Showing papers on "Ring laser gyroscope published in 2005"

Fiber-optic gyroscope using an air-core photonic-bandgap fiber

Abstract: We show theoretically and experimentally that the use of an air-core photonic-bandgap fiber in a fiber-optic gyroscope can drastically reduce the noise and phase drift caused by Rayleigh backscattering as well as non-reciprocal and thermal effects.

Parametrically disciplined operation of a vibratory gyroscope

Abstract: Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

Single sensor ring laser gyroscope

Abstract: A ring laser gyroscope is described which includes a laser cavity configured to provide an optical laser path for a pair of counter-propagating laser beams, an optical sensor configured to receive a portion of the energy from the counter-propagating laser beams, and a unit configured to receive outputs from the optical sensor. The unit is configured to utilize the output to generate at least a residual path length control signal, a laser intensity monitor signal, and readout signals.

All-fiber single-mode fiber frequency-modulated continuous-wave Sagnac gyroscope.

Abstract: An all-fiber single-mode fiber unbalanced Sagnac gyroscope is described. The gyroscope is based on optical frequency-modulated continuous-wave interference and consists primarily of four Y-type single-mode fiber directional couplers and a single-mode fiber coil. The rotational velocity of the fiber coil is determined simultaneously by detection of the phase shift of the beat signal. The advantages and limitations of the gyroscope are discussed.

Differential birefringent fiber frequency-modulated continuous-wave sagnac gyroscope

Abstract: A differential birefringent fiber frequency-modulated continuous-wave Sagnac gyroscope is described. Due to the nature of the differential interferometer structure, the gyroscope can automatically eliminate the unexpected nonreciprocal phase drift (including the frequency drift of the light source) and make the resolution double.

A silicon micromachined gyroscope driven by the rotating carrier's angle velocity

Abstract: In this paper, a novel silicon micromachined gyroscope is introduced, which is driven by the rotating carrier's angular velocity. The principle of structure is analyzed .The mathematic module is also established and authors calculate the dynamics parameters of the gyroscope. The theories research and computer imitation have certificated that the principle of the gyroscope is correct.

Ring resonator in a Sagnac loop

Abstract: A study of a ring resonator in a Sagnac loop is presented. The results of a theoretical analysis based on Jones calculus are confirmed by experiments. Comparison of a ring resonator in a Sagnac loop with a ring only is performed, and the advantages of our scheme are pointed out. The scheme can be used to increase the measurement sensitivity to small birefringence and associated polarization mode dispersion and to decrease the threshold for Sagnac-loop-based nonlinear switching and laser mode locking.

The structure principle of silicon micromachined gyroscope driven by the rotating carrier

Abstract: The structural principle of a novel silicon micromachined gyroscope, driven by the rotating carrier's angular velocity, is presented in this paper. The authors construct the mathematical module of the micromachined gyroscope and the dynamics parameters of the micromachined gyroscope are also analyzed and calculated. The signal detecting circuit of the micromachined gyroscope is described. The micromachined gyroscope uses capacitive variation to sense angular velocity and such operation principle is demonstrated in the paper. Then, the signal processing circuit of the micromachined gyroscope is analyzed in detail. Finally, the finite element analysis tool — ANSYS software is used to analyze the oscillation module and frequency response of the micromachined gyroscope. The theoretical research and computer imitation have certified that the structural principle of the silicon micromachined gyroscope driven by rotating carrier's angular velocity is correct.

Scale-factor stabilised solid-state laser gyroscope

Abstract: The invention relates to solid-state laser gyroscopes for measuring rotational speeds or angular positions which are used, in particular for aircraft engineering. A gyroscope performances depend on the temperature stability of the scale factor thereof (S) which is 4A/μL, wherein L and A are the optical length and the area of the laser cavity, respectively and μ is a laser emission mean wavelength without the Sagnac effect. Conventionally, for gas lasers, each parameter of the scale factor is selected in such a way that it is temperature independent. The solid state lasers which are very different from the gas lasers are not treatable in the same manner. Said invention offers the laser cavity optical architecture based on the scale factor global conservation, wherein each parameter is temperature variable. An architecture which makes it possible to avoid optical mode hopes and several digital examples proving that inventive principles are applicable to standard materials are also disclosed.

