A model for cw laser induced mode-mismatched dual-beam thermal lens spectrometry

Top-hat cw laser induced thermal mirror: a complete model for material characterization

“…in which B is a constant [19], g = (r/ω 1P ) 2 and V = Z 1 /Z C [23]. For the BLM and HAM Φ(g,t) can be expressed as…”

Characterization of Biodiesel by Unconventional Methods: Photothermal Techniques

“…Thermal Lens Spectrometry (TLS) is one of a family of photothermal techniques that can be used to measure spectroscopy and thermooptical properties of transparent materials (Cruz et al, 2011, Franko 2002, Sampaio et al, 2002, Bialkowski, 1996, Shen et al, 1992, Baesso et al, 1994. This technique has proved to be high sensitive and accurate, it is approximately three orders more sensitive than conventional transmission methods.…”

“…The temporal evolution of the on-axis probe beam intensity, I(t), is measured in the far field using a circular aperture in front of a photodiode. Shen et al using the Fresnel diffraction theory, determined an analytical expression for the probe beam intensity at the detector (Shen et al, 1992 …”

“…A portion of energy is absorbed and its conversion into heat generates a radial temperature profile into the sample, which consequently gives rise to a refraction index profile. The temporal evolution of such thermal lens is strictly related to optical and thermal properties of the sample and is detected by a probe beam, which impinges in a photodiode after passes through the sample (Shen et al, 1992). In the photopyroelectric technique, the thermal waves are produced by the absorption of radiation with modulated intensity and detected by a pyroelectric transducer, which is a polymeric or ceramic material, in contact with the sample.…”

Interferometry and thermal lens experimental method for studying the axial heat propagation in liquid samples

“…Debido a la absorción del haz, se genera una distribución de temperatura que induce un cambio local en el índice de refracción del medio [1][2][3]. Si el haz del láser es radialmente de tipo Gaussiano, entonces la distribución de temperatura inducida conserva el perfil del haz de excitación.…”