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Showing papers on "Ring laser gyroscope published in 1983"


Proceedings ArticleDOI
M. M. Tehrani1
19 Sep 1983
TL;DR: Cluster Sampling Technique is a powerful method for measuring the output stability of the ring laser gyro or any other oscillator in the time domain and the relationship between the cluster variance and the power spectral density of noise contained in the data is derived.
Abstract: Cluster Sampling Technique (CST) is a powerful method for measuring the output stability of the ring laser gyro or any other oscillator in the time domain. The relationship between the cluster variance and the power spectral density of noise contained in the data is derived. The former, being a directly measurable quantity, can provide information on the types and magnitudes of various noise terms. Analytical expressions for the cluster variance are derived for a number of prominent noise terms that are known to affect the gyro performance. The technique is applied to a long-term drift run of a Honeywell gyro and various noise terms are determined.

82 citations


Journal ArticleDOI
TL;DR: In this article, a fiber gyroscope was reported that uses polarization-holding fiber in the coil, the phase modulator, and the coupler, with a random-drift coefficient of 810−4deg/h within a factor of 2 of an experimentally determined quantum and thermal limit.
Abstract: A fiber gyroscope is reported that uses polarization-holding fiber in the coil, the phase modulator, and the coupler The random-drift coefficient, calculated from rms noise levels, was 810−4deg/h, within a factor of 2 of an experimentally determined quantum and thermal limit White-noise behavior was observed for integration time constants from 1 to 40 sec Device characteristics and performance are presented

61 citations


01 Oct 1983
TL;DR: An overview of inertial navigation is provided, followed by several sections detailing a specific, but different mechanization approach, and two gyroscopic approaches, presently in development are finally discussed.
Abstract: Inertial Navigation Systems have found universal application both militarily and commercially. They are self-contained, nonradiating, nonjammable, and sufficiently accurate to meet the requirements of users in a most satisfactory manner. An overview of inertial navigation is provided, followed by several sections detailing a specific, but different mechanization approach. A Ring Laser Gyro (RLG) based navigation system design is reviewed with special emphasis directed at requirements for navigation accuracy and alignment time. Along with discussions of the RLG unit, an introduction to a novel accelerometer approach, the Vibration Beam Accelerometer (VBA), is provided. A gimballed, self-contained High Accuracy Inertial Navigation System, denoted HAINS, represents one approach toward achieving navigation capability of 0.2 nmi / h and an rms velocity of 1.5 ft / s per axis while retaining the form and fit and affordability of standard inertial tactical flight navigators. The Stellar-Inertial Navigation section illustrates the bounding of position and verticality errors thus achieving exceptional accuracies. Two gyroscopic approaches, presently in development are finally discussed. The Fiber Optic Gyroscope (FOG) and Magnetic Resonance Gyroscopes (MRG's) are of interest for navigation because of their potential for low cost and excellent reliability.

30 citations


Patent
24 Mar 1983
TL;DR: In this paper, a fiber optic gyroscope comprising a Sagnac interferometer including a (3×3) optical directional coupler is driven with an essentially unpolarized broadband spatially coherent light beam supplied by a super-luminescent diode source.
Abstract: A fiber optic gyroscope comprising a Sagnac interferometer including a (3×3) optical directional coupler. The gyroscope is driven with an essentially unpolarized broadband spatially coherent light beam supplied by a super-luminescent diode source. A significant reduction in baseband noise occurs due to the use of the essentially unpolarized light beam.

27 citations


Patent
Irl W. Smith1
29 Jun 1983
TL;DR: In this article, a ring laser gyroscope system using a non-planar path and no-depolarizing Faraday bias means to achieve four-frequency differential operation is presented.
Abstract: A ring laser gyroscope system uses a non-planar path and no-depolarizing Faraday bias means to achieve four-frequency differential operation. The use of the non-planar path eliminates the crystal rotator normally used to provide reciprocal bias and therefore eliminates scattering surfaces and a major cause of thermal sensitivity. The non-depolarizing Faraday means, such as a thin glass slab having a component of magnetic field along the optic axis of the laser, is used to reduce the corresponding thermal sensitivity of the traditional Faraday bias element normally implemented by a crystal such as quartz. Eliminating these major sources of drift then allows higher-order sources of drift to be corrected. Zeeman splitting of the laser gain medium is used to provide an equal amount of dispersion to each of the two counter-travelling waves of each wave pair, thus eliminating small amounts of drift due to the different phase shifts produced in the propagating waves by the gain medium.