Experimental study on a novel structure of fiber ring laser gyroscope

Abstract: Fiber Ring Laser Gyroscope (FRLG) is a novel resonant gyroscope which uses erbium-doped optical fiber as the gain medium and optical fiber as the ring resonant cavity. FRLG have advantages over conventional Interferential Fiber Optical Gyroscope (IFOG) with its simplicity in both the optical configuration and the electronic signal processing. The precision of FRLG depend on the linewidth of fiber ring laser output. So how to get narrower laser linewidth is key technology for FRLG. According to recently report, FRLG's laser linewidth reach 100 kHz, can not directly applicable to rotation sensing at present. A Stand-wave in the un-pumped erbium-doped fiber can induce self-written fiber grating, which have self-adaptable narrow band pass characteristics. Base on this, we propose a novel FRLG's structure. Two filter sections were used in this structure to make sure FRLG run in narrow linewidth and single mode. Fiber circulator, un-pumped erbium-doped optical fiber and Bragg grating (FBG) as the reflect mirror make up of the filter section. In this paper, we have optimized the parameters through a computing simulation. The theoretical and experimental study on FRLG has been finished. We get experimental results from them. FRLG which use this structure can get bidirectional laser output, the linewidth of laser can reach about tens kHz level and the power of laser output can reach 1dbm.

All-birefringent-fiber frequency-modulated continuous-wave Sagnac gyroscope

Abstract: An all-birefringent-fiber frequency-modulated continuous-wave (FMCW) Sagnac gyroscope is described. The rotation velocity of the gyroscope is determined by measuring the phase shift of the beat signal produced by the two counter-propagating laser beams in the birefringent fiber coil. A resolution of 0.02 deg/sec with a 100-m fiber coil has been observed.

The influence of noise on output of Ring Laser Gyroscope

Abstract: Although the effect of lock-in in Ring Laser Gyroscope (RLG) can be reduced sharply by introducing mechanical dither into the input of RLG, there is still much large RLG readout error, which is unacceptable for medium/high-precision inertial navigation, due to the appearance of dynamic lock-ins. Superimposing noise on periodic dither signal can reduce the influence of dynamic lock-ins further. The relationships of RLG output's deviation from mean and dispersion coefficient with noise intensity are analyzed with the inputs of both single noise and compound dither (periodic dither superimposed with noise), respectively. The results show that single noise is less practical than compound dither.

Cavity adjusting method for laser gyro and used light path and path length control mirror

Abstract: This invention discloses a laser gyroscope chamber adjusting method and its light path distance control lens The method is the following: to exert toothed wave voltage on four control units of the angle control elements; to whole scan loop light path in two-dimensional space, wherein, two control units in one group are of same frequency and reverse voltage; the maximum scanning voltage of the output light intensity is the chamber voltage of the best loop resonance light path The light path distance control lens comprises slotted vane , angle control element , matching loop and distance control element ii

Ring laser gyroscope combination sensor

Abstract: A ring laser gyroscope is described that includes a laser block having a laser cavity, a readout mirror adjacent a portion of the laser block, and a sensor. The laser block is configured to propagate both a clockwise and a counter-clockwise laser beam within the laser cavity. The readout mirror is adjacent a portion of the laser block and is configured to allow at least a portion of both the clockwise laser beam and the counter-clockwise laser beam to pass through. The readout mirror also causes at least a portion of the clockwise laser beam and at least a portion of the counter-clockwise laser beam to overlap. The sensor generates a readout signal from an overlapping portion of the laser beams and a laser intensity monitor signal from a non-overlapping portion of the laser beams.

Laser gyro light path control system

Abstract: This invention discloses a laser gyroscope light path time and frequency division system, wherein, the time division control system receives distance control component adjustable light path of control signal Z drive control lens generated by the light intensity high-frequency signal input light distance long signal measurement and control unit; the light intensity low frequency signal input light path bias signal measurement unit generates light path revise signal an and small-shake low frequency modulating signal S. The difference of the frequency division system lies in the following: the light intensity low frequency signal is input to each different frequency light path bias signal measurement and control unit to generate light path control signal which simultaneously input relative light path control part adjustable light path to the best.

Apparatus and method to facilitate laser gyroscope ionization

Abstract: An apparatus and method is provided for facilitating ionization of a gas medium of a laser gyroscope. The apparatus and method employ a solid state light emitting device as a start aid for the laser gyroscope. The solid state light emitting device has a wavelength at or below a threshold wavelength based on a work function of a cathode coating material to prompt ionization of a gas medium within the laser gyroscope.

