Abstract: A method and apparatus for producing a scintillation-immune adaptive optics reconstructor is disclosed. The present invention includes a wavefront sensor (70) which determines illumination slope and amplitude of a number of subapertures (75). The slope and amplitude information is coupled to a slope weighting function (90), which weights the slopes of each subaperture (75) according to the amplitude of illumination of each subaperture. The present invention determines the variation in light amplitude received by the subapertures (75) and determines a slope of the light amplitude variation. The signal gain of the imaging system is then adjusted depending on the slope of the light amplitude variation, thereby yielding a closed-loop system that compensates for amplitude disturbances caused by scintillations in the images received by the imaging system (10).

Abstract: A method for determining a resonant frequency of a mechanical device having a first mass and at least one second mass mechanically coupled to the first mass comprises the steps of: providing a control signal to a voltage-controlled oscillator (VCO) to control the frequency of an output thereof; translating a phase shifted output of the VCO into an oscillatory force which is applied to one of the first and second masses to cause the mechanical device to respond; measuring the response of the mechanical device and generating a response signal representative thereof in frequency and amplitude; generating an error signal proportional to the phase difference between a signal representative of the output of the VCO and the measured response signal; adjusting the control signal to cause the oscillatory force applied to the one mass to sweep within a calculated frequency range rendering the amplitude of the response signal to approach and exceed a calculated threshold value; and when the calculated threshold is excee

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.