23 citations


Patent
James B. Matthews1
29 Apr 1983
TL;DR: In this paper, a four-frequency laser gyroscope system with a rugged and compact output structure for producing output signals representing the frequency differences between counter-circulating wave pairs circulating as two beams within the cavity is presented.
Abstract: A four frequency laser gyroscope system having a rugged and compact output structure for producing output signals representing the frequency differences between counter-circulating wave pairs circulating as two beams within the gyroscope cavity. A partially transmitting dielectric mirror forms both one of the cavity reflectors and the means for extracting a small portion of each beam. The two extracted beams are combined on a beam splitter. Both the transmitted and reflected beams from the output of the beam splitter, each containing waves of all four frequencies, are utilized. Each resultant beam is then polarization discriminated to extract the desired signal content. The entire structure is adapted for rigid mechanical coupling and may be constructed to have a small size.

18 citations


Patent
17 Mar 1983
TL;DR: In this article, a path length controller is provided for a three-axis, cube-shaped ring laser gyroscope assembly having three four-sided gyroscopes with six mirrors, including three movable mirrors and three fixed mirrors.
Abstract: A pathlength controller is provided for a three-axis, cube-shaped ring laser gyroscope assembly having three four-sided gyroscopes with six mirrors, including three movable mirrors and three fixed mirrors, wherein the controller connects between the three movable mirrors and the three fixed mirrors, and is adapted to change the pathlength of one gyroscope without changing the pathlengths of the other two gyroscopes.

17 citations


Patent
31 May 1983
TL;DR: In this paper, the rotor magnet of a gyroscope disposed in an associated guided missile system is disclosed, and a signal from the cage coil of the system is used to generate a constant amplitude drive signal for driving the precession coil.
Abstract: An apparatus comprising, inter alia, gyroscope feedback circuitry which aw scanning the rotor magnet of a gyroscope disposed in an associated guided missile system so as to increase the seeker field thereof is disclosed A signal from the cage coil of the gyroscope having an amplitude approximating a sine function of the angular position of the spin axis of the rotor magnet portion of the gyroscope with respect to the body axis of the associated guided missile is used to generate a constant amplitude drive signal for driving the precession coil of the gyroscope Scanning, so as to drive the rotor magnet in a predetermined scan pattern is accomplished by phase shifting the signal from the cage coil as a function of its amplitude and then driving the precession coil with the aforementioned constant amplitude drive signal which is phased-locked to the phase shifted or processed cage coil signal

16 citations


Patent
25 Aug 1983
TL;DR: In this paper, a ring laser gyroscope has a primary ring including a gas discharge tube enclosing an active lasing medium, and a secondary, passive ring 14 optically coupled to the primary ring by a partially transmissive mirror.
Abstract: A ring laser gyroscope has a primary ring 13 including a gas discharge tube 4 enclosing an active lasing medium. The gyroscope has additionally a secondary, passive ring 14 optically coupled to the primary ring 13 by a partially transmissive mirror 8. A mirror 15 of the secondary ring 14 is adjustable, under the control of a feedback loop 19, to vary the optical path length of the secondary ring 14 so that the latter resonates at one of the longitudinal modes of the primary ring 13, thereby enhancing this mode and concentrating the output power of the gyroscope in one frequency, while suppressing other longitudinal modes of the primary ring.

15 citations



Patent
26 Aug 1983
TL;DR: A ring laser gyroscope has noise reduction means which removes or compensates for errors which result when a bias or dither is imparted to the gyronscope in order to reduce or avoid lock-in this paper.
Abstract: A ring laser gyroscope has noise reduction means which removes or compensates for errors which result when a bias or dither is imparted to the gyroscope in order to reduce or avoid lock-in. In one embodiment the gyroscope has processing means (25) including two photodiodes (26,27) which are exposed to the fringe pattern of the gyroscope output beams and which, by the use of a Norton input operational amplifier (30) configured as an electronic integrator, produce a signal which is algebraically summed with the uncorrected gyroscope output signal to produce a corrected gyroscope output signal.

