A laser induced photoacoustic technique has been employed to measure the thermal effusivity value of natural rubber latex
in the liquid as well as in the solid state. The nano Zinc Oxide particles synthesized via precipitation technique is incorporated to the
natural rubber latex. The influence of molar fractions of nanoparticles on the thermal effusivity value of host polymer is investigated.
Detailed analysis of the results shows that the rubber latex in the solid state exhibits lower value for the thermal effusivity value in
comparison to the liquid state. The molar fraction of the nanoparticle is found to influence the effective thermal effusivity value in a
substantial manner. Results are explained in terms of nanoparticle and phonon assisted thermal energy transport in these samples.
A laser induced thermal lens technique has been employed to evaluate the dynamic thermal parameter, the thermal
diffusivity, of gold nanofluids. Gold nanoparticles were synthesized by citrate reduction of HAuCl<sub>4</sub> in water. The UVVIS
optical absorption spectra show an absorption peak around 540 nm owing to surface Plasmon resonance band of the
gold particles. The thermal diffusivity of gold nanoparticles was evaluated by knowing the time constant of transient
thermal lens obtained by fitting the experimental curve to the theoretical model of the mode-matched thermal lens.
Analyses of the results show that the nanofluid exhibits lower thermal diffusivity value in comparison to the host
medium, water. Further investigations also reveal that the concentration of nanoparticles in the fluid have influence on
the measured thermal diffusivity value. Results are interpreted in terms of interfacial thermal resistance around the
nanoparticles as well as on the clustering of nanoparticles.
An open cell photoacoustic configuration has been employed to evaluate the thermal diffusivity of pure InP as well as InP doped with sulphur and iron. Chopped optical radiation at 488 nm from an Ar-ion laser has been used to excite photoacoustic signals which been detected by a sensitive electret microphone. Thermal diffusivity value have been calculated from phase versus chopping frequency plots. Doped sample are found to show a reduced value for thermal diffusivity in comparison with intrinsically pure sample. The results have been interpreted in terms of the mechanisms of heat generation and transmission in semiconductors.
A sensitive method based on the principle of photothermal lensing technique to realize optical logic gates is presented. A dual beam thermal lens method using low power cw lasers can be very effectively used as an alternate technique to perform the logical function such as XOR and NAND.