Absorption of Pulsed Terahertz and Optical Radiation in Earthworm Tissue and Its Heating Effect

Abstract

The transmission of THz, near-infrared (1030 nm), and green (515 nm) pulses through Eisenia andrei body wall is studied, which consists of epithelial layer and circular and longitudinal muscles. Samples with the full-body cross-section were also investigated. The transmitted power for the green pulses followed the Beer-Lambert law of exponential attenuation for all thicknesses and tissue structures. Different body wall and body center absorption coefficients were found in case of infrared pulses. In the THz range, the body wall absorption coefficient steadily increases from about 80 cm–1 at 0.2 THz to about 273 cm–1 at 2.5 THz. Numerical estimation indicates that THz pulses of 5-μJ energy and 1-kHz repetition rate (5-mW average power) cause only a small temperature increase of about 0.4 K, suggesting that heating has minor contribution to biological effectiveness.

Measurement and Modeling of the Optical Properties of Adipose Tissue in the Terahertz Range: Aspects of Disease Diagnosis

“…Refractive indices and absorption coefficients of water [ 2 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ], fat [ 3 , 4 , 10 , 36 , 52 , 53 , 54 , 55 , 56 , 57 , 61 , 62 , 63 , 64 , 66 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ], lipids [ 61 , 82 ], and main fatty acids [ 83 ] from the available literature are summarized in…”

Infrared laser ablation dynamics using light scattering

“…The rate of thermal diffusion in liver tissue can be estimated using a thermal diffusivity of 1.4 × 10 −7 m 2 s −1 [72,73] and assuming 75% water content [74,75], resulting in a thermal diffusion time of 13 µs, similar to that of glycerol. Thus the glycerol and tissue systems in this study are well within the limits of thermal confinement.…”

Mesotronics: Some New, Unusual Optical Effects

“…Note that obtaining super-resolution in the terahertz range, despite the scalability of the Maxwell equations, is a more difficult task than in optics. The main reason for this is much greater absorption (by 3-4 orders of magnitude) in the material than that in the optics [76][77][78]. It was shown for the first time [79] that the mesoscale dielectric particle allows increasing the resolution of the THz imaging system of arbitrary types [79][80][81][82][83][84] by simply placing it at the focused imaging points.…”