講演情報
[17a-K209-7]Experimental and theoretical development of photothermal heterodyne transmission imaging
〇Stephane Chevalier1,2,6, Meguya Ryu3, S Kamegaki5, Jordan Letessier6, Jeremie Maire6, Jean-Christophe Batsale6, Junko Morigawa4 (1.IIS-UT, 2.ENSAM, 3.NMIJ, 4.IST, 5.IIR, 6.CNRS)
キーワード：
Infrared imaging、heat transfers、thermotransmittance
Heterodyne photothermal imaging (PHI) measurements are commonly used to characterize thermal properties (diffusivity, conductivity) or to analyze the chemical composition of materials by spectroscopy on small scales (1 - 100 µm) [1]. In general, these studies are based on thermoreflectance, typically combining an infrared pump laser with a visible probe laser for better spatial resolution. However, these techniques are limited to the study of heat and mass transfers at the surface or in thin materials (isothermal assumption in thickness) [2].
In this study, we present a new imaging method based on the transmission signal of materials excited by an infrared pump, offering key advantages: it is suitable for non-reflective and non-transparent materials in the visible (e.g. silicon), has better sensitivity for measurements in materials such as PDMS and water, and allows characterization of sub-surface heat sources [3]. We have developed a transmission PHI (PHTI) measurement system comprising a light emitted from the slit (output of the monochromator), λ = 3 - 5 µm). By analyzing variations in optical transmission, we determined and identified thermotransmittance (κA) and thermoreflectance (κR) coefficients for three materials: Borofloat glass, PDMS and water. These measurements enabled us to map temperature rise fields at microscale with Kelvin-level accuracy in samples of different thicknesses, including buried water thin films (≤ 100 µm). This approach has been validated by an analytical 1D thermal model and is proving particularly effective for microfluidic applications where conventional reflection methods are inapplicable.
In this study, we present a new imaging method based on the transmission signal of materials excited by an infrared pump, offering key advantages: it is suitable for non-reflective and non-transparent materials in the visible (e.g. silicon), has better sensitivity for measurements in materials such as PDMS and water, and allows characterization of sub-surface heat sources [3]. We have developed a transmission PHI (PHTI) measurement system comprising a light emitted from the slit (output of the monochromator), λ = 3 - 5 µm). By analyzing variations in optical transmission, we determined and identified thermotransmittance (κA) and thermoreflectance (κR) coefficients for three materials: Borofloat glass, PDMS and water. These measurements enabled us to map temperature rise fields at microscale with Kelvin-level accuracy in samples of different thicknesses, including buried water thin films (≤ 100 µm). This approach has been validated by an analytical 1D thermal model and is proving particularly effective for microfluidic applications where conventional reflection methods are inapplicable.