The experiments presented in this book use highly coherent and monochromatic laser sources along with state of the art digital instruments and associated software. These have resulted in faster and easier laboratory experimentation and, therefore, the book would hopefully serve as a laboratory guide for the student community. In this respect, this book on employing digital technology is quite different from other textbooks/reference manuals on the subject. The unique approach of experimentation adopted in this book is quite different from those mentioned in other practical textbooks or manuals available on the subject.