Presenter Information

Andrew C. Tam, IBM

Location

La Jolla ,CA

Start Date

1-1-1989 12:00 AM

Description

Photothermal (PT) effects are produced by the heating a sample and its surroundings due to the absorption of electromagnetic radiation, and is a type of energy conversion. Using a laser beam for PT generation, many PT effects can be measured, including refractive-index gradients, acoustic emission, surface deformation, reflectivity changes, desorption, and “grey-body” infrared emission, providing useful techniques for materials characterization. These PT material probing or characterization techniques generally rely on the use of high-sensitivity detection methods, involving the use of “probe” laser beams, transducers, or infrared detectors to monitor the effects caused by PT heating of a sample. Many of these PT effects occur simultaneously, e.g., PT heating of a sample in air will produce temperature rise, photoacoustic waves and refractive-index changes in the sample and in the adjacent air, infrared thermal radiation increase, etc., all at the same time. Thus, the choice of a suitable PT effect for detection will depend on the nature of the sample and its environment, the light source used, and the measurement desired. We have previously reviewed [1,2,3] the various experimental arrangements and detection schemes for the different PT effects, and given a summary of possible applications. We have shown that it is possible to obtain high PT generation efficiencies using a short-pulsed laser beam; various sensitive detection schemes have also been developed to monitor the resultant temperature or pressure transients in the sample or its vicinity.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

8A

Chapter

Chapter 2: Advanced Techniques

Section

Laser Ultrasonics

Pages

473-487

DOI

10.1007/978-1-4613-0817-1_60

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Photothermal Techniques in Material Characterization Applications

La Jolla ,CA

Photothermal (PT) effects are produced by the heating a sample and its surroundings due to the absorption of electromagnetic radiation, and is a type of energy conversion. Using a laser beam for PT generation, many PT effects can be measured, including refractive-index gradients, acoustic emission, surface deformation, reflectivity changes, desorption, and “grey-body” infrared emission, providing useful techniques for materials characterization. These PT material probing or characterization techniques generally rely on the use of high-sensitivity detection methods, involving the use of “probe” laser beams, transducers, or infrared detectors to monitor the effects caused by PT heating of a sample. Many of these PT effects occur simultaneously, e.g., PT heating of a sample in air will produce temperature rise, photoacoustic waves and refractive-index changes in the sample and in the adjacent air, infrared thermal radiation increase, etc., all at the same time. Thus, the choice of a suitable PT effect for detection will depend on the nature of the sample and its environment, the light source used, and the measurement desired. We have previously reviewed [1,2,3] the various experimental arrangements and detection schemes for the different PT effects, and given a summary of possible applications. We have shown that it is possible to obtain high PT generation efficiencies using a short-pulsed laser beam; various sensitive detection schemes have also been developed to monitor the resultant temperature or pressure transients in the sample or its vicinity.