Method of generating a pulsed X-ray

Abstract

Nonlinear optical effects in lattice SiO 2 nanosphere packings under pulse laser excitation are experimentally studied. Pulse generation of narrow-beam X-ray radiation is determined in this samples. The possibility of using this effect in medicine are considered.The studies relates to the field of Radiological, and can be used in medicine, medical imaging, inspection of materials, Xray microscopy. In the medical literature described and widely discussed such issues with endoscopic studies related to earlystage cancer (or other) diseases, by using different types of external exposure to radiation, including laser. It is known that the most effective method of radiation exposure (at minimum injury to healthy cells) is the x-rays aimed directly (locally) to the affected area with not very high energies (and therefore, with comparatively small depth of penetration) and precisely controlled local dose.Until now, such methods had not been developed because of the lack of miniature x-ray sources. Listed in our articles data used to generate a focused pulsed X-rays (photons with energies of the order of 80-100 keV) metamaterials based on opal matrices show the reality of the creation of endoscopic devices using fiber-optic cables to the size input devices themselves to generate not more than 1-1.5 mm both in length and in diameter.Recently in Central Scientific Technology Institute "Technomash" a method has been developed (and patented) for generating pulsed X-ray radiation with a small angular divergence, which is based on a pulsed ruby laser with power density 0.25-2.0 GW/cm 2 interaction with opal matrix -an ordered structure of X-ray amorphous silica (SiO 2 ) nanospheres with diameters in the range of 200-350 nm [1][2][3][4]. Variations in the diameter of a single sample were not more than ± 3%). Voids between spheres were filled with the material with dielectric constant value (ε) more than 2.5. Filling factor was in the range of 30-85%. Due to the opal matrix structure as a densely packed lattice of SiO 2 nanospheres (Fig. 1), the samples are both photonic structures with a system of photonic band gaps. If the voids between spheres are filled with dielectric materials with large ε' or electrically (magnetically) active materials, such substances may be considered as metamaterials.Ruby laser pulse (λ=694.3 nm, τ=20 ns, E max =0.3 J) has been used as a source of excitation. Exciting light has been focused into the material by lenses with different focal lengths (50, 90, and 150 mm). The sample distance from focusing system and exciting light energy were also changed. It allowed us to vary the power density at the entrance of the sample and field distribution in microvoids inside the sample (Fig. 2). a) b) Fig. 1. a) Structure (SEM) of the volume opal matrix sample surface (ordered package of SiO 2 nanospheres). b) Tetrahedral and octahedral nanovoids (in accordance with a number of spheres, forming void), produced by SiO 2 nanospheres.