Advisor(s)

Charles A. DiMarzio

Contributor(s)

Gregory J. Kowalski, Carey M. Rappaport

Date of Award

2010

Date Accepted

8-2010

Degree Grantor

Northeastern University

Degree Level

M.S.

Degree Name

Master of Science

Department or Academic Unit

College of Engineering. Department of Electrical and Computer Engineering.

Keywords

biomedical, cancer, imaging, microscopy, photothermal, thermoelastic

Disciplines

Electrical and Computer Engineering | Engineering

Abstract

This research, through a rigorous optical, thermal and mechanical computational analysis, demonstrates the use of Photothermal Microscopy to tag light from the focus, and thereby improve contrast and depth of imaging limited by out--of--plane scatter.

The photothermal effect produced by the conversion of optical energy to heat within a dielectric medium provides a basis for investigation of the optical absorption and thermal characteristics of a sample. Through application of Photo-acoustic spectroscopy, measurements can be made of the acoustic pressure wave resulting from the absorption within the medium from a heating laser. This technique is commonly employed in biomedical imaging, however, it lacks the resolution necessary to image human skin at a cellular level.

To improve the resolving power and achieve adequate depth, this research demonstrates, computationally, the implementation of a coherent confocal microscope into the photo-acoustic system. The high accuracy of the interferometer in the confocal microscope allows for detection of small changes in position of scattering particles within the skin. Information about the optical phase of the particles can be obtained from measurement of the Doppler shift from these displacements due to the thermoelastic expansion of the sample by the photothermal process. This technique resembles the Doppler Laser Radar, an inherent concept implemented into the coherent confocal microscope.

The results of the computational analysis of this research are compared to analytical and theoretical expectations and are found to be in good agreement.

Document Type

Master's Thesis

Rights Information

Copyright 2010

Rights Holder

Jason M. Kellicker


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