We have developed a method of the terahertz (THz) solid immersion microscopy for the reflection-mode imaging of soft biological tissues. It relies on the use of the solid immersion lens (SIL), which employs the electromagnetic wave focusing into the evanescent-field volume (i.e. at a small distance behind the medium possessing high refractive index) and yields reduction in the dimensions of the THz beam caustic. We have assembled an experimental setup using a backward-wave oscillator, as a source of the continuous-wave THz radiation featuring λ= 500 μm, a Golay cell, as a detector of the THz wave intensity, and a THz SIL comprised of a wide-aperture aspherical singlet, a truncated sphere and a thin scanning windows. The truncated sphere and the scanning window are made of high-resistivity float-zone silicon and form a unitary optical element mounted in front of the object plane for the resolution enhancement. The truncated sphere is rigidly fixed, while the scanning window moves in lateral directions, allowing for handling and visualizing the soft tissues. We have applied the experimental setup for imaging of a razor blade to demonstrate the advanced 0:2λ resolution of the proposed imaging arrangement. Finally, we have performed imaging of sub-wavelength-scale tissue spheroids to highlight potential of the THz solid immersion microscopy in biology and medicine.
We revealed that after exposure of scarified cornea of rabbits to low-intensity pulsed terahertz radiation 0.1 to 1.8 THz a positive effect on epithelization triggered within the first hours was higher compared to non-irradiated cornea. However, while elevating power of terahertz radiation up to 60.8 nW it resulted in retarding epithelialization process. At that, irradiation did not affect timeframe of complete corneal epithelialization. During experiments it was found that terahertz radiation was well tolerated, exhibited no toxic and allergic reactions or resulted in pathohistological changes in the eye tissues. Also, low-intensity terahertz radiation did not affect normal physiological functions of the eyes and facilitated to re-epithelialization of scarified eyes in rabbits.
The optical properties of normal fibroblasts and fibroblasts cultured with cancer cells were studied in the frequency range of 0.2 - 1.0 THz. The results show the possibility to distinguish healthy cells from corrupted ones using their optical parameters.
It was revealed correlation between the optical density of the lens’s nucleus in terahertz range with its density,
determined according to the L. Buratti classification. Consolidation of the lens fibers caused by senile cataract, increases the reflectivity of the lens in the THz range. The temporal structure of reflected THz signals allows to determine the spatial distribution of density in the lens.
Application of terahertz radiation for the creation of medical equipment and solving of biological problems has become
widely spread. From this point of view, the influence of THz radiation on the nerve fibers is of primary concern. In
addition, several studies indicated both stimulating and depressive effects on nerve cells. However, the mechanism of
this effect has not yet been studied, including the dose and exposure time. Our research was devoted to the impact of
broadband pulsed THz radiation in the frequency range of 0.05 to 2 THz on the neurite growth in the sensory ganglia of
10-12-day chicken embryos. Dependence of changes in functional responses of cells on the average output power has
been found. An increase in the stimulating effect was observed at the lowest power density used (0.5 μW/cm<sup>2</sup>). Through
non-destructive process and choosing the correct parameters of THz radiation, potential control of neural response
becomes possible, which can subsequently lead to new medical treatments.
In the present paper research results of broadband THz radiation influence in a range 0.1÷2 THz on some biological tissues
are presented. Theoretical modeling of THz radiation propagation through the fat sample is performed. Experimental
absorption spectra of samples of vegetable oil, nail tissue, skin tissue and blood are obtained. Spectra of these tissues differ
in a range of 0.1 ÷ 2 THz. Also they depend on water content. From these samples vegetable oil has the best transmission.
The study of thermoinduced changes of optical properties of adipose tissue is very actual problem. We made the optical
model of thermo-sensitive heterophase medium (adipose tissue). Here the elementary adipose cell will consist of a cube
which basic volume will contain a adipose ball, everything else- water. The adipose ball will contain liquid and crystal
phases. Has been created the experimental scheme for research of angular distribution of the light passed through the
adipose tissue sample. The same model has been created in program Tracepro - General Raytracing. It is presented the
good coordination of calculated and experimental curves for temperatures 5, 26 and 40 °C. We have made a calculated
curve of dependence of intensity transmitted through the multyphase medium (adipose tissue) from a ratio of volume of
liquid phase to total volume. Experimentally knowing also, that intensity of transmitted light depends on temperature,
we have made the dependence of a ratio of volume of a liquid phase to total volume of a cell from temperature. Also we
have put the experiment. We have keep the sample of adipose tissue at temperature 20, 30 and 39 °C in drying box. And
we have received a ratio of hard and liquid phases in the sample. Thus the dependence of observed in experiment
intensity on temperature can be caused by dependence of a ratio of volume of liquid and hard phases in the medium on
The goal of the present paper is to find a connection between time-point of fat tissue removal out of a human organism, rotation angle of polarization plane and optical transmission as well. The authors determined experimentally that <i>in vitro </i>fat tissue rotates polarization plane of linearly polarized light at temperature of 24 °C. At that as left- and right-rotation of polarization plane is observed. Value of rotation angle rises proportionally in time of <i>in vitro </i>specimen keeping up. The authors defined a connection of this phenomenon to features of polymorphous structure of a fat tissue.
One of the most attractive perspectives for modern medicine is to solve a problem of a superfluous weight. Method of solving the problem by means of a light source initiates to study optical characteristics of fatty tissue in details. This paper studies temperature dynamic of IR, NIR and visible spectrum of fatty tissue. It refers to temperature, spectra absorption bands and aggregation state of fatty tissue. Character of spectrum changes close to temperatures complying with the change of in-vitro fatty tissue condition is a subject of author’s particular attention.
The problem of a superfluous weight is extremely exciting for a modern cosmetology. The solution of the problem by application of light sources is quite difficult if no optical characteristic of a fat tissue is known. This paper studies a temperature dynamics of full, collimated and diffuse and scattering flows of non-coherent polychromatic light came through an <i>in vitro</i> lard sample. On experimenting the authors found a sharp degradation of in vitro lard sample scattering properties at a temperature of 25±1°C.