Fourier-Transform Spectroscopy Instrumentation Engineering

Excerpt

This book covers the engineering aspects of Michelson-interferometer-based Fourier-transform (FT) spectrometers. While other Fourier-transform spectroscopy textbooks have generally focused on the theoretical aspects and applications, this book provides insights to the design and instrumentation of FT spectrometers. This book is intended for scientists and engineers who wish to understand the operation of the instrument to the extent where they have the knowledge to improve results through hardware, software and/or procedural modifications. This book is also a proper introductory text for an engineer who plans to design a custom FT spectrometer.

Many applications today require the FT spectrometer to perform close to its limitations, such as taking many quantitative measurements in the visible and in the near-infrared wavelength regions. In such cases, the instrument should not be considered as a perfect “black box.” Knowing where the limitations of performance arise and which components must be improved are crucial to obtaining repeatable and accurate results. One of the objectives of this book is to help the user identify the instrument's bottleneck.

The book begins with an overview of the types of spectrometers and the fundamental advantages of FT spectrometers (Chapter 1). Chapter 2 is devoted to clearly defining signal-to-noise ratio (SNR), a performance figure extensively used throughout this book. In Chapter 3, details of the interferometer operation are discussed. The design and limitations of the subsystems and components that include the motion components, the analog-to-digital (A/D) conversion process, the detection system, and the optical components are covered in Chapters 4 through 9. Chapter 10 introduces various practical techniques to identify the limiting source of error, and techniques to improve the obtainable SNR.

I am indebted to Professor Kamal Youcef-Toumi at Massachusetts Institute of Technology (MIT) for giving me the opportunities to be involved in various first-rate R&D projects during my time at MIT, one of which led me to the exciting world of FT spectroscopy. I deeply thank Merry Schnell of SPIE, the main editor of this project, for her thoroughness and professionalism. Bradley M. Stone and David Ball did an excellent job in reviewing the original manuscript. Rick Hermann and Timothy Lamkins of SPIE provided generous assistance from the early stage of the project. All have my deepest appreciation.

Vidi Saptari

September 2003