Share Email Print

Spie Press Book • on sale

Applications of Lock-in Amplifiers in Optics
Author(s): Gerhard Kloos
Format Member Price Non-Member Price

Book Description

Lock-in amplifiers are key devices in numerous instruments used in the optical sciences or in optical equipment in industry. In many experimental configurations, they represent the means to reliably detect and record small or weak signals. The purpose of this text is to provide a step-by-step introduction to this technique. The first part explains how modulation is used to extract a signal from noise and describes different types of modulation. The focus shifts from electronics to optics in the second part, which covers lock-in amplifier applications in optical instruments. The book is intended for readers who want to better understand instruments and experiments based on lock-in detection and/or to design (and perform) new experiments in which lock-in amplifiers are applied.


Book Details

Date Published: 10 January 2018
Pages: 118
ISBN: 9781510617087
Volume: TT117

Table of Contents
SHOW Table of Contents | HIDE Table of Contents

Table of Contents

Preface

1 Introduction

2 Basic Concepts
2.1 Phase-Locked Loop
2.2 Multiplication and Filtering
      2.2.1 Sinusoidal signal and reference
      2.2.2 Square-wave signal and reference
      2.2.3 Square-wave reference signal and comb-filter effect
      2.2.4 Summary and overview
2.3 Nonlinearlities and Higher Harmonics
      2.3.1 Detection at multiples of the frequency of the first harmonic
      2.3.2 Intermodulation
2.4 Two-Phase Systems
      2.4.1 Quadrature
      2.4.2 Vector computer
      2.4.3 Vector tracking
2.5 Measuring Higher-Order Derivatives
2.6 Operating the Lock-in Amplifier
2.7 External Noise Sources
References

3 Optical Spectroscopy
3.1 Absorption Spectroscopy
      3.1.1 Single-beam spectrometers
      3.1.2 Two-beam spectrometers
      3.1.3 Frequency modulation
3.2 Fluorescence Measurements
      3.2.1 Fluorescence spectroscopy
      3.2.2 Fluorescence lifetime imaging
3.3 Phosphorescence Spectroscopy
3.4 Outlook: Advanced Laser Spectroscopy
References

4 Optical Interferometry
4.1 Michelson Interferometer
4.2 Kösters Interferometer
4.3 Mach–Zender Interferometer
4.4 Jamin Interferometer
4.5 Spherical Fabry–Pérot Interferometer
4.6 Conclusion
References

5 Crystal Research and Technology
5.1 Magneto-optic Effects
      5.1.1 Faraday effect
      5.1.2 Magneto-optic Kerr effect
5.2 Electromechanical Cross-Effects
      5.2.1 Piezoelectricity
      5.2.2 Quadratic electrostriction and Maxwell stresses
5.3 Electro-optic Effects
      5.3.1 Linear electro-optic effect: the Pockels effect
      5.3.2 Quadratic electro-optic effect: the Kerr effect
References

6 Infrared Thermography
6.1 Photothermal Radiometry
6.2 Optically Induced Lock-in Thermography
6.3 Ultrasonic Lock-in Thermography
References

7 Laser Wavelength Stabilization
7.1 Laser Stabilization using a Fabry–Pérot Cavity
7.2 Laser Containing a Gas Absorption Cell
References

8 Advanced Microscopy
8.1 Scanning Tunneling Optical Microscope and Fabry–Pérot Interferometer
8.2 Polarization-Contrast Confocal Microscope
8.3 Scanning Tunneling Microscope and Photothermal Displacements
References

9 Other Applications
References

Index

Preface

Lock-in amplifiers are key devices in numerous instruments used in the optical sciences and in optical equipment in industry. In many experimental configurations, they represent the means to reliably detect and record very small signals that are superimposed by noise.

The purpose of this text is to provide a step-by-step introduction to the technique of phase-sensitive detection using lock-in amplifiers, and to provide examples of its applications in optical instruments. The book begins by explaining the basics of how modulation is used to extract a signal from noise. Different types of modulation are discussed in detail and are compared. The book then presents the various applications of lock-in amplifiers in optical instruments, and the focus shifts from electronics to optics.

Some of the covered optical applications of lock-in amplifiers are optical spectroscopy, including absorption spectroscopy, fluorescence spectroscopy, and phosphorescence spectroscopy; optical interferometry, including detailed presentations of the various spectrometers used with lock-in amplifiers; crystal research and technology, including explanations of magneto-optical, electromechanical, and electro-optical effects; infrared thermography; laser wavelength stabilization; and advanced microscopy.

The book is intended for readers who want to better understand instruments and experiments based on lock-in detection and/or to design (and perform) new experiments in which lock-in amplifiers are applied.

Gerhard Kloos
January 2018


© SPIE. Terms of Use
Back to Top