In recent years, the field of optics has become extremely important because of its applications in many diverse areas. This is primarily due to the advent of the laser which has helped in the practical realization of many interesting experiments and has also opened up new fields of activities. Although there exist a large number of texts on optics, most of them do not discuss some of its modem aspects like coherence, holography, self-focusing, spatial frequency filtering, physics of lasers, etc. The present book gives a balanced account of traditional optics as well as some of the recent developments in this field.

The book has grown out of the lectures delivered by the author to the students at the Indian Institute of Technology, New Delhi. Care has been taken to develop the topics from the first principles so that the book can also be used for self-study; the underlying physical principles have also been emphasized.

Some special features of the book are given below:

1. Chapter 1, in addition to a brief historical introduction to the field of optics, tries to give a detailed discussion on the nature of light.

2. Chapter 2 studies the propagation of rays in inhomogeneous media and gives a fairly complete account of the phenomena of mirage and looming. Fermat’s principle has also been used to study the refraction of rays at the interface of an isotropic and an anisotropic medium.

3. It is now well known that, in addition to its elegance, the matrix method is a very convenient approach for the tracing of rays through complex optical systems; the third chapter develops this method to be used to study the image formation in simple optical systems. The matrix method has also been used in Chapter 22 to study the resonator systems employed in lasers.

4. In Chapter 6, expressions for the refractive index have been obtained from the first principles. The dependence of the refractive index on the wavelength has also been discussed. The fact that the ionosphere reflects electromagnetic waves of low frequencies and transmits electromagnetic waves of high frequencies has also been explained.

5. In Chapter 7, the Fourier integral theorem has been used to study the propagation and spreading of a wave packet. The actual spreading of a Gaussian wave packet in a dispersive medium has also been discussed.

6. Chapter 12 presents a detailed discussion on the localization of interference fringes.

7. The concepts of spatial and temporal coherence have been developed very carefully in Chapter 14 and the results of the recent experiments on optical beats have also been given.

8. Chapter 15, in addition to a detailed discussion on Fraunhofer diffraction, also discusses X- ray diffraction, self-focusing phenomenon and spatial frequency filtering; the latter two fields have received considerable attention after the development of the laser.

9. In Chapter 16, in addition to a fairly rigorous treatment of Fresnel diffraction, a careful analysis of the transition from the Fresnel region to the Fraunhofer region is also made.

10. In Chapter 17, the basic principle of holography and some of its applications have been discussed.

11. In Chapter 18, the polarization property of the electromagnetic waves has been discussed.

12. In Chapters 19 and 20, the solutions of Maxwell’s equations are studied from which the laws of reflection and refraction of plane electromagnetic waves by a plane dielectric and a plane metallic surface are derived. It has been pointed out that it is the frequency of the electromagnetic wave which determines whether a particular material would behave as a conductor or a dielectric. Chapter 20 also discusses evanescent waves which are generated when a beam undergoes total internal reflection.

13. In Chapter 21, the particle aspect of electromagnetic radiation has been discussed.

14. In the last chapter, the basic physics of a laser has been discussed in sufficient detail.

A large number of problems have been appended to each chapter and also references to articles and books for additional reading.

Although some of the topics discussed are somewhat of an advanced nature, they have been dealt with in a way by which even an undergraduate student should be able to comprehend them.

Ajoy Ghatak