scholarly journals Laser influence to biosystems

2015 ◽  
Vol 69 (4) ◽  
pp. 433-441 ◽  
Author(s):  
Sanja Jevtic ◽  
Milesa Sreckovic ◽  
Svetlana Pelemis ◽  
Ljubica Konstantinovic ◽  
Predrag Jovanic ◽  
...  
Keyword(s):  
Visible Region ◽  
Morphological Data ◽  
Visible Range ◽  
Time Intervals ◽  
Vegetative Period ◽  
Plant Seeds ◽  
Coefficient Of Reflection ◽  
Range Correlation ◽  
Recorded Data ◽  
Quantum Generator

In this paper a continous (cw) lasers in visible region were applied in order to study the influence of quantum generator to certain plants. The aim of such projects is to analyse biostimulation processes of living organizms which are linked to defined laser power density thresholds (exposition doses). The results of irradiation of corn and wheat seeds using He-Ne laser in the cw regime of 632.8nm, 50mW are presented and compared to results for other laser types. The dry and wet plant seeds were irradiated in defined time intervals and the germination period plant was monitored by days. Morphological data (stalk thickness, height, cob lenght) for chosen plants were monitored. From the recorded data, for the whole vegetative period, we performed appropriate statistical data processing. One part of experiments were the measurements of coefficient of reflection in visible range. Correlation estimations were calculated and discussed for our results. Main conclusion was that there were a significant increments in plant's height and also a cob lenght elongation for corn.

scholarly journals DIGITAL IMAGE ANALYSIS OF THE VISIBLE REGION THROUGH SIMULATION OF ROCK ART PAINTINGS

2016 ◽  
Author(s):  
Berta Carrión-Ruiz ◽  
Silvia Blanco-Pons ◽  
Jose Luis Lerma
Keyword(s):  
Rock Art ◽  
Visible Region ◽  
Visible Spectrum ◽  
Principal Component ◽  
Optical Filters ◽  
Visible Range ◽  
Redundant Data ◽  
The Difference ◽  
Entire Visible Spectrum ◽  
New Research

Non-destructive rock art recording techniques are getting special attention in the last years, opening new research lines in order to improve the level of documentation and understanding of our rich legacy. This paper applies the principal component analysis (PCA) technique in images that include wavelengths between 400-700 nm (visible  range). Our approach is focused on determining the difference provided by the image processing of the visible region through four spectral images versus an image that encompasses the entire visible spectrum. The images were taken by means of optical filters that take specific wavelengths and exclude parts of the spectrum. Simulation of rock art is prepared in laboratory. For this purpose, three different pigments were made simulating the material composition of rock art paintings. The advantages of studying the visible spectrum in separate images are analysed. In addition, PCA is applied to each of the images to reduce redundant data. Finally, PCA is applied to the image that contains the entire visible spectrum and is compared with previous results. Through the results of the four visible spectral images one can begin to draw conclusions about constituent painting materials without using decorrelation techniques.

scholarly journals Broadband plasmonic silver nanoflowers for high-performance random lasing covering visible region

Nanophotonics ◽  
2017 ◽  
Vol 6 (5) ◽  
pp. 1151-1160 ◽  
Author(s):  
Qing Chang ◽  
Xiaoyu Shi ◽  
Xuan Liu ◽  
Junhua Tong ◽  
Dahe Liu ◽  
...  
Keyword(s):  
Quality Factor ◽  
High Performance ◽  
Coupling Effect ◽  
Synthesis Method ◽  
Visible Region ◽  
High Quality Factor ◽  
Visible Range ◽  
Random Lasing ◽  
High Quality ◽  
Random Lasers

AbstractMulticolor random lasing has broad potential applications in the fields of imaging, sensing, and optoelectronics. Here, silver nanoflowers (Ag NF) with abundant nanogaps are fabricated by a rapid one-step solution-phase synthesis method and are first proposed as effective broadband plasmonic scatterers to achieve different color random lasing. With abundant nanogaps and spiky tips near the surface and the interparticle coupling effect, Ag NFs greatly enhance the local electromagnetic field and induce broadband plasmonic scattering spectra over the whole visible range. The extremely low working threshold and the high-quality factor for Ag NF-based random lasers are thus demonstrated as 0.24 MW cm−2 and 11,851, respectively. Further, coherent colorful random lasing covering the visible range is realized using the dye molecules oxazine (red), Coumarin 440 (blue), and Coumarin 153 (green), showing high-quality factor of more than 10,000. All these features show that Ag NF are highly efficient scatterers for high-performance coherent random lasing and colorful random lasers.

scholarly journals Boron-doped TiO2 (B-TiO2) Thin Films Grown Using Sol-Gel Spin Coating Method

2018 ◽  
pp. 1-17
Author(s):  
D. O. Samson ◽  
A. D. A. Buba
Keyword(s):  
Thin Films ◽  
Wavelength Range ◽  
Doping Concentration ◽  
Sol Gel ◽  
Visible Region ◽  
Boron Doping ◽  
Pure Tio2 ◽  
Visible Range ◽  
Ultraviolet Region ◽  
Tio2 Thin Films

