Optical information processing

Although the price is currently a few dollars per mg - the price won’t hold up!! What do we need with vast quantities of isotopes, he left us with his picture of a future advertisement for a new washing powder with the ‘miracle’ ingredient isotopic C13’!!! Hence, rather than isotope separation alone, he pointed out that laser chemistry has much more to offer, for example, in the detection and control of chemical reactions, such as the direct observation of radiationless reactions and organic rearrangement reactions in molecular beams, and in the generation of transient diffusion photocurrents in liquids without the application of an external electric field. Concurrent with the conference an exhibition of lasers, optics, and electro-optical systems was held in the lounges of the Congress Centre. This offered an excellent international survey of the present state of equipment relating to the conference subjects. All work and no play would make ‘Jack’ a dull boy - however the social programme and many attractions of

Amsterdam left one with insufficient time to do everything. The tourist and cultural sides in all of us were accomodated by a boat trip through the canals, from the Congress Centre to the Rijskmuseum, where a reception offered by the Netherlands Ministry of Education and Science and the Board of Town Mayor and Alderman of the City of Amsterdam was held amidst the presence of old masters including Rembrandt and Hals. There were also opportunities for coach excursions of the local area and a Burgundic dinner party. In conclusion, a full and exciting conference, tinged perhaps with a little sadness that the reins controlling the direction of quantum electronics had switched from the hands of the physicist to those of the developer/engineer. However, this research field is barely past its adolescence age (17 years since the first conference in New York) and there will be much more exciting work to report when we meet again in Atlanta, USA for the next conference in two years time.

R.B. Dennis, B.S. Wherrett

BOOKS Beam and fibre optics J.A. Arnaud Academic Press, 1976, pp 447, $34.00 Fibre optics, beams, and integrated optics are currently under investigation in many laboratories by engineers, physicists, and mathematicians whose backgrounds vary from classical optics to microwave engineering. Each will have his own story to tell of the progress in this fast growing field. No single picture will be wholly satisfactory, for this subject is very much a meeting point for several disciplines. The present book is not the first to be written on this topicnor will it be the last. Whether it will endure to become one of those standard texts, which one always keeps to hand, remains to be seen. Certainly the subject matter is interesting and the author is an experienced worker in the field. The book originates from an ‘in house’ course taught by the author at Bell Telephone Laboratories during the years 1972-73. It is suggested that the book will be useful to ‘students, professors and research engineers in the field of electromagnetic communication’ and this seems a fair assessment. Some undergraduates will consult this book but on the whole it is more suitable for the use of research workers. An easy start is made in Chapter 1 with a descriptive treatment of beams and guided wave systems. Analogies are made with mechanical systems and this chapter is in fact very suitable for general reading. Thereafter the treatment is much more ‘compact’ and mathematical - covering gaussian beams, wave equations, geometrical optics, and various effects concerning slab and cylindrical waveguides. Free use is made of vector and matrix notation. This is not a book for those who wish to learn practical details of the subject. The object here is to present the basic theory of the subject within the framework of classical physics.

OPTICS AND LASER TECHNOLOGY.

DECEMBER

1976

Care must be taken when reading some sections not to read into the text that which is not there. For example, the section concerning group and energy velocity is short and could be misinterpreted by inexperienced readers seeking general ‘truths’. Apart from this the presentation is good with clear diagrams. Over 200 references are given, many of them being very recent, and these are listed at the end of each chapter. All reference authors are listed in the author index. It takes time to know a book but I think this one will appeal to many research workers in the field and to teachers of undergraduate and postgraduate courses.

M. G.F. Wilson Optical information

processing

Edited by Yu. E. Nesterikhin,

G. W. Stroke,

W, E. Kock

Plenum Press, 1976, pp 401, $39.00 This is a collection of the seventeen papers given at the First US-USSR Science Cooperation Seminar held at Washington in June 1975. The papers, all in English, were provided in camera-ready form for reproduction. The style of the language of the contributions from the USSR is generally adequate, though in a few places the meaning is obscure: these contributions make up about half the book. The order of printing the articles seems to be random. The work must be read as a whole to acquire coherence. A fascinating and complete picture emerges of the present state of the art of information processing and the technology of solid/liquid state devices, together with projections for future developments. There is much to interest the image analyst, and much essential reading for the forward-looking computer and communications engineer and the deviceorientated solid state physicist. A particular value of the

