A new concept is proposed for digital hologram production along with the relevant techniques developed in our laboratory. The main idea of the concept is to maximally separate the calculation of hologram from its optical recording on the light-sensitive media. A special file format containing information on each holographic pixel is created at the stage of calculation. The file is a device-independent by structure, and can be employed for recording a hologram using any of the existing techniques (dot-matrix, optical matrix lithography, e-beam lithography). An optical lithography device is applied to calculate the images for a spatial light modulator at the stage of hologram recording in accordance with the data from the file and in conformity with the hardware features of the device. The proposed method was tested and successfully used to record security holograms. For commercial use a software package and an optical recording system have been developed.
The article discusses the use of computer-generated holograms (CGHs) for the application as one of the security features in the relief-phase protective holograms. An improved method of calculating CGHs is presented, based on ray-tracing approach in the case of interference of parallel rays.
Software is developed for the calculation of multilevel phase CGHs and their integration in the application of security holograms. Topology of calculated computer-generated phase holograms was recorded on the photoresist by the optical greyscale lithography. Parameters of the recorded microstructures were investigated with the help of the atomic-force microscopy (AFM) and scanning electron microscopy (SEM) methods. The results of the research have shown highly protective properties of the security elements based on CGH microstructures. In our opinion, a wide use of CGHs is very promising in the structure of complex security holograms for increasing the level of protection against counterfeit.
Physics Holographic Recording Device Based on LCoS Spatial Light Modulator
A PC-controlled holographic recording device has been developed in which a LC-R-2500 Spatial Light Modulator (SLM) based on reflective Liquid Crystal on Silicone (LCoS) display was used. The device allows the amplitude and phase modu-lation of coherent light wave fronts. In the optical scheme, a DPSS (Diode Pumped Solid State) laser with nanosecond pulse duration and wavelength 532 nm was applied. The holographic recording was made and tested in the amplitude and phase wave front modulation modes on a chalcogenide semiconductor photoresist As40S15S45. The experimental results are presented.
Principles of Creation and Reconstruction of Dot-Matrix Holograms
A method for calculation of dot-matrix holograms is presented, whose distinction from other methods is simplicity of the formulas for the parameters of each pixel element in a hologram. At the Innovation Spectroscopy Center of DU a device for recording dot-matrix holograms has been designed, with a program using the pro-posed method for their calculation. Holograms 50x50 mm in size well corresponding to the initial graphic design were obtained.
ELECTRIC CONDUCTIVITY OF Sb/Se THIN FILM MICRO-SCALE STRUCTURES
Research into the phase change transition (PCT) from amorphous to crystalline state in chalcogenide glass semiconductors is often more associated with large-scale samples. The authors present a micro-scale structural model of the Sb/Se thin films. They have also extended the investigations of photo- and thermo-stimulated inter-diffusion and PCT effects between two adjacent layers. The results show that the optical and electrical characteristics of such a film change simultaneously. It has been found that the electric conductivity of the films increases 3 times during a PCT process.
Well-structured ZnO nanotubes are obtained by a self-selective etching method with lowering temperatures of growth during the hydrothermal process.
The structural and optical properties of the obtained nanostructures are investigated by various conventional methods.
The goal of the research is to compare the efficiency of ZnO nanotubes to that of ZnO nanorods during lead adsorption process from aqueous solution and demonstrate that hollow nanostructures are more effective than solid nanostructures of the same morphology due to their larger effective surface.
Both nanotubes and nanorods are obtained under similar growth conditions: neither growth solution composition, nor concentration is changed. ZnO morphology is switched only by changing temperature during the growth process.
The measurements are carried out to assess the efficiency of the adsorption per unit weight of ZnO nanorod and nanotube capacity of static adsorption.
Selective Wet-Etching of Amorphous/Crystallized Sb-Se Thin Films
The paper is focused on the development of an in situ real-time method for studying the process of wet chemical etching of thin films. The results of studies demonstrate the adequate etching selectivity for all thin film SbxSe100-x (x = 0, 20, 40, 50, 100) compositions under consideration. Different etching rates for the as-deposited and laser exposed areas were found to depend on the sample composition. The highest achieved etching rate was 1.8 nm/s for Sb40Se60 samples.
The nanostructured ZnO thin films were successfully synthesized by rapid thermal oxidation of metallic zinc films without catalysts or additives. On the surface of thin films the formation of ZnO nanowires was observed. In the work, the optical and electrical parameters and photoresponses of the obtained ZnO thin films were investigated. Nanostructured thin films of the type have a promising potential for the use in optoelectronics, sensor technique and biomedical sciences
Mass-produced printed circuit board (PCB) electrodes were used as electrochemical cells to detect the widely-used herbicide glyphosate. Square wave voltammetry (SWV) was used to determine the presence of glyphosate in aqueous Cu(NO3)2 solution. Optimal measurement conditions for the detection of glyphosate with PCB electrodes were found. It was determined that glyphosate was able to soak into the growing plants from the substrate. Glyphosate-contaminated plant juice was distinguished from control samples using the PCB electrode. Glyphosate-contaminated plants were found to have DNA mutations.