Graduation Year

2006

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Electrical Engineering

Major Professor

Luis García-Rubio, Ph.D.

Co-Major Professor

Wilfrido Moreno, Ph.D.

Committee Member

Grisselle Centeno, Ph.D.

Committee Member

Miguel Labrador, Ph.D.

Committee Member

James Leffew, Ph.D.

Committee Member

José Olivares, Ph.D.

Keywords

Modeling, Signal Processing, Compensation, Optical Effects, Simulation

Abstract

This dissertation describes an approach and a model for the analysis of critical parameters related to the optical and electronic components of spectroscopy systems. The model described herein enables a systematic study of the impact of these parameters on the total performance of the system; therefore, it is a tool for the design and optimization of spectrometers.

Although the physics of the optical and electronic components in spectroscopy systems are known and well established, the systemic approach to the understanding of their interactions is recent and it is an area of active research. The results from this study are at several levels: from an engineering perspective, the method developed based on an integrated spectroscopy model enables not only the study of the interactions between the components of the spectrometer, but also the design and optimization of spectrometers for specific applications. From the signal analysis point of view, the understanding of the interactions between components enables a better identification and filtering of the noise. From the applications point of view, the resulting integrated model enables the translation of data between different spectrometer systems through appropriate compensation algorithms.

The approach followed in this dissertation is based on the integration of the models of each one of the components of a spectro-photometer: slit, grating, collimating elements, photo-detectors and analog-to-digital converters. An important contribution of this research has been the simplification of the diffraction grating model. The simplification of the diffraction grating model enables the implementation of a general spectrometer model with two important characteristics: first, it facilitates the analysis of the effect of the parameters of the spectrometer on the spectra readings; second, it allows a computational efficient simulation of the complete model of the spectrometer.

The simplified spectrometer model presented in this dissertation predicts the instrumental effects detected in observed spectra. The results obtained with the model are validated against measured spectra of polystyrene particles suspended in de-ionized water. It is demonstrated that the integrated spectrometer model is capable of representing all the instrumental effects identified.

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