Patent
20 Apr 1983
TL;DR: In this paper, an improved ring laser rotational rate sensor includes a pair of lasing cavities, each of which is comprised of a non-planar arrangement of four cavity segments.
Abstract: An improved ring laser rotational rate sensor includes a pair of lasing cavities, each of which is comprised of a non-planar arrangement of four cavity segments. Common gain and biasing media are associated with closely-spaced segments of the two cavities. The non-planar cavity geometry supports only circularly optically polarized lasing modes thereby requiring no intracavity elements for optical biasing and eliminating the need for dithering of mirrors to control optical path length.

Patent
07 Nov 1983
TL;DR: In this paper, a ring laser gyroscope having apparatus for compensating a gyromagnetic output signal for optical power variations in accordannce with variations of a dihedral frequency is described.
Abstract: A ring laser gyroscope having apparatus for compensating a gyroscope output signal for optical power variations in accordannce with variations of a dihedral frequency. A scaler quantity is determined based on operational data and it is used to compensate the gyroscope output signal. Alternatively, a gyroscope output signal is compensated via a feedback network by adjusting the gain medium in the laser gyroscope in accordance with variations in the dihedral frequency.

Patent
08 Jun 1983
TL;DR: In this article, a ring laser gyroscope is affected by one or more retroreflective prisms or pairs of cofunctioning transparent wedges mounted in a dither compensation plane parallel to the plane of the laser light path.
Abstract: Dither compensation in a ring laser gyroscope is effectuated by one or more retroreflective prisms or by one or more pairs of cofunctioning transparent wedges mounted to the gyroscope casing in a dither compensation plane parallel to the plane of the laser light path in the gyroscope cavity. Prisms or beam splitters reflect at least one of two counter-rotating laser beams to the dither compensation plane from the plane of the cavity. An optical sensor comprising a photodiode for detecting and analyzing the interfering laser beams can be placed in the dither compensation plane or in the plane of the gyroscope cavity.

Patent
25 Feb 1983
TL;DR: In this article, a ring laser gyro is provided with a discriminant means (320) for providing a output signal (610) related to a selected weighted vectorial sum of the coupling of energy between counterpropogating waves traveling about a closed-loop path.
Abstract: An angular rate sensor, in particular, a ring laser gyro, is provided with a discriminant means (320) for providing a output signal (610) related to a selected weighted vectorial sum of the coupling of energy between counterpropogating waves traveling about a closed-loop path The discriminant means is utilized in a closed-loop control system (330) for minimizing the lock-in rate of the sensor and/or maintaining and selecting scale factor linearity (Figure 6)

Patent
14 Jan 1983
TL;DR: In this paper, a laser gyroscope output signal generator for increasing the resolution of the gyromagnetic signal was proposed, which includes a first output producing means for producing a plurality of output pulses for each gyro-scope produced output pulse when the gyro is rotated in a first direction for connection to a down count input of a counter.
Abstract: A laser gyroscope output signal generator for increasing the resolution of the gyroscope includes a first output producing means for producing a plurality of output pulses for each gyroscope produced output pulse when the gyroscope is rotated in a first direction for connection to a down count input of a counter. A second output producing means is also provided for producing a plurality of output pulses for each gyroscope produced output pulse when the gyroscope is rotated in an opposite direction for connection to an up count input of said counter.

Proceedings ArticleDOI
19 Sep 1983
TL;DR: In this paper, the bias as a function of net tilt out-of-plane, magnetic field and net mirror retardance is calculated and its importance as an error source in the planar square ring laser gyroscope is discussed.
Abstract: The square ring laser, unlike the triangular ring, can exhibit a bias due to the combined effect of slight nonplanar deformations (a reciprocal rotation effect) and an applied magnetic field (a nonreciprocal rotator). In this paper, the bias as a function of net tilt out-of-plane, magnetic field and net mirror retardance is calculated and its importance as an error source in the planar square ring laser gyroscope is discussed.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Journal ArticleDOI
TL;DR: An analytical method of matching the mode of an input laser to the lowest-order mode of a passive resonant ring laser gyro is described, as are the steps in determining the location and focal length of cylindrical mode matching lenses.
Abstract: An analytical method of matching the mode of an input laser to the lowest-order mode of a passive resonant ring laser gyro is described, as are the steps in determining the location and focal length of cylindrical mode matching lenses. Results were obtained with no mode matching, with a compromise spherical lens, with horizontal mode matching only, and with the proper cylindrical mode matching lenses. Compared with no mode matching, the latter case shows that the amplitude of the lowest-order mode is increased ∼2.5 times. In addition, the number and intensity of higher-order modes are reduced to near zero, and the relative intensity of the lowest-order mode to the higher-order mode increased from ∼5 to ∼60 times greater.