277

book arises because of its division into rather general articles on the one hand and into articles on specialist applications on the other. The first are written in an easy tutorial manner concentrating on principles and future projections rather than on mathematical details, while the reverse is true for some of the applications accounts. No less than six of the papers are from the Institute of Automation and Electrometry, Novosibirsk, Siberia. Most of the authors concentrate explicitly or implicitly on the comparative virtues of digital and optical processing and the linking of both in hybrid systems. Landauer provides perhaps the central theme by thoughtful comparisons of storage/memory by electron beam fabrication, magnetic surface recording, and lattice arrays of magnetic bubbles as against optically accessed memories, and of computer logic by radiative interaction as against semiconductor technology. He plays devil’s advocate in predicting the principal future role for the laser in the computer will concern input/output devices. This paper is complemented by those by Casasent and Kompanet on real-time optically addressed re-usable devices for modulators and page composers and by Lee’s contribution on non-linear real-time optical processing with reference to thresholding and logic operations. These papers include details of thermoplastic devices, the electron beam addressed oil target, electro-optic ceramics, liquid crystal devices etc., together with future projections for the development of device technology.

HELIUM-NEON LASERS

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Papers on holographic memories are due to Vander Lugt and the schools headed by Nesterikhin and Tverdokhleb. These deal with digital and analogue storage and retrieval, the development and properties of holographic mass memory, and specific problems in bulk data processing that may be solved by their use. Possibilities are considered for both fast access time read-write holographic memory and longer access read only storage. The link between the general articles and those on applications is made in the papers by Goodman, Curevich, and Thompson. Goodman provides a study of noise in coherent optical processing and concludes that the ‘advantages of parallelism in optical data processing are gained only at the price of decreased accuracy’. An information-theoretic approach to information loss in coherent optical processing is adopted by Gurevich. Thompson gives a view of the diffraction principles of coherent optical filtering, pattern recognition etc., with an excellent selection of examples useful for teaching purposes on image deblurring, band-pass filtering, amplitude and phase filtering etc. The only example of noncoherent processing is in one of the contributions from Novosibirsk on the analogue multiplication of three matrices with the order of 100 x 100 elements. On applications, there are papers on image deblurring by holographic filtering (Stroke and Halioua), the optical realization of the Hilbert and Foucault-Hilbert transforms (Arbuzov and Fedorov), from Koronkevitch’s group on the preparation of kinoform phase filters using thin films of vitreous chalcogenide and by Goldina and Troitsky on holography with asymmetric fringes. Finally, the field of application of information processing is widened by Kock to real-time processing by synthetic aperture radar and by Korpel to signal processing by means of acousto-optics. Korpel gives a particularly complete article and sounds a similar note to Landauer in respect of the competition of

278

Hughes advanced technology and volume production methods have produced helium-neon laser systems which are attractive to a wide spectrum of users. At one extreme, versatile and reliable sub-systems will satisfy the OEM market with large quantities of a proven product for use in such areas as information handling. construction, medical instrumentation and industrial process control. At the other, the small quantity customer gains equally from the experience and capability of Hughes and is able to select laser tubes, heads or systems from a wide range of output powers. This is one product group from the Company which offers a wide choice of optics, electronics, electro-optics and laser equipment from leading high technology manufacturers.

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OPTICS AND LASER TECHNOLOGY.

I

DECEMBER

1976

the rapidly developing semiconductor technology more complex schemes using acousto-optics.

with the

The book is characterized by the refreshing candour of a number of the contributions and an attempt to consider practical reality.