Dither-stripping with the differential of dither rate signal for a ring laser gyroscope

Abstract: It is required for getting the ring laser gyro output purely related to the input rotation to eliminate the output of the modulated angular vibration from the ring laser signal. In this paper we discuss the dither stripping methods of compensating the ring laser signal by converting the rate signal of dither detector from voltage to frequency for a dither type ring laser gyro. We discuss the differential methods for getting rid of the offset of the V-F signal. And we develope the methods of compensating the phase differences between the ring laser signals and the V-F differential signals by using analog integrator and digital time delays. And also, we develope the gain calculation method by comparing the standard deviations of the ring laser signals with V-F differential signals. We implemented these methods and analyzed the effectiveness of these methods by comparing the dither trapping methods.

A robust quadrature decoding logic and its FPGA implementation for measurement of angular motion using a ring laser gyroscope

Abstract: A ring laser gyroscope outputs an interference pattern that rotates at a rate proportional to the rotation rate of the body on which the gyroscope is strapped. The standard measurement setup for similar such systems consists of a pair of photo-detectors followed by wave shapers that convert the'rotating interference pattern into a pair of pulse trains in quadrature. The phase relation between the two pulse trains indicates the direction of rotation, and counting anyone of the pulse trains over a period of time gives a measure of the incremental motion. Commercially available optical encoder assemblies using similar quadrature-output sensors implement a sequence of noise filtering, quadrature phase detection and counting to measure incremental motion. Such designs have certain limitations in so far as their applicability is concerned. This paper documents these limitations briefly and proposes a novel design and its FPGA implementation of an improved digital noise filter and a high-resolution quadrature ph...

New solutions for autonomous control and navigation

Abstract: The most precise navigation systems are commonly based on at least 3 laser gyros and 3 mechanical accelerometers, based on moving or tensioned elements. Laser gyro's "dead zone" guides to existence of additive subsystems, and mechanical accelerometer accumulate the "error of zero" and does not measure during the free fall of an object. Here is found that dead zone on laser gyro characteristics is a result of the precession of momentum of pulse of ring baghron. The necessity of precise laser gyro tuning in Alert city, Canada, is discussed. The method to minimize the precession and to avoid the dead zone on the output characteristics is proposed. Therewith new solutions for autonomous control and navigation are discussed. Here is proposed the autonomous unit of sensors of irregular movement without moving parts and without ring laser resonators, disposed motionless on the object to be measured, based on unique unified 6 mini modules of the autonomous resonatory devices (ARD's). Another new solution could be computer 3D-mouse without pad and with 3 independent outputs for each axis of irregular movement, or the gear of control, which could be arranged in the marker or pen. ARD theory, the experiments and testing are discussed.

Semiconductor laser and semiconductor laser gyro using same

Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor laser with a new structure suited for a semiconductor laser gyro, and to provide a semiconductor laser gyro capable of detecting rotations more accurately and simply than conventional gyros using the semiconductor laser by using the semiconductor laser. SOLUTION: A semiconductor laser is capable of emitting a first and second laser beams, and is provided with an active layer 24 and a first and second electrodes for injecting carriers to the active layer 24. The first laser beam 35 is a part of the emitted beam (L1) rounding on a polygonal path in the active layer 24. The second laser beam 36 is a part of the emitted beam (L2) rounding on the path in the reverse direction of the laser beam (L1). The active layer 24 includes at least one layer of semiconductor layer (A). The semiconductor layer (A) comprises a plurality of quantum dots comprising a first semiconductor, and a cover layer comprising a second semiconductor different from the first semiconductor and formed in such a manner as to cover the quantum dots. COPYRIGHT: (C)2006,JPO&NCIPI

Differential singlemode fibre frequency-modulated continuous-wave Sagnac gyroscope

Abstract: A differential singlemode fibre frequency-modulated continuous-wave Sagnac gyroscope is described. The gyroscope employs two Y-type fibre-optic directional couplers, two X-type fibre-optic directional couplers and a singlemode fibre coil to construct a time-division-multiplexed unbalanced fibre-optic Sagnac interferometer. The rotation velocity of the fibre coil is determined by measuring the phase difference between the two beat signals. Benefiting from the differential technique, this gyroscope can automatically eliminate the unexpected non-reciprocal phase drift (including the frequency drift of the light source) so that the accuracy and long-term stability can be significantly improved.