In this study, the effect of modifying boron doping concentration on the optical properties, electrical properties and microstructural images of TiO2 thin films was investigated by the sol-gel technique by grinding TiO2 powder with a boron compound at a wavelength range of 250 nm to 850 nm. The SEM micro-images revealed the homogenous, continuous and nanocrystalline surface morphology: 10% is the tolerable amount of boron doping concentration into the TiO2 for achieving sphere-like nanostructures materials with low agglomeration. The XRD spectra of the B-TiO2 films showed anatase peaks of greater intensities when compared to the pure TiO2 film. All the films illustrate extinction coefficient in the visible region of solar spectra corresponding to the low absorption, and absorption peaks established in the ultraviolet region near 330nm with the optical transmittance varied from over 52 - 96% in the UV-Vis wavelength range. Diffuse reflectance absorption spectra analysis indicated that the incorporation of B into TiO2 material results in a substantial red shift and the absorption extends significantly into the visible range. The optical band gap energy values of the thin films were found to be 3.38, 3.35, 3.28, 3.26, and 3.36eV. This showed a low probability of raising the electron across the mobility gap with the photon energy in the visible region. The refractive index values varied between 1.891 and 1.922 depending on the percentage content of boron. Moreover, the imaginary part of the dielectric constant increase slowly, whereas the real part increases sharply and the optical conductivity was found to increase with the increase in boron addition.  

Theoretical analysis on the sensitivity to partial pressure of oxygen of the band gap shift in CdO thin films

2016 ◽  
Vol 30 (31) ◽  
pp. 1650371 ◽  
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Band Gap ◽  
Cadmium Oxide ◽  
Visible Region ◽  
Visible Range ◽  
Partial Pressure Of Oxygen ◽  
Sensitivity Functions ◽  
Suitable Parameter ◽  
Cdo Thin Films

With the aim of providing an analytical approach (not accurate numerical results), for the first time, the sensitivity to the partial pressure of oxygen of the shift in the energy band gap experienced by cadmium-oxide thin films is evaluated for the visible region by introducing a suitable parameter. The sensitivity to the above pressure of the spatial carrier density is determined and compared with the sensitivity relative to the band gap shift. The gradient of the CdO carrier concentration as a function of the partial pressure of oxygen appears in the expressions for the two above sensitivity functions but the goal of this paper is not computing numerically this gradient so only qualitative estimations are done. In relation to the above results, the kinetics relative to the formation of CdO thin films are investigated. In addition, the sensitivity to the pressure in question of the corresponding optical-absorption shift in the visible range is calculated.

EFFECT OF THICKNESS ON THE PROPERTIES OF In-DOPED ZnO THIN FILMS PREPARED BY RF MAGNETRON SPUTTERING

2011 ◽  
Vol 25 (07) ◽  
pp. 995-1003 ◽  
Author(s):  
L. P. PENG ◽  
L. FANG ◽  
X. F. YANG ◽  
Q. L. HUANG ◽  
F. WU ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Film Thickness ◽  
Visible Region ◽  
Hexagonal Wurtzite Structure ◽  
Rf Magnetron Sputtering ◽  
Transparent Electrode ◽  
Visible Range ◽  
Electrical And Optical Properties ◽  
Glass Substrates

In-doped zinc oxide ( ZnO:In ) thin films with thickness from 157 nm to 592 nm have been deposited on glass substrates by radio frequency (RF) magnetron sputtering. The effect of the film thickness on the structural, electrical and optical properties of ZnO:In thin films has been investigated. It is found that the films are hexagonal wurtzite structure with c-axis perpendicular to the substrate, and with increasing thickness, the crystallinity, the grains size and the conductivity of the films increases, but the strains along c-axis and the transmittance decrease. The decrease of the resistivity in a thicker film is attributed to the slight increase of the carrier concentration and the significant increase of Hall mobility. The transmittance of all the films is over 80% in the visible region (400–800 nm) and the band gap decrease with the increase of film thickness. The film with the thickness of around 303 nm has the resistivity of 6.07 × 10-3 Ω⋅ cm and the transmittance of 90% in the visible range. Based on the good conductivity and high transmittance, the ZnO:In films prepared by magnetron sputtering can be regarded as a potential transparent electrode.

Fast Scanning Hadamard Spectrophotometer

1992 ◽  
Vol 46 (12) ◽  
pp. 1822-1827 ◽  
Author(s):  
Ronei J. Poppi ◽  
Pedro A. M. Vazquez ◽  
Celio Pasquini
Keyword(s):  
Flow Injection ◽  
Flow Injection Analysis ◽  
Low Cost ◽  
Visible Range ◽  
Hadamard Transform ◽  
Absorbance Spectrum ◽  
Time Intervals ◽  
Time Resolved ◽  
Spinning Disk ◽  
Absorbance Data

A simple, low-cost, multiplexed Hadamard-type spectrophotometer based on a spinning disk containing 63 separated masks has been constructed to obtain spectral data in time intervals down to 50 ms. Each mask contains 63 resolution elements. Optical localization and identification of the masks were implemented in the disk to avoid misalignment problems. The control of the spectrophotometer and data acquisition was made by using a dedicated single-board microcomputer based on an 8085 CPU. The single board microcomputer sends the data, through an RS-232C interface, to an IBM-AT compatible microcomputer where the Hadamard transform is performed to recover and display the emission, transmittance, or absorbance spectrum. The instrument has been used in the visible range to obtain absorbance data for time-resolved flow injection analysis applications.

scholarly journals Carbon modified TiO2 photocatalysts for water purification

2009 ◽  
Vol 11 (2) ◽  
pp. 46-50 ◽  
Author(s):  
Antoni Morawski ◽  
Magdalena Janus ◽  
Beata Tryba ◽  
Masahiro Toyoda ◽  
Tomoki Tsumura ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Water Purification ◽  
Visible Region ◽  
Carbon Layer ◽  
Photocatalytic Decomposition ◽  
