Introduction to Optical Metrology

Rajpal S. Sirohi

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351831116
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Introduction to Optical Metrology examines the theory and practice of various measurement methodologies utilizing the wave nature of light. The book begins by introducing the subject of optics, and then addresses the propagation of laser beams through free space and optical systems. After explaining how a Gaussian beam propagates, how to set up a collimator to get a collimated beam for experimentation, and how to detect and record optical signals, the text:

• Discusses interferometry, speckle metrology, moiré phenomenon, photoelasticity, and microscopy
• Describes the different principles used to measure the refractive indices of solids, liquids, and gases
• Presents methods for measuring curvature, focal length, angle, thickness, velocity, pressure, and length
• Details techniques for optical testing as well as for making fiber optic- and MEMS-based measurements
• Depicts a wave propagating in the positive z-direction by e i(?t – kz), as opposed to e i(kz – ?t)

Featuring exercise problems at the end of each chapter, Introduction to Optical Metrology provides an applied understanding of essential optical measurement concepts, techniques, and procedures.

1	Introduction to Optics

1.1 INTRODUCTION

Metrology is the science and technology of making measurements and drawing significant conclusions from a set of data. Optical metrology uses light-based techniques for measurement. The majority of measurements involve length in one form or other and hence most of the techniques reported in this book will relate to length measurement. Besides, there are some physical parameters of direct relevance in optics and hence the techniques of measurement of these parameters will also be included in the text.

Length is expressed in meters. Prior to 1889, the meter was defined as 1/10,000,000 the distance between the North Pole and the equator along the line of longitude passing through Paris, France. A platinum bar of length equal to the meridional definition of the meter was to be the prototype meter (end standard). The end standard meter was found impracticable due to wear of the ends to ensure international reproducibility and hence was replaced by the line standard. The standard meter is defined as a length between two fine lines engraved on a platinum-iridium bar of an X cross section maintained and measured under very accurately controlled conditions. It remained in force from 1889 to 1960. However, because of the everpresent threat of natural disaster damaging the physical artifact, the standard based on the platinum-iridium bar was replaced by a standard based on the wavelength of light. The length of 1,650,763.73 times the wavelength of the orange-red line in the emission spectrum of ⁸⁶Kr was accepted as a standard meter; this definition remained in force from 1960 to 1984.

During this period, several other laser sources became the contenders for the length standard. In 1983, the 17th Ge...