Oscillation Control for a Electro-Magnetic Vibratory Gyroscope

Abstract: This paper presents the design of the Automatic Gain Control (AGC) system for the drive axis of a electro-magnetic driven cylinder gyroscope. The simulation and experimental results show that the designed AGC excites the cylinder at its natural frequency and maintains a specified amplitude of oscillations, and also track the natural frequency shifts due to temperature variations. The sensing performance of the AGC driven gyroscope is shown to be greatly improved compared to that of the open-loop driven one.

Research on signal detection of re-entrant fiber optic gyroscope

Abstract: Re-entrant fiber optic gyroscope (Re-FOG), using a shorter Sangnac sensitive ring (SSR), makes the two counter-propagandizing lights re-enter the ring before they interference with each other when they reach the photo-detector. By this means, the Re-FOG gets the same detecting accuracy as the conventional interferometric fiber optic gyroscope (IFOG) that has several times length of the sensitive ring. In this paper, the principle of the Re-FOG is first reviewed. Then the output signal is analyzed. Finally a method of signal detection is presented.

Gyro employing semiconductor laser

Abstract: A semiconductor laser gyro comprising a semiconductor laser (10) emitting first and second laser lights and a photodetector which is located at such a position that interference fringes are formed by the first and second laser lights. The semiconductor laser (10) comprises an active layer, and first and second electrodes (13, 14) for injecting carriers into the active layer. The first laser light is a part of laser light (L1) circulating on a polygonal passage in the active layer, and the second laser light is a part of laser light (L2) circulating on that passage reversely to the first laser light (L1).

System, circuit and method for off-mode-peak operation of ring laser gyroscopes

Abstract: A system, circuit and method are disclosed for operating a Ring Laser Gyroscope (RLG) off-mode-peak to avoid exciting undesirable transverse modes. An alternate PLC operating point can be used to bias the optical path length of the RLG to an appropriate side of an ideal integer number of wavelengths, and thus avoid exciting the undesirable transverse modes. Although this alternate PLC operating point is not perfect with respect to establishing an integer number of wavelengths, this operation provides acceptable performance of the RLG's (in particular, short length path RLG's), and acceptable margin can be established relative to variations in the PLC set points involved.

Random Error Analysis of Ring Laser Gyro Using Allan Variance Method

Abstract: The Allan variance method is used in analyzing the static output signal of the Ring Laser Gyro(RLG) in iner- tial Measurement Unit(IMU).It can determine the character of RLG and identify the source of random error.The con- clusion afford the theory for improving the character of RLG.

Light path and path length control mirror for laser gyro

Abstract: This invention discloses a laser gyroscope light path and distance control lens, which is based on grasping card chamber length control lens and designs new slotted vane and angle control element. The slotted vane is a ring slot film lay structure of fused quartz glass or devitro-ceramics material, and its surface is coated with central column of the reflection film co-axis with outer ring, wherein, the central column is easily deflects and displaces under outer force. The angle control element is thin piezoelectricity ceramics and has a round hole, which let the grasping structure wire bar go through, wherein, the angle control element is stick to the slotted vane with co-axis. It exists different electrode voltages on two relative arms of angle control element to adjust reflection angle of the lens surface.

Testing and Modeling Laser Gyroscope Error Based on Neural Network

Abstract: The model of temperature compensation was setup by reverse error ba ck-propagation (BP) neural network of artificial neural network.The BP neural ne twork made temperature compensation by scale factor and random shift after train ed.

Coherence effects in ring laser gyros

Abstract: We show that the dynamics of photons in a ring laser gyro are adequately represented by the damped Rabi problem, and thus demonstrate a variety of photonic coherence phenomena analogous to those that occur in atoms. We discuss methods to circumvent the deleterious consequences and exploit the advantageous consequences of these effects. Specifically, we discuss the use of short pulses for the elimination of the gyro dead-band, the use of the dead-band locking frequency for the hypersensitive measurement of scattering and absorption, and the incorporation of fast and slow light media into the cavity for the enhancement of the gyro response.

Frequency-Biasing Technique of Laser Gyro

Abstract: Several main frequency-biasing techniques were introduced, and rate bias technique was compared with dither bias technique. The development of rate bias laser gyro, dither bias laser gyro and differential laser gyro both as home and abroad was given.