RF energy output. The RF output is coupled to a tank circuit which comprises a capacitor, an inductor, and at least one coupling structure. A means for generating a magnetic field-along the axial length of the laser bore is provided and can comprise either permanent magnets or a DC source coupled to the coupling structure. The laser further includes means for dissipating heat from the laser bore by utilizing the coupling structures as convective cooling fins with forced air circulated thereabout.

Air cooled RF induction excited ion laser

A system for displaying information concerning position of a light beam comprises a detector generating a first signal indicating position of the beam along a first dimension, and a second signal indicating position of the beam along a second dimension. A crossed dot bar graph display is coupled to receive the first and second signals. The crossed dot bar graph display includes a first linear array of indicators (LEDs) for indicating position along the first dimension, and a second linear array of indicators for indicating position along the second dimension. The first and second linear arrays intersect at a center indicator. One dot is displayed in the first array showing deviation in the first dimension. One dot is displayed in the second display showing deviation in the second dimension. When both dimensions are aligned to the center indicator, only the center indicator is activated. The system can be expanded to any number of dimensions.

Crossed dot bar graph display for indication of position of a light

A DC control voltage being supplied to a pulse-width modulator in a switched resistor regulator control feedback loop is modified by addition of an AC offset voltage dither signal; the sum of the DC and AC voltages suffices to 'turn on' the pulse-width modulator in some, but not all, of the periods of the output pulse train of the pulse-width modulator. The output pulse train controls the switch in a switched resistor regulator to turn on for a minimum period of time in some, but not all, of the periods of switching the resistor into and out of electrical connection. Thus the switched resistor regulator obtains an average duty cycle which is substantially less than the duty cycle which could be obtained with the minimum pulse width. In an alternate embodiment, a switched resistor regulator is controlled by a plurality of switches (e.g. a pair of switches whose periods of switching the resistor into and out of electrical connection are phase offset) whose minimum 'turn on' voltage is staggered with respect to each other. Thus the minimum change in pulse width of the output pulse train of the pulse-width modulator is reduced, and the effective discontinuity in changes of pulse width output due to changes of the control voltage is reduced in slope.

Switched resistor regulator control when transfer function includes

A system for detecting position of a light beam propagating along a beam path utilizes a single variable gain preamplifier in a time shared mode for each of the outputs of a four quadrant position sensors. A detector mounted in the beam path and having a reference point, generates a plurality of signals indicating deviation from the reference in plural directions. A multiplexer is connected to the detector, and combines the plural signals into a time multiplexed output. A variable gain preamplifier normalizes the signals in the time multiplexed output to generate the normalized output. The normalized output is then supplied to a logic circuit for processing the normalized output to generate a position signal indicating the position of the light beam.

Beam position sensor with time shared normalizing circuit

Misalignment of a laser beam due to bending of a plasma tube for an internal resonator ion laser, or another structural element supporting beam guiding optics, is controlled by varying the distribution of heat flow out of the plasma tube or structural element to compensate for any misalignment in response to position of the laser beam. A detector is mounted along the optical path of the laser beam, and generates a position signal indicating drift of the laser beam from a preferred position. A cooling system, thermally connected to the structural material of the plasma tube or the structural element and connected to the detector, conducts heat out of the structural material in a controlled distribution in response to the position signal, so that misalignment of the optics due to thermal bending is minimized.

Angular optical cavity alignment adjustment utilizing variable

A switched resistor regulator is constructed whose duty cycle response is nonlinear with small changes in input control voltage. Specifically, the response of a pulse-width modulator is made to increase less than linearly with small changes in input control voltage. In a preferred embodiment, the pulse-width modulator is altered by comparing the input control voltage with a nonlinear reference signal, rather than the substantially linear reference signal which is used in prior art pulse-width modulators. Specifically, the nonlinear reference signal may be generated by a nonlinear reference voltage circuit, such as an RC charging circuit, or such as a D/A converter controlled by a clocked programmable microprocessor.

Feedback loop gain compensation for a switched resistor regulator

There is disclosed a diode snubber for the voltage transients generated in the parasitic inductance of a switched resistor when current therethrough is interrupted. Also disclosed is the use of such a diode snubber in: a series switched resistor regulator; a shunt switched resistor regulator; a hybrid switched resistor regulator and a passbank switched resistor regulator. Also disclosed is the use of a linear dissipative regulator in all these forms of switched resistor regulators to maximize the effiency of power delivery to the load.

Switched resistor regulator with diode-snubber for parasitic inductance

There is disclosed a diode snubber for the voltage transients generated in the parasitic inductance of a switched resistor when current therethrough is interrupted. Also disclosed is the use of such a diode snubber in: a series switched resistor regulator; a shunt switched resistor regulator; a hybrid switched resistor regulator and a passbank switched resistor regulator. Also disclosed is the use of a linear dissipative regulator in all these forms of switched resistor regulators to maximize the efficiency of power delivery to the load.

Shunt switched resistor regulator with diode snubber

A switched resistor regulator controls current flow through a resistor electrically connected to a load by varying the duty cycle of switching the resistor into electrical connection between of a power source and the load to regulate the power to the load. Both current and voltage regulation can be achieved. In a series switched configuration, current flow through a resistor in series with the load is controlled with current flow being maintained by a capacitor is parallel with the load when the resistor is switched off. In a shunt switched configuration current flow through a resistor in parallel with the load is controlled, with a capacitor parallel to the load also being used. In a hybrid configuration a shunt switched resistor is used while the current level to the load is changed by selecting one of several series resistors; a capacitor is also provided parallel to the load. In a switched resistor passbank configuration a series switched resistor is used with a capactitor connected in series with the load and parallel to the switched series resistor. A linear dissipative regulator is also connected between the supply and the load in parallel with the series resistance of the switched resistor regulator to reduce the minimum voltage drop to the load when the switching duty cycle reaches 100% for the series switched configurations or 0% for the shunt switched configurations.

Switched resistor regulator with linear dissipative regulator

A switched resistor regulator controls current flow through a resistor electrically connected to a load by varying the duty cycle of switching the resistor into electrical connection between of a power source and the load to regulate the power to the load. Both current and voltage regulation can be achieved. In a series switched configuration, current flow through a resistor in series with the load is controlled with current flow being maintained by a capacitor is parallel with the load when the resistor is switched off. In a shunt switched configuration current flow through a resistor in parallel with the load is controlled, with a capacitor parallel to the load also being used. In a hybrid configuration a shunt switched resistor is used while the current level to the load is changed by selecting one of several series resistors; a capacitor is also provided parallel to the load. In a switched resistor passbank configuration a series switched resistor is used with a capacitor connected in series with the load and parallel to the switched series resistor.

Switched resistor regulator

Method and apparatus for processing input binary encoded analog signals to precisely determine the time occurrence of positive-going and negative-going transitions. Such digital signals result, for example, when bar codes (e.g. Universal Product Codes) are optically scanned. Transitions are determined by detecting the zero crossings, at selected gating times, of the second derivative of the input signals. The selected gating times occur whenever the first derivatives of the input signals exceed a threshold level. The threshold level is determined in one embodiment by peak-to-peak detecting the input signals and adding this value to a rectified noise measurement signal.

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Palo Alto, CA, United States of America

John P Ekstrand