Photothermal beam deflection is a well-established technique for measuring thermal diffusivity. A linear relationship that arises in this technique is that given by the phase lag of the thermal wave as a function of the distance to a punctual heat source when unidimensional heat diffusion can be guaranteed.
The heart of the system is a femtoseconds laser oscillator MAI TAI BB from spectra Physics. It generates pulses of ~ 80 Fs at 80 MHz between 710 and 980 nm. Processes taking place in time scales between pico and nanoseconds can be monitored with time resolution of hundred of femtoseconds.
The thermal lens (TL) effect is caused by deposition of heat through nonradiative decay processes after the laser excitation beam energy has been absorbed by a sample. This heat produces a local temperature change and forms a refractive index gradient that ultimately produces a lens of thermal nature in the sample.
Modulated photothermal reflectance (MPR) microscopy has become a very well established technique for the characterization of thermal properties of materials at the micrometer scale, as well as for the investigation of the heat source distribution in optoelectronic and microelectronic devices in operation.
The photothermal lens method (TL) measures the amount of heat generated by the absorption of the energy of a light pump beam, which generates a spatial refractive index gradient of thermal origin called a thermal lens. The thermal lens affects the propagation of a probe light beam, yielding distortions of its wave-front.
We developed a novel technique for obtaining the thermal diffusivity of a solid sample by combining the shadowgraph technique and the orthogonal skimming photothermal beam deflection technique. The method utilizes the shadow projected by the sample when put against a collimated light source.
We have two infrared cameras, the FLIR SC5000, working in the spectral region between 3 and 5 micrometers and the IR SmartEye 640, working between 7.5 and 13 microns.
When periodical modulated electromagnetic radiation interacts with matter a fraction of the energy is absorbed and converted into heat and this in turn leads to the generation of thermal waves (TW).
We developed an optical fiber based sensor for measurements of the refractive index () of liquids as a function of wavelength (). The principle of measurement is based on the detection of the intensity of reflected light.
Photoacoustic is a versatile technique with increasing applications to Chemistry and Physics. For example, a photoacoustic spectrum results from acoustic waves generated by the sample heating during the absorption of intensity modulated light, so that the photoacoustic spectroscopy technique is ideally suited for the study of opaque samples.
In the particular case of liquid samples, the photopyroelectric (PPE) technique has been emerged as one of the most useful methods for measurements of thermal properties, among other applications.
This technique is used for thermal conductivity measurements in liquids. It is based in the measurement of the temporal history of the temperature rise caused by a linear heat source (hot wire) embedded in a test material.
TPS 2500-S from Therm Test Inc. This technique is based in the transient hot plate method. The sensor head is sandwiched by two similar disc shaped solid samples or introduced in a sample in the case of liquids.
TWorkstation (IntelÂ® XeonÂ® CPU E5-2650 v2 @ 2.60 GHz â 2 processors; RAM: 64.0 GB) for high speed computing and digital imaging processing using MathCad, MathLab, COMSOL Multiphysics, Mathematica, MICROCAL ORIGIN, etc.
The LI-6400XT is LI-CORâs newest photosynthesis characterization system, which embodies the qualities as well as portability, ruggedness, flexibility, and a high level of hardware and software integration.
Ph.D. student Angel Cifuentes won one of the best poster awards given at the IX International Conference on Surfaces, Materials and Vacuum, which was held in MazatlÃ¡n, Sinaloa, Mexico, from September 26 to 30, 2016.
The âPhase Splitterâ Computer Program, developed by PhD Student Joan Jaime PuldÃ³n, was awarded with the Best Software Award of the Instituto PolitÃ©cnico Nacional, Mexico. This software, written with the collaboration of Drs. J. HernÃ¡ndez-Wong, A. CalderÃ³n and E. MarÃn, instruments the Phase Resolved Method for the analysis of Photoacoustic Spectra using the Hill Climbing Metaheuristic Algorithm.
Angel Sergio Cifuentes Castro received the 2017âs Best Thesis Award of the Instituto PolitÃ©cnico Nacional, Mexico, with his PhD Thesis entitled âContribution to materials thermal characterization techniques and subsurface defect detection using infrared thermography and other imaging methodsâ. Thesis advisors were Prof. E. MarÃn, from the Instituto PolitÃ©cnico Nacional, Mexico, and Prof. A. Salazar, from the Universidad del PaÃs Vasco, Bilbao, Spain. The thesis also received "Cum Lauden" awards from these universities.