US Government as Represented by the Secretary of the Army

Other

Raymond L Filler

John R Vig

R Donald Peters

James M Frank

A quartz crystal resonator is excited in two different modes at the same time such that the mass change and the temperature change can be measured independently. In using such a quartz crystal the change in mass can be calculated accurately and in real time, independent of temperature effects.

Method for measuring mass change using a quartz crystal microbalance

The present invention provides for methods of increasing the frequency vs. temperature ('f vs. T') stability of Oven Controlled Crystal Oscillators to levels which are superior to atomic frequency standards and 100 to 10,000 times higher than that currently available from the best crystal oscillators. This method encompasses the steps of making an SC-cut quartz resonator with upper and lower turnover temperatures at or near the resonator's inflection temperature, inserting the resonator into a high-stability oscillator circuit, placing the circuit into a high-stability, high thermal gain oven and adjusting the oven temperature to a set-point at or near one of the resonator's turnover temperatures. A preferred embodiment of the method of the present invention is also disclosed which comprises forming an SC-cut quartz resonator with upper and lower turnover temperatures within 10 K of the resonator's inflection temperature, inserting the resonator into a dual-mode high-stability oscillator circuit which is placed in an oven having a thermal gain exceeding 5,000 and temperature fluctuations smaller than 50 mK and utilizing a thermometric beat frequency of said resonator to adjust the oven temperature to a set-point within 100 mK of the lower turnover temperature.

Method of making an oven controlled crystal oscillator the frequency of

The thermal hysteresis of quartz crystal resonators is measured by exciting two modes of a quartz crystal of interest with an external frequency source at a preselected temperature, calculating the difference frequency as between the modes, resetting to the original set temperature after temporarily altering the temperature, remeasuring the frequencies while maintaining the temperature and the difference frequency at the same respective values as the original values, and taking the mode frequency difference as representative of the thermal hysteresis of the crystal.

Method of measuring the thermal hysteresis of quartz crystal resonators

The acceleration sensitivity of an AT-cut quartz crystal plate resonator is educed by replacing the quartz crystal plate of the resonator with a quartz crystal plate having a flatter plate contour.

Acceleration sensitivity reduction method

A crystal resonator features two crystals mounted such that the acceleration sensitivity vector of one crystal is in an antiparallel relationship to the acceleration sensitivity vector of the other crystal. The composite resonator eliminates acceleration-induced frequency shifts for acceleration in all directions.

Acceleration-resistant crystal resonator

Disc shaped quartz crystal resonators of plano-convex, plano-plano, and bnvex configurations have the b-mode resistance raised relative to the c-mode resistance by the proper choice of mounting geometry, thus suppressing the undesired b-mode in precision oscillator circuits without the use of added circuitry.

SC-Cut quartz resonators with suppressed b-mode

A quartz resonator is made from a chemically polished quartz plate. The plate is placed in an enclosure fitted with at least three mounting clips to receive the plate. The plate is secured to the clips with an electrically conductive adhesive capable of withstanding operation at 350 degrees C. The assembly is cleaned and a metallic electrode deposited onto the plate until the desired frequency is reached. The enclosure is then hermetically sealed. The resulting resonator can consistently withstand extremely high shocks.

Method of making a quartz resonator

The apparent angle of cut of a quartz crystal resonator blank is shifted so as to give the quartz resonator a desired frequency versus temperature characteristic.

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Freehold, NJ, United States of America

Raymond L Filler