Book Reviews

and oil films. Of course, the cost of these technologies varies from thous- ands to tens of thousands of pounds.

These chapters on technologies for colour displays are all well written, but because they form a small portion of the book the reader gets only a peripheral view of a subject that could benefit from a whole book devoted to it.

The final chapter of the last section, by Post, covers measurement tech- niques. This is a fine introduction to the practicalities of display characteri- zation and serves as a useful com- plement to Benzschawel's chapter on colorimetry.

As with many edited volumes, there is significant duplication of material. For example, the equations for AE* (page 61) and Silverstein and

Merrifield's small-field correction (page 67) in Benzschawel's chapter are duplicated in a slightly different form in Snyder and Trejo's chapter (page 102) and in Post's chapter (page 139). The different typesetting of the equations may well confuse the novice reader. The equations in Benzschawel's chapter defining CIELUV and CIELAB are duplicated in Snyder and Trejo's chapter, as is the equation for the power law in Walraven's chapter. The discussion of the definition of Yn for self-luminous displays in Benzschawel's chapter (pages 65-66) is duplicated in Post's chapter (page 140). There is also insufficient cross-referencing. For example, the discussion of brightness in Walraven's chapter (page 21) should point the reader towards Ware

and Cowen's brightness equation given in Post's chapter (page 151). The relationship between Lippert's equation in Benzschawel's chapter (page 69) and that in Post's chapter (page 158) is not made explicit.

Despite these criticisms, this is a fine volume. This book marshalls an impressive list of contributors from the world of colour displays and, with its wealth of equations and practical advice, it will make a useful handbook for the colour display designer.

David Travis BT Laboratories

Ipswich, UK

Surjit S Chadha University of Greenwich

UK

Liquid Crystals: Applications and Uses, Volume 2

B Bahadur Worm Scientific UK, London (1992) £52, 424 pp., ISBN 0 981 020403 5

This is presumably the last in a series of books edited by Birendra Bahadur on liquid crystal displays and devices, and other applications of liquid crystal materials. Each chapter of this book provides a review of a specific field, therefore it will be of use and interest to both established liquid crystal engineers and scientists and those just entering this very broad area of science and technology.

As in volumes 1 and 2, one chapter has been provided by the editor. In this instance, Bahadur has provided an extremely detailed description of dichroic liquid crystal displays, con- mined in 130 pages and representing one-third of the book. I know of no other single source of such detailed

and complete information on dichroic LCDs. This chapter is essential reading for those interested in this technology. The chapter on thermochromic liquid crystal devices, by Sage, is very read- able and well written, covering in detail the science and applications of this important class of materials. Again, this chapter is strongly recommended to all those working in this area of liquid crystal technology.

The chapter by Uchida and Seki on the surface alignment of liquid crystals covers this topic well. However, these authors have failed to make the point that very little is known about the mechanism of the surface alignment of liquid crystals, particularly the genera- tion and control of the pretilt angle on

rubbed polymer surfaces. The contri- bution by Kobayashi and Mochizuki, which has the non-specific title of 'Other Types of LCDs', covers seven less well known liquid crystal tech- nologies. Their brief description of the pi-cell, which is used as a fast optical shutter, particularly by Tektronix in their colour sequential systems, is a particularly useful description of an important, but rarely reported, technology.

Clark and Johnson, both of the University of Colorado, have provided a good description of the broad range of applications of liquid crystal devices, e.g. spatial light modulators, to the area of optical computing. A useful feature of this chapter is a description and comparison of the properties of commercially available devices that can be used in this area.

The final chapter by Finkelmann, Meier and Scheuermann, which covers the applications, structure and chemistry of both main chain and side chain liquid crystal polymers, was disappointing and does not do justice to this important area of liquid crystal

Displays Volume 15 Number 1 1994 51

Book Reviews

technology. This could be due to the very large amount of published information on this topic which in the past has led to books devoted solely to liquid crystal polymers.

Liquid crystal displays and devices provide a very wide range of exciting and relatively new technologies whose

importance will grow in future years. Yet, without exception, no author provided any indication of future directions or developments; perhaps reviewers feel they are constrained always to look back, but never for- ward. Nevertheless, this book, together with the two previous volumes, pro-

vides a timely and useful contribution to the literature on liquid crystals, which will be used by both scientists and engineers.

Alan Mosley GEC-Marconi Ltd

UK

52 Displays Volume 15 Number 1 1994