Time-resolved Infrared Radiometry Research Articles

Infrared radiometry of dental enamel during Er:YAG and Er:YSGG laser irradiation

Time-resolved infrared (IR) radiometry was used to measure surface temperatures during pulsed Er:YSGG (l=2.79 mm) and Er:YAG (l=2.94 mm) laser irradiation of dental enamel. Scanning electron microscopy (SEM) was used to determine the melting and vaporization thresholds and to characterize other changes in the surface morphology. The magnitude and temporal evolution of the surface temperature during multiplepulse irradiation of the tissue was dependent on the wavelength, fluence, and pre-exposure to laser pulses. Radiometry and SEM micrographs indicate that ablation is initiated at temperatures well below the melting and vaporization temperatures of the carbonated hydroxyapatite mineral component (1200 °C). Ablation occurred at lower surface temperatures and at lower fluences for Er:YAG than for Er:YSGG laser irradiation: 400 °C vs. 800 °C and above 7 J/cm2 vs. 18 J/cm2, respectively. However, the measured surface temperatures were higher at l=2.79 mm than at l=2.94 mm during low fluence irradiation (<7 J/cm2). Spatially dependent absorption in the enamel matrix is proposed to explain this apparent contradiction.

Source patterning in time-resolved infrared radiometry (TRIR) of composite structures : Maclachlan Spicer, J.W.; Kerns, W.D.; Aamodt, L.C.; Murphy, J.C. Thermosense XIV. An International Conference on Thermal Sensing and Imaging Diagnostics Applications, Orlando, Florida (United States), 22–24 Apr. 1992, pp. 248–257. SPIE Vol. 1682 (1992)

Source patterning in time-resolved infrared radiometry (TRIR) of composite structures : Maclachlan Spicer, J.W.; Kerns, W.D.; Aamodt, L.C.; Murphy, J.C. Thermosense XIV. An International Conference on Thermal Sensing and Imaging Diagnostics Applications, Orlando, Florida (United States), 22–24 Apr. 1992, pp. 248–257. SPIE Vol. 1682 (1992)

Time-resolved infrared radiometry (TRIR) for characterization of impact damage in composite materials : Maclachlan Spicer, J.W.; Kerns, W.D.; Aamodt, L.C.; Murphy, J.C. Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.–2 Aug. 1991. Vol. 11A, pp. 443–440. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992)

Time-resolved infrared radiometry (TRIR) for characterization of impact damage in composite materials : Maclachlan Spicer, J.W.; Kerns, W.D.; Aamodt, L.C.; Murphy, J.C. Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.–2 Aug. 1991. Vol. 11A, pp. 443–440. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992)

Thermal Characterization of Heat Sink Adhesive Systems for Spacecraft Electronics by Time-Resolved Infrared Radiometry

A new thermal characterization technique, time-resolved infrared radiometry (TRIR), is used to investigate three different heat sink adhesive systems used in spacecraft electronics - a filled epoxy, a filled silicone and a tape adhesive. Measurements of heat sink efficiency are presented as a function of thermal cycling and the TRIR results are compared with ultrasonic and X-ray imaging techniques and with destructive analysis. The TRIR technique is shown to provide a measure of the relative heat sink capabilities of the different systems and can detect subsurface delamination in the filled epoxy system resulting from the development of cracks due to thermal cycling.

Analysis of characteristic thermal transit times for time-resolved infrared radiometry studies of multilayered coatings

Time-resolved infrared radiometry (TRIR) has been shown to be a valuable thermal characterization technique for the nondestructive evaluation of layered coatings. In this method an external step heating pulse is applied to the coating system and the resulting change in surface temperature is monitored as a function of time. Characteristic times and amplitudes can be ascribed to internal thermal reflections that return heat to the coating surface. A full description of the time dependence of the coating surface temperature can be obtained from these quantities. This paper describes a method for determining these characteristic times and amplitudes and shows their relationship to internal heat-flow patterns. Uses and limitations of the method are discussed, and comparison of the theory with experimental TRIR results is presented.