Patent
11 Jul 1983
TL;DR: In this paper, a path length controller for a ring laser gyro is presented, where the path length is dithered by dithering of one or more of the mirrors and the mirror or mirrors are controlled by a servo which is selectively biased in response to the servo signal to keep the mirror and mirrors in a position to support the largest amplitude of the principal mode of laser oscillation.
Abstract: A path length controller for a ring laser gyro wherein the path length is dithered by dithering of one or more of the mirrors and the mirror or mirrors are controlled by a servo which is selectively biased in response to the servo signal to keep the mirror or mirrors in a position to support the largest amplitude of the principal mode of laser oscillation


Patent
26 Aug 1983
TL;DR: In this paper, three photodiodes 1, 2 and 3 are spaced so as to expand to half a wavelength of an interference waveform produced in a ring laser gyroscope.
Abstract: Detection means comprise at least three photodiodes 1, 2 and 3 which are spaced so as to expand to half a wavelength of an interference waveform produced in a ring laser gyroscope. The three photodiodes 1, 2 and 3 produce respective currents A, B and C the magnitudes of which are detected to sense the magnitude and direction of the movement of the interference waveform. The currents A, B and C are fed to a current mirror configured as a Norton amplifier input state 4, the latter producing signals which are fed to logic circuitry for obtaining signals representative of the rate and direction of the movement of the interference waveform.

Patent
12 Apr 1983
TL;DR: In this article, the authors proposed to make it unnecessary to insert a Faraday element into the laser resonator by giving a bias for removing lock-in through utilization of application of the Faraday effect of the optical rotatory power substance in the resonator.
Abstract: PURPOSE:To make it unnecessary to insert a Faraday element into the laser resonator by giving a bias for removing lock-in through utilization of application of the Faraday effect of the optical rotatory power substance in the resonator. CONSTITUTION:In the 4-wavelength ring laser, a crystal is used for isolation of counterclocked circularly-polarized mode and clockwise circularly-polarized mode. A crystal has the Faraday effect in the same axial direction, and its Verdet's constant is 0.019min/cm.Oe. Therefore, it is possible to give the function of Faraday element by giving a field to a crystal. According to this structure, it is not required to insert the Faraday element into the laser resonator, and therefore a cause of giving adverse effect on the laser oscillation such as reflection absorption misalignment at the end surface of Faraday element can be eliminated. In the attached Figure, 1 is a Faraday element having optical rotatory power and 2 is a mirror, 3 is an electromagnet.

Patent
01 Jul 1983
TL;DR: In this paper, a ring laser gyro scale factor enhancement circuit is proposed, which is connected between at least one power supply voltage level and a reference potential for conditioning at least a first and second input signal from a ring-laser gyro assembly.
Abstract: A ring laser gyro scale factor enhancement circuit connected between at least one power supply voltage level and a reference potential for conditioning at least a first and second input signal from a ring laser gyro assembly, the first and second input signals being essentially sinusoidal and having a common first input signal frequency, the second input signal having a predetermined first phase relationship with the first input signal for a first ring laser gyro rotational sense and a second predetermined phase relationship with the first input signal for a second ring laser gyro rotational sense. The ring laser gyro scale factor enhancement circuit comprises at least one frequency multiplier circuit responsive to the first and second sinusoidal input signals at a first signal frequency for providing at least a first and second relatively sinusoidal output signal at a higher output signal frequency, the frequency of each first and second relatively sinusoidal output signal being a multiple of the integer two raised to a positive integer power times the common first input signal frequency of the first and second input signal; whereby, the ring laser gyro output signal scale factor is enhanced.

Proceedings ArticleDOI
04 Oct 1983
TL;DR: In this article, the surface quality of a ring laser gyro (RLG) is investigated. But the damage to this class of optics that results from typical processing and handling is not discussed.
Abstract: The surface quality of optics used in an extremely sensitive laser instrument, such as a Ring Laser Gyro (RLG), is critical. Experimental evidence is presented on the damage to this class of optics that results from typical processing and handling. Also presented is a possible solution to this problem.

