Statistics – Applications
Scientific paper
Jan 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990phdt........40f&link_type=abstract
Thesis (PH.D.)--STANFORD UNIVERSITY, 1990.Source: Dissertation Abstracts International, Volume: 51-08, Section: B, page: 3907.
Statistics
Applications
Microscopy
Scientific paper
Photothermal microscopy is a technique for measuring thermal properties on a small scale by using focussed laser beams as heat sources and as temperature probes. Typically used for nondestructive evaluation (NDE) of materials, its main advantage is its ability to measure types of flaws that are not visible optically or acoustically. Examples of these kinds of defects include disbonds and poor adhesion in layered media, subsurface cracks or crystal damage in opaque solids, and electrical defects in active circuits. The greatest limitation of these systems is their relatively poor signal-to-noise ratios and, consequently, slow imaging speeds. To circumvent this problem, a variety of approaches to the detection of thermal waves has been pursued in recent years. This thesis compares the relative merits of a common class of techniques that rely on direct observation of physical changes in the heated sample, including a novel approach to interferometric measurement of the thermal expansion. It is found that the optimum approach depends not only on the physical properties of the sample being studied, but also upon the resolution of the experiment and the damage threshold of the specimen. These points are illustrated in an assortment of examples of photothermal NDE. Finally, this dissertation describes our applications of photothermal microscopy to the study of the anisotropic thermal properties of the new high-T_{ rm c} superconductors. Because of their micron resolution, photothermal techniques are well suited for studying single-crystal specimens which tend to be too small or irregularly shaped for conventional bulk methods. Our measurements of the anisotropic thermal conductivity demonstrate that the heat flow along the superconducting planes is enhanced below the transition, and that no such enhancement exists in the non-superconducting direction. These effects can be explained as a product of the electron-phonon coupling. Furthermore, we present evidence that thermal and optical changes in these materials can begin as much as 10 or 15 K above the superconducting transition.
No associations
LandOfFree
Analysis and Applications of Photothermal Microscopy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Analysis and Applications of Photothermal Microscopy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Analysis and Applications of Photothermal Microscopy will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1564296