Photothermal lens spectrometry measurements in highly turbid media.
We measured the photothermal lens signal in samples exhibiting high turbidity using a pump-probe scheme. We show that the photothermal lens signal properties remain nearly unchanged up to values of turbidity of 6 cm(-1) despite the signal reduction due to the decrease of excitation power associated to turbidity losses. The signal starts decreasing abruptly for values of turbidity larger than 6 cm(-1). Multiple light scattering yields a reduction of the temperature gradients, which results in a decrease of the effective signal. However, the signal-to-noise ratio remains above 50 for turbidity values of 9 cm(-1), which corresponds to a reduction of light transmission by more than four orders of magnitude. We report on the detection of the photothermal lens signal through a 2 mm layer of organic tissue with a signal-to-noise ratio of about 500. This technique appears promising for imaging applications in organic samples, which usually exhibit high turbidity for visible and near-infrared light.
Delaware State University, Department of Physics and Engineering and Optical Science Center for Applied Research, 1200 North Dupont Highway, Dover, DE 19901 USA.
Aristides
A
Marcano
Isaac
I
Basaldua
Aaron
A
Villette
Raymond
R
Edziah
Jinjie
J
Liu
Omar
O
Ziane
Noureddine
N
Melikechi
D000818:Animals; D002645:Chickens; D007909:Lenses; D008027:Light; D018482:Muscle, Skeletal / Q000737:chemistry; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation / Q000379:methods*; D012542:Scattering, Radiation; D059629:Signal-To-Noise Ratio; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D013816:Thermodynamics