R.E. Burge

Quantum electronics

(Volume

1, Part A)

In the preface it is stated that the series ‘Quantum electronics’, of which this book is the first volume, should be suitable for advanced students, and new and advanced investigators of the subject. The authors of this volume do set a very high standard and it seems likely that the treatise will form an extremely useful reference collection for researchers in the field. There are very few errors in the text, which is extremely well presented, especially in view of some of the horrific formulae that appear. BS. Wherrett

Non-linear optics

Vision and acquisition

Edited by H. Rabin, C. L. Tang

I. Overington

Academic Press, 1976, pp xi + 472, g19.25

Pentech Press, 1976, pp 386,&14.00 It is now eleven years since the publication of the classic text ‘Non-linear optics’ written by N. Bloembergen. Although the articles in the present volume contain far more theoretical and experimental material, as far as the topics included and the style of presentation are concerned this book follows closely along the lines established by Professor Bloembergen. Appropriately he is the author of a short general introduction to the text. There are six other contributions, all of a review nature, by principal researchers In their respective fields. The book is divided into two parts the former of which is taken up primarily by Chapter 2 with an article by C. F Flytzanis on the theoretical approaches to the calculation of ‘Non-linear optical susceptibilities’. This contribution is not for the faint hearted; the author spells out, in great generality, detailed mathematical expressions for susceptibilities before turning to specific discussion of many individual models. This is the most detailed account of the subject known to the reviewer; there are about 350 references quoted. Chapter 3, ‘Measurements of non-linear susceptibilities’ by S.K. Kurtz, forms a pleasant complement to Chapter 2. Many of the pitfalls which lay in wait for the experimentalists are included. Considering the authoritative nature of Flytzanis’ article it seems a pity that in those following each author has found it necessary to repeat certain basic material and that a variety of notations are employed. Understandably this is true of most collections of reviews and it has the advantage that each chapter may be read independently and in a notation appropriate to the specific topic being discussed. However one feels that non-linear optics is now sufficiently well established that a coherent appraisal of the whole field may be made. Chapter 2 could have been the starting point for such an appraisal. For example, Chapters 5,6 and 7 deal respectively with the ‘Stimulated Mandelstam-Brillouin process’ (I.L. Fabelinski), ‘Spontaneous and stimulated parametric processes’ (C.L. Tang), and ‘The stimulated Raman process’ (Chen-Show Wang). All three are well written and useful articles, but nowhere is there any attempt to compare the theoretical methods used to describe various stimulated processes. Chapters 5,6, 7 form Part II of this text along with Chapter 4 on ‘Two-photon absorption spectroscopy’ by H. Mahr. A neat description of the theory and techniques of twophoton spectroscopy is followed by a survey of the diverse experimental results in solids, liquids, and gases.

OPTICS AND LASER TECHNOLOGY.

DECEMBER

1976

Although one would wish for the contrary, the dice are regrettably loaded against this book becoming a best-seller. The obscure publishers seem unfortunately unacquainted with a reader both competent enough to advise them on the value of a manuscript and to help the author out of his difficulties, and also one to correct proofs. The author thinks he understands the anatomy and physiology of the visual system, but it is a pity that he does not betray having mastered even their vocabulary. When it comes to a description of - presumably - his own experiments (Chapter 12) he surprises the reader with the contempt he appears to have for statistical analysis. As for the underlying philosophy of the book, namely its claim to deal with acquisition, why this is no more than a synonym for perception! If the author had bothered to consult a dictionary, even if he has forgotten his latin, he would have been probably much enlightened by the distinction between ‘cognition’ and ‘recognition’. However, the field is vast, and perhaps one should not dwell on what, to the author, are side-issues (even though they dominate the title of the book). But even his physics is wonky, as when he writes that ‘light reflected specularly is, to a greater or lesser [sic] extent, polarized’. The restriction is odd as even scattered light is polarized to a greater or smaller extent. As a member of ‘a national UK working party on image evaluation’, as he describes himself, he would be expected to define the modulation transfer function in terms somewhat sounder than the elusive ones of a response. The author and his colleagues, who are involved in guided weapons work, found it necessary to consult a large number of books, and he therefore thought there was room for this one. I hope that the United Kingdom’s effort in the control of guided weapons does not depend solely on their reading and understanding. I hope equally fervently that the book is already being translated into Russian and that the Supreme Soviet is passing a ukase making it compulsory reading for all their guided-weapon-smiths. The author’s judgement is absolutely correct in the following respect: there is room for a book on what may be called operational rather than laboratory perception. But it requires basic grounding in an understanding of adaptation, of sensory psychology, and above all of macrostatistics. The author has worked hard to provide a list of papers many of which are reliable, and which will be used when a competent attempt is made. For this we owe him a debt of thanks.

R.A. Wede

279