2270results about "Sagnac effect gyrometers" patented technology

A method of examining a sample, which includes: exposing a reference to a first set of electromagnetic radiation, to form a second set of electromagnetic radiation scattered from the reference; exposing a sample to a third set of electromagnetic radiation to form a fourth set of electromagnetic radiation scattered from the sample; and interfering the second set of electromagnetic radiation and the fourth set of electromagnetic radiation. The first set and the third set of electromagnetic radiation are generated from a source; at least a portion of the second set of electromagnetic radiation is of a frequency different from that of the first set of electromagnetic radiation; and at least a portion of the fourth set of electromagnetic radiation is of a frequency different from that of the third set of electromagnetic radiation.

An integrated optical circuit for use in a fibre optic gyroscope which senses rotation rates by determining a phase shift due to the Sagnac Effect between light beams travelling around an optical fibre sensing loop (4) in opposite directions, the circuit being provided on a silicon-on-insulator chip comprising a layer of silicon separated from a substrate by an insulating layer, the circuit comprising: rib waveguides (11) formed in the silicon layer for receiving light from a light source (2) and transmitting light to a light detector (3), fibre optic connectors (9) in the form of grooves etched in the silicon layer for receiving the respective ends of the optical fibre sensing loop (4); rib waveguides (11) formed in the silicon layer for transmitting light to and from said fibre optic connectors (9) so as to direct light beams in opposite directions around the sensing loop (4) and receive light beams returning therefrom, phase determining means and (13,17,31) integrated in silicon layer for determining a phase shift between the light beams returning from the sensing loop (4).

A temperature compensation method for denoising a fiber-optic gyroscope on the basis of time series analysis comprises four steps of: step 1, designing an experimental scheme, performing fixed point low and high temperature testing experiment on the fiber-optic gyroscope, and utilizing acquisition software for data acquisition; step 2, performing time series analysis on the zero offset data of the gyroscope, and establishing the mathematical model of the random error of the fiber-optic gyroscope; step 3, adopting a kalman filtering algorithm to filter random noise in the zero offset data of the fiber-optic gyroscope; and step 4, utilizing the data which is de-noised by the kalman filtering to identify the model structure of the temperature shift error of the fiber-optic gyroscope, and calculating the parameters of the identified model. The method establishes the multinomial model of the static temperature shift error of the fiber-optic gyroscope through time series analysis, kalman filtering denoising treatment and identification of the temperature shift error model structure and parameters. The method completely meets the real-time compensation requirement on the project, and has a better practicable value and a wide application prospect in the technical field of aerospace navigation.

Methods and apparatus are provided for determining the rotational rate of an optical gyro. An optical gyro comprises at least one substrate, a multi-frequency light source (MFLS) mounted on the substrate, and a resonator coupled to the MFLS. The MFLS is configured to produce a first light beam having a first frequency and a second light beam having a second frequency and phase locked with the first light beam. The resonator comprises an optical fiber coil having a hollow core. The resonator is configured to circulate a portion of each of the first and second light beams through the hollow core. The portion of the first light beam propagates in a first counter-propagating direction, and the portion of the second light beam propagates in a second counter-propagating direction. A measured difference between the first and second frequencies indicates a frequency shift proportional to the rotation rate of the optical gyro.

The invention relates to an integral structure of a triaxial optical fiber gyro inertia measuring unit, which comprises a mounting skeleton, three fiber optic gyro scopes, three accelerometers, a light source, a circuit board and a vibration damper. The mounting skeleton adopts a hollow hexahedron frame structure, each group of mounting holes are symmetrically arranged, and mounting lug bosses are arranged on the positioning end surface of the mounting holes. Three fiber optic gyro scopes form mutual space and are orthogonally arranged on the outer surface of the mounting skeleton, the light source and the circuit board are respectively arranged on the outer surface of the mounting skeleton which is corresponding to the three fiber optic gyro scopes, the three accelerometers form the mutual space and are orthogonally arranged on the inner surface of the mounting skeleton which is corresponding to the three fiber optic gyro scopes and near the geometric center of the mounting skeleton, and the vibration damper is arranged on the outer surface of the mounting skeleton. The measuring unit has the advantages that the quality is light; the degree of deviation between the mass center of an inertia measuring unit and the geometric mounting center is very small; the dynamic testing precision is high; the temperature field distribution of the inertia measuring unit is beneficial for the temperature compensation and control of each component, and the like.

An apparatus for analyzing, identifying or imaging an target including an integrated dual laser module coupled to a pair of photoconductive switches to produce cw signals in the range of frequencies from 100 GHz to over 2 THz focused on and transmitted through or reflected from the target; and a detector for acquiring spectral information from signals received from the target and using a multi-spectral homodyne process to generate an electrical signal representative of some characteristics of the target with resolution less than 250 MHz. The photoconductive switches are activated by laser beams from the dual laser module. The lasers in the module are tuned to different frequencies and a phase shifter in the path of one beam allows the beams to have an adjustable phase difference.

A system and method is provided which suppresses relative intensity noise in a fiber optic gyroscope by taking advantage of the frequency response of erbium fiber. In operation, the gain provided by the erbium fiber is added to the gain of the other components in the feedback loop to provide for stable loop performance up to about 250 kHz. The frequency response of the erbium fiber of about 3 kHz also provides a 6 db per octave roll-off, which, when used in a negative feedback control loop for controlling the current flowing to the gyroscope light source, allows for a relative intensity noise control loop with a bandwidth much greater than 3 kHz; this may be used in high performance gyroscope applications.

