Table of Contents

Preface

 Acknowledgments

 Motivation

 Objectives

1 Fundamentals of Interference

1.1 Interference

     1.1.1 Interference by two wavefronts

1.2 Coherence Length

1.3 Laser Properties

1.4 Speckle Fundamentals

2 Speckle Interference and Displacement

2.1 Intensity Correlation for Open and Closed Fringes

2.2 Spatial Carriers in Speckle Interferometry for Open-Fringe Generation

2.3 Practical Removal of Environmental Instabilities

3 Electronic Speckle Pattern Interferometers

3.1 Out-of-Plane Electronic Speckle Pattern Interferometer

3.2 In-Plane Electronic Speckle Pattern Interferometer

     3.2.1 Generation of carrier fringes by rotation only

     3.2.2 Contouring

3.3 Shearography

     3.3.1 Carriers in shearography

     3.3.2 Contouring in shearography

4 Illumination and Displacement Detection

4.1 Illumination Using Two Simultaneous Light Sources

4.2 Three Sequential Illuminations Using a Single Light Source

     4.2.1 L-shaped sequential illumination

     4.2.1 Triangular sequential illumination

5 Transient Displacement Analysis

5.1 Recording Transient Events

     5.1.1 Recording a simple fast event

5.2 Recording Interferometric Events

5.3 Camera Acquisition and Synchrony Methods Using Pulsed Lasers

     5.3.1 Method 1: Single pulse per camera frame

     5.3.2 Method 2: Single-pulse time delay per camera frame

     5.3.3 Method 3: Twin pulses per two camera frames

     5.3.4 Method 4: Twin pulses per frame

6 Phase Detection

6.1 Carriers in Single-Shot Phase Detection

     6.1.1 Spatial synchronous detection

     6.1.2 Fourier transform method for difference of phase

     6.1.3 Carrier phase limits

6.2 Spatial Phase-Shifting Using Carriers

6.3 Phase-Shifting Using Four Quadrants in the Image Plane

6.4 Phase-Shifting in Adjacent Pixels Using Plarization

6.5 Heterodyne Interferometry

6.6 Phase-Shifting and Vortex Singularity Location

6.7 Temporal Phase Unwrapping

7 Overview of Applications

Appendix: Speckle Statistics

Index

Preface

Optics laboratory practices are the best way to understand the laws of physics that control the properties of electromagnetic waves and the way they interact with matter. As students start their journey on this science and perform optics experiments to harness the light features, it is always exciting to understand the mechanisms that allow us to measure physical properties using light. Light is everywhere and is part of our meaningful life. For the author, interacting with the universe through the use of light has been a joy and a journey of discovery. One of the aspects of electromagnetic waves that is most disconcerting is its interaction with rough surfaces that produce so-called speckle. This book is written for students who enjoy lab practices and look forward to dealing with, and understanding, speckle properties to find new ways of using them for measurement purposes.

Abundio Dávila
March 2022