A method and apparatus for detecting when a second object touches a digitizing panel while a first object is touching the digitizing panel is disclosed. The method includes the steps of generating a first composite signal when the first object touches the digitizing panel, the composite signal including a first touch-down signal component and an offset signal component, converting the first composite signal to a first digital value indicative of an amplitude of the first composite signal, filtering the first digital value to filter out the offset signal component and to output the first touch-down signal component, generating a second composite signal when the second object touches the digitizing panel, the second composite signal including a second touch-down signal component and the first composite signal, converting the second composite signal to a second digital value indicative of an amplitude of the second composite signal, and filtering the second digital value to filter out the first composite signal and to output the second touch-down signal component.

Method and apparatus for eliminating an offset signal in an electrostatic digitizing tablet

A resonator gyroscope comprises a reference laser generator to produce a reference light; a first slave light source to produce a first slave light locked to the reference light; a second slave light source to produce a second slave light locked to the reference light; a first optical filter cavity coupled to at least one of the first and second slave light sources to filter out high-frequency fluctuations in the respective first and second slave lights; a resonator coupled to said first and second light sources, the resonator having first and second counter-propagating directions and resonance tracking electronics coupled to the resonator to generate a first beat frequency, a second beat frequency, and a third beat frequency; wherein the rotational rate of the resonator gyroscope is a function of the first, second and third beat frequencies.

Light-phase-noise error reducer

A bi-directional pulsed ring laser that produces bi-directional light pulses that interact in such a way that they are phase conjugated. A nonlinear substance, such as a nonlinear crystal or fluid, that has an index of refraction that is dependent upon light intensity is located near a beam waist of the laser cavity to provide a self-lensing effect. Methods for reducing dead band beyond observable limits are also provided. The increased sensitivity of the bi-directional pulsed ring laser provides application in detecting magnetic susceptibility by detecting the change in phase between the arrival times of the bi-directional pulses at a modulator and the electrical signal of the modulator to determine the change in frequency of a coil that has magnetic susceptibility.

Bi-directional short pulse ring laser

One embodiment is directed towards a stabilized laser including a laser to produce light at a frequency and a resonator coupled to the laser such that the light from the laser circulates therethrough. The laser also includes Pound-Drever-Hall (PDH) feedback electronics configured to adjust the frequency of the light from the laser to reduce phase noise in response to light sensed at the reflection port of the resonator and transmission port feedback electronics configured to adjust the frequency of the light from the laser toward resonance of the resonator at the transmission port in response to the light sensed at the transmission port of the resonator, wherein the transmission port feedback electronics adjust the frequency at a rate at least ten times slower than the PDH feedback electronics.

Laser with transmission and reflection mode feedback control

Traditional compensation methods using temperature-related parameters have little effect when the ring laser gyroscope (RLG) bias changes rapidly. To solve this problem, a novel RLG bias temperature compensation method using readout signals is proposed in this paper. Combined with the least squares support vector machine (LS-SVM) algorithm, the novel method can improve the precision of the RLG bias. Experiments show that by utilizing the readout signals in the LS-SVM model, the RLG bias stability can be significantly raised compared to the original data. The novel method proposed in this paper is shown to be feasible, even when the RLG bias changes rapidly.

Temperature compensation method using readout signals of ring laser gyroscope

A ring laser gyroscope output optics detection system, including a rotational sensing system and cavity length control system for a multioscillator ring laser gyroscope, is disclosed herein that can operate with a simple upright symmetric optics mechanism, where the required signal separation is performed fully electronically. In a preferred embodiment, signal separation circuitry is provided which performs a 90° or π/2 radians phase shift to one of a set of heterodyned signals in order to extract the sagnac effect modulated Faraday frequency signals W A and W B . In order to deal with the inherent problems of crosstalk present in a Faraday biased system, alternative signal separation schemes suggest the use of a 45° or π/4 radians phase shift, as well as a 60° or π/3 radians phase shift. Complementary cavity length control schemes are presented in both fixed component and digitally controlled formats.

Ring laser gyroscope output optics detection system

A ring laser gyroscope output optics detection system, including a rotational sensing system and cavity length control system for a multioscillator ring laser gyroscope, is disclosed herein that can operate with a simple upright symmetric optics mechanism, where the reguired signal separation is performed fully electronically. In a preferred embodiment, signal separation circuitry is provided which performs a 90° or .pi./2 radians phase shift to one of a set of heterodyned signals in order to extract the Sagnac effect modulated Faraday frequency signals WA and WB. In order to deal with the inherent problems of crosstalk present in a Faraday biased system, alternative signal separation schemes suggest the use of a 45° or .pi./4 radians phase shift, as well as a 60° or .pi./3 radians phase shift. Complementary cavity length control schemes are presented in both fixed component and digitally controlled formats.

Robert Anthony Mitchell

Papers

Ring laser gyroscope output optics detection system

Output optics detection system