IEE Proceedings J (Optoelectronics)
Volume 132, Issue 5, October 1985
Volumes & issues:
Volume 132, Issue 5
October 1985
Editorial. Gyroscopes and monomode optical components
- Author(s): B. Culshaw
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, page: 249 –249
- DOI: 10.1049/ip-j.1985.0048
- Type: Article
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p.
249
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Requirements for gyroscopes for inertial navigation
- Author(s): J.D. Nuttall
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 250 –254
- DOI: 10.1049/ip-j.1985.0049
- Type: Article
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p.
250
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A simple explanation of inertial navigation is presented. The difference between ‘gimballed’ and ‘strapdown’ systems is explained. The performance requirements of a gyro for one nautical mile per hour aircraft IN system are derived.
Introduction to the noninertial quality rate gyroscope and its applications
- Author(s): B.T. Trayner
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 255 –258
- DOI: 10.1049/ip-j.1985.0050
- Type: Article
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255
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The historical origins of the differentiation between ‘inertial’ and ‘noninertial’ quality gyroscopes is explained and the use of ‘noninertial’ gyroscopes in vehicle systems is utlined. This encompasses use for vehicle stability, directional references and controls, sight line stabilisation and crude inertial navigation and guidance. This latter use emphasises why the terms above have been put in inverted commas. The applications require the vehicle positional attitude or the vehicle angular rate. Until recently, these have always been obtained by using position (or free) gyros and rate gyros, respectively, but the advent of high-speed computing has made it possible for rate gyroscopes to perform both tasks (but not, generally, vice versa). This has made it possible, in some cases, to replace two gyro systems by one system, with obvious savings, but the one system must combine the requisite qualities of the two it replaces. The qualities required of gyroscopes for the applications listed above are outlined and some typical parameters are quoted. The difference between 'iron' gyros and optical gyros in terms of their performance is emphasised, especially the noise and drift-rate characteristics. The importance of these characteristics with relation to the applications is discussed.
Serrodyne modulator in a fibre-optic gyroscope
- Author(s): C.J. Kay
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 259 –264
- DOI: 10.1049/ip-j.1985.0051
- Type: Article
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p.
259
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The paper describes the behaviour of a serrodyne modulator in a closed-loop fibre-optic gyroscope. The general form of the driving waveform is described. A closed-loop computer model is used to investigate the behaviour of such a modulator and its associated errors in a gyroscope. Experimental results are included which show agreement with the model. It is concluded that certain of these errors affect the scale factor of the gyro and its linearity. To reduce the errors to acceptable levels it is necessary to control peak phase and minimise flyback time. The value of flyback time must be known to provide compensation in a closed-loop gyro.
Feasibility of a heterodyne all-fibre optical gyroscope
- Author(s): I.P. Giles
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 265 –270
- DOI: 10.1049/ip-j.1985.0052
- Type: Article
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p.
265
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The paper discusses the feasibility of a novel heterodyne approach to the design of an all-fibre optical gyroscope. The IF is produced by source frequency modulation which also serves to reduce the effective source coherence. Such a technique offers distinct advantages in that the optical medium is completely passive, making it ideal for an all-fibre approach.
Two wide-dynamic-range signal-recovery schemes for the fibre-optic gyroscope
- Author(s): A.C. Lewin ; A.D. Kersey ; D.A. Jackson
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 271 –276
- DOI: 10.1049/ip-j.1985.0053
- Type: Article
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p.
271
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Two signal recovery schemes are proposed and demonstrated for the fibre-optic gyroscope which allow it to be operated at very high rotation rates. Both techniques transpose the Sagnac phase shift into that of a low-frequency electronic carrier signal. Initial results are presented for both recovery schemes.
All-fibre components using periodic coupling
- Author(s): R.C. Youngquist ; J.L. Brooks ; W.P. Risk ; G.S. Kino ; H.J. Shaw
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 277 –286
- DOI: 10.1049/ip-j.1985.0054
- Type: Article
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p.
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The paper presents a new class of all-fibre devices based upon periodic coupling principles. The two basic devices which are described are a birefringent fibre polarisation coupler and a two-mode fibre transverse mode coupler. Both devices consist of a ridged plate which is used to periodically stress a fibre with a periodicity equal to the beat length of the modes to be coupled. This periodic stress has been shown to result in almost complete power transfer for both the devices described. These ‘in-line couplers’ have been shown to have several applications, e.g. amplitude modulators, notch filters, polarisers, mixers etc. One of the most important results of the work in this area was the development of an all-fibre frequency shifter based upon the principles of periodic coupling. More work needs to be done in the design and engineering of these devices, and there is still room for new ideas and approaches.
A fibre optic serrodyne frequency translator based on a piezoelectrically-strained fibre phase shifter
- Author(s): J.P. Dakin ; C.A. Wade ; C. Haji-Michael
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 287 –290
- DOI: 10.1049/ip-j.1985.0055
- Type: Article
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p.
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An optical-fibre frequency shifter is described that is based upon the serrodyne technique and uses a simple piezoelectrically strained fibre as the phase shifting element. Acoustic damping and electronic feedback techniques for improving the response of the phase shifter are reported.
Locating and coupling fibres to integrated stripe waveguides
- Author(s): J.P.G. Bristow ; P.J.R. Laybourn ; A. McDonach ; A.C.G. Nutt
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 291 –296
- DOI: 10.1049/ip-j.1985.0056
- Type: Article
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p.
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A method for coupling fibres to Ti-diffused waveguides in LiNbO3 is described, by which ion-milled grooves in the LiNbO3 substrate are used to locate the fibres. The coupling loss is analysed, and fabrication parameters optimised to minimise insertion loss due to modal mismatch. A net insertion loss of −2.6 dB has been measured for the coupler.
Low-loss single-mode optical couplers
- Author(s): G. Georgiou and A.C. Boucouvalas
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 297 –302
- DOI: 10.1049/ip-j.1985.0057
- Type: Article
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p.
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The fabrication of very-low-loss single-mode optical-fibre couplers is described. The biconical fusion method has been used to investigate three types of single-mode fibre (i.e. depressed cladding, matched cladding and raised cladding), and losses of less than 0.05 dB have been obtained. Experimental evidence also shows that power transfer in the biconical fusion coupler cannot be supported by evanescent wave coupling between the cores of the fibres. The fabrication of polished-type couplers is also described for fixed and mechanically tunable output power splitting ratio couplers. Typically losses of less than 0.2 dB are possible.
Polarisation optics for monomode fibre sensors
- Author(s): A.J. Rogers
- Source: IEE Proceedings J (Optoelectronics), Volume 132, Issue 5, p. 303 –308
- DOI: 10.1049/ip-j.1985.0058
- Type: Article
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p.
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Polarimetric monomode optical-fibre techniques offer many advantages for sensing applications. Both line-integral and line-differential methods may be used. Special features of the polarisation behaviour of monomode fibres, which arise in a variety of sensors, are discussed, with particular reference to the separation of linear- and circular-birefringence components. Possible uses of nonlinear optical effects and the future requirements for specialised fibres are also discussed.
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