Applied Physics & Optics

Members of the department pursue research in the following Applied Physics and Optics areas.

 


Thermal and Optical Materials Characterization

Emeritus Professor Pao-Kuang Kuo

A new research area is probe-based microscopy. Both the Atomic Force Microscope (AFM) and the apertureless near-field optical microscope (ANSOM) make extensive use of the optical and scanning skills developed in the research of photothermal phenomena. Ongoing research includes both theoretical and experimental aspects of nanoelasticity studies and light concentration on a mesoscopic scale.


Thermal Wave Imaging

Professors Robert L. Thomas, L.D. Favro (emeritus), and Xiaoyan Han (ECE)

The Thermal Wave Imaging research group utilizes infrared and visible optical techniques, that are applied to problems involving optical absorption, and the diffusive scattering of both thermal and photon density waves. These experiments involve imaging subsurface structures with industrial and medical applications, as well as the quantitative characterization of the thermal and optical properties of materials. The group pioneered both the theory and the experimental technique of thermal wave imaging. This imaging technique uses time-varying heat sources, together with synchronous surface temperature detection, to carry out sub-surface material characterization and imaging.

thermal image

Nine patents have resulted, several of which have been licensed, and a successful local company was formed to utilize and market the technology. The group has elucidated the theory of thermal wave scattering, with confirming experimental work, leading to fourteen Ph.D. dissertations since 1981. During this period, the research has received funding from the Army, the Air Force, the Navy, the FAA, and numerous companies.

An important recent application of the group's research has been the development of one-sided thermal wave measurements of the thickness of materials. The motivation of this work was to provide a basis for the development of practical tools for finding and quantifying defects in metals and composite materials, and for process control applications in automotive and aerospace industries. The research resulted in the development of algorithms for quantitative thermal wave defect depth and thickness measurements. An imaging system using these algorithms is now being evaluated by Boeing and the FAA as an alternative to conventional inspection techniques for detection and measurement of corrosion and disbonds in aging aircraft. These algorithms are currently in use by the US Air Force in Georgia for inspecting F-15's, C-130's and C-141's, and in Oklahoma City for inspecting KC-135's and B-52's, and by Nordam in Tulsa, to inspect composite structures in commercial aircraft.

Experimental equipment used by the group includes several Ar-ion lasers (up to 20 W), a CO/CO2 laser, 2 Nd/YAG lasers, a 16-W diode laser with a fiber optic delivery system, a number of high pointing stability probe lasers, and six high quantum efficiency InSb focal-plane-array IR imaging systems.