A method is provided for sensing an environmental effect upon a sensing element and includes exposing the sensing element into the environmental effect, producing a light signal in the sensing element, modulating the light signal with a modulation signal, and determining a path length of the light signal as a function of the modulation signal. A fiber optic sensor is provided that includes a light source producing a light, a sensing element optically coupled to the light source such that the light propagates through the sensing element, a detector optically coupled to the sensing element. The detector detects light intensity propagating in the sensing element. An electronics processor receives the detector output and produces a modulation signal for the light. The processor further produces an output signal indicative of the environmental effect as a function of the modulation signal.

The INERTIAL SENSOR TRACKING SYSTEM is an overall system installation consisting of wireless body pack transmitters, broadband telemetry transceivers, computer and monitoring equipment, and emergency power generation for tracking personnel in an underground mine environment. The system is designed to function with normal primary power and on battery operation in the event of an emergency. In the past inertial sensors have been large spinning mass gyroscopes and large mass-based accelerometers. These inertial sensors have required high voltage three phase electrical supplies. The “wearable” body pack must be battery operated and the sensors must be small and lightweight. Micro-Electro-Mechanical (MEM) sensors fulfill both the requirements of low weight and low power consumption. The accuracy of the MEM sensor has been developed sufficiently to incorporate, with de-noising algorithms, an accurate position-sensing device. The proliferation of broadband TCP/IP protocol based RF systems provides a standardized medium of transmission, which will work in an underground environment.

The invention discloses a dual-polarization interferometric fiber-optic gyro which belongs to the field of communication technology. The fiber-optic gyro comprises a light source, two linear polarized light generating circuits, two signal detection light paths, a polarized beam splitter/combiner, a polarization-maintaining coupler, a phase modulator and a polarization-maintaining fiber-optic ring; wherein the light source is connected with the input ends of the two linear polarized light generating circuits by optic fibers; two output ends of the two linear polarized light generating circuits are respectively connected with two ports at the same side of the polarized beam splitter/combiner by optic fibers through one signal detection light path; the port at the other side of the polarized beam splitter/combiner is connected with the polarization-maintaining fiber-optic ring through the polarization-maintaining coupler; and the phase modulator is connected between the polarization-maintaining fiber-optic ring and the polarization-maintaining coupler by optic fibers. Compared with the prior art, the fiber-optic utilizes the dual-polarized light to carry out the detection, thereby greatly improving the measuring precision and the measuring stability of the rotating angular velocity; meanwhile, the fiber-optic gyro has the advantages of simple structure, low cost, small volume, high sensitivity and wide application range simultaneously.

The invention discloses a fiber optic gyroscope temperature drift modeling method by optimizing a dynamic recurrent neural network through a genetic algorithm. The fiber optic gyroscope temperature drift modeling method by optimizing the dynamic recurrent neural network through the genetic algorithm comprises the following steps of (1) initializing network parameters, and establishing an improved Elman neural network model; (2) obtaining a training and testing sample; (3) training an improved Elman neural network, and optimizing model parameters through the genetic algorithm; (4) outputting forecasts of an fiber optic gyroscope, and compensating errors. The output of the fiber optic gyroscope processed through a denoising algorithm is trained by introducing the improved Elman neural model with self-feedback connection weight, constant iterative optimization is carried out on the model parameters through the genetic algorithm, and the optimal model is obtained according to the magnitude of the errors of the model under different parameters. According to the fiber optic gyroscope temperature drift modeling method by optimizing the dynamic recurrent neural network through the genetic algorithm, the complexity of the algorithm is taken into consideration, the accuracy of the fiber optic gyroscope temperature drift model is improved, the application of the fiber optic gyroscope temperature drift model in engineering is expanded, and certain practical significance is achieved.

An optical resonant modulator includes an optical ring resonator and an optical loop that is coupled to the optical ring resonator by two couplers. The optical ring resonator can have a hybrid design in which the ring resonator is formed on an electro-optically passive material and the optical loop is formed on an electro-optically active material. An amplification section can be inserted between the electro-optically passive and the electro-optically active sections. In analog applications, an optical resonator includes a Mach Zehnder interferometer section having an input and an output, with a feedback path coupling the output to the input. Applications of the optical modulator of the invention, and a method for modulating an optical signal also are disclosed.

The utility model discloses a method for testing the frequency properties of the photoelectric detector used for fiber optic gyroscopes. A signal generator produces sinusoidal signals and adds the signal to a light intensity modulator to carry out sinusoidal modulation on the optical power of the optical signal from the fiber source in order to produce an optical signal with sinusoidal components. The measured photodetector converts the modulated optical signal into an electrical signal and samples the electric signal by means of high-speed data acquisition card, then conducts narrowband filter and signal processing over the collected samples and calculates the corresponding frequency response. The frequency sequence pre-selected by a numerical control system changes the frequency at which the sine wave generator (NC) system sends out signals , tests a series of frequency point responses, which can be combined into an amplitude frequency response curve of the measured photodetector, and the curve is transmitted to the terminal computer for displaying and storage. By controlling all the test processes by numerical control system, the utility model has the advantages of automatic measurement, fast testing speed, high testing precision, and therefore is suitable for carefully weighing the photodetector frequency performance in the whole operating frequency range.

This invention discloses to a type of fiber gas lasers and fiber ring laser gyroscopes based on these fiber gas lasers. The fiber gas lasers comprise of excitation gases, optical resonator and excitation source, etc. The optical resonator is made by connecting two selected arms of a single mode fiber coupler to the two ends of hollow-core fiber to form a ring resonator. The hollow-core of the fiber is filled with excitation gases to act as gain medium. The fiber laser is simple to construct, lower cost, and has adjustable size and good amplification performance. The fiber ring laser gyroscopes based on this novel type of gas lasers can be applied on robotics, automobile navigation, etc.