This new edition is thoroughly revised and updated as per the latest syllabus of JNTU, Kakinada. Some new topics which are relevant and beneficial for the students like Wedge Angle; Space of Thickness; Huygen's Wave Theory; Differences Between Polarized and Ordinary Light; Bragg's Conditions; Advantages of Debye-Scherrer Method; Intermodal Dispersion and Types of Scans have been added. Previous Years' Question Papers and an additional set of Multiple Choice Questions have also been given at the end of the book to make it more useful and student friendly. The entire text has been organized into eight chapters dealing with several branches of Physics like Optics, Crystal Structure, X-Ray Diffraction, Optical Fibre, Laser and Non-Destructive Testing using Ultrasonics. Chapter 1 deals with interference, physical properties of light, Fresnel's Biprism, application of interference like thin films, Newton’s Ring, etc.Chapter 2 comprises of diffraction, need of diffraction, production of diffraction pattern and the study of its intensity distribution, applications of diffraction in various devices within the framework of syllabus.Chapter 3 discusses polarization and how polarization is useful to know the types of the wave light, direction of vibration of waves and the different ways by which the polarized light can be produced, different applications of polarization like production of different types of polarized light from plane polarized light, specific rotation, optical activity, etc. Chapter 4 deals with crystal structure with all the possible types of crystals and determination of the actual structure of the crystalline solids. Chapter 5 gives insight into X-ray diffraction along with all related phenomena of X-rays.Chapter 6 consists of laser and its characteristics, relation between Einstein's coefficients, types of laser and its application in industry, scientific and medical fields.Chapter 7 deals with fibre optics, principle and types of optical fibres, different modes of communication through optical fibres and its use in industry, advantages of hologram over conventional photography, construction and reconstruction of hologram and its application in industry. Chapter 8 provides recent advances about non-destructive, testing using ultrasonics basic principles of ultrasonic testing, electromagnetic acoustic transducers, production, properties and applications of ultrasonic waves.