Journal Article
TL;DR: In this article, two configurations of the passive resonant ring laser gyroscope were evaluated, and the first configuration detected cavity resonance by monitoring the beams transmitted through the cavity, while the second configuration detected resonance using the reflected beam increased sensitivity three-fold.
Abstract: : Two configurations of the passive resonant ring laser gyroscope were evaluated. The first configuration detected cavity resonance by monitoring the beams transmitted through the cavity. The second configuration detected resonance by monitoring the beams reflected from the cavity input mirrors. The resonant cavity of both configurations had a rated finesse of 9800, making the gyro much more sensitive than earlier versions. Additionally, much of the cavity noise that plagued earlier experiments was eliminated by mounting the cavity mirrors on a solid ceramic block, and evacuating the beam paths. Alignment data indicated that the signal strength in the reflected beam had six times the power of the signal in the transmitted beam. However, the bias on the reflected signal was seven times the signal strength. This bias intensity increased the shot noise in the detector circuit. Rotation was simulated in the gyro by shifting beam frequencies. The strength of the error signal was calibrate to angular rotation. A signal to noise ratio of one was then converted to a noise equivalent rotation. Using a 100 second integration time, the noise equivalent rotation of the first configuration was twelve milli-earthrate, and four milli-earthrate for the second configuration. The detection of resonance using the reflected beam increased sensitivity three-fold.


Patent
22 Sep 1983
TL;DR: In this article, a ring laser gyroscope is provided with a readout arrangement in which its two readout beams (5,6) are combined and the polarisation thereof modified such that a sngle combined beam (18) is provided having linear polarisation.
Abstract: A ring laser gyroscope is provided with a readout arrangement in which its two readout beams (5,6) are combined and the polarisation thereof modified such that a sngle combined beam (18) is provided having linear polarisation the plane of which rotates as a consequence of change of phase difference between the readout beams (5,6), and thereby corresponds to the rate of rotation of the ring laser gyroscope.

Proceedings ArticleDOI
M. M. Tehrani1
19 Sep 1983
TL;DR: In this article, a new optical device for measuring inertial rotation was proposed, which uses the non-reciprocal frequency shifts of the self-oscillations generated in a phase conjugate ring cavity under rotation.
Abstract: We propose a new optical device for measuring inertial rotation. The device uses the nonreciprocal frequency shifts of the self-oscillations generated in a phase conjugate ring cavity under rotation. We present the analysis of this concept and obtain the scale factor equation of such a gyro. The results of a preliminary experiment are also discussed.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Patent
21 Sep 1983
TL;DR: In this paper, a ring laser gyro includes a resonator structure having a dielectric cylindrical ring with highly polished surfaces, which is of such thickness and length as to support propagation only of selected modes of energy excitation by confining to within the ring wavelengths of light impinging the surfaces of the ring at other than the critical angle and allowing the selected mode of light to escape into the gain medium at critical angle.
Abstract: A ring laser gyro includes a resonator structure having a dielectric cylindrical ring with highly polished surfaces. The dielectric cylindrical ring is of such thickness and length as to support propagation only of selected modes of energy excitation by confining to within the ring wavelengths of light impinging the surfaces of the ring at other than the critical angle and allowing the selected mode of light to escape into the gain medium at the critical angle. A gain medium surrounds the dielectric cylinder, and reflectors for extracting counter rotating light heams generated by said gain structure and resonator are included adjacent said dielectric ring to intercept from opposite directions evenescent light waves supported by said dielectric ring.

Patent
15 Aug 1983
TL;DR: In this paper, a ring laser-gyroscope was constructed by drawing out laser beams through a Brewster window, reflecting the laser beams from a concave mirror and forming an annular photoelectric circuit.
Abstract: PURPOSE:To manufacture the ring laser-gyroscope easily by drawing out laser beams through a Brewster window, reflecting the laser beams from a concave mirror and forming an annular photoelectric circuit. CONSTITUTION:Laser beams 9 are extracted to the outside by a small damping factor or returned into a glass block 1 from the outside by forming the Brewster windows 7, 8 to the glass block 1. Laser beams 9 drawn out of the glass block 1 are reflected by the concave mirror 4, and returned into the glass block 1. The concave mirror 4 is set up to a L-shaped support base 10, and a position to laser beams 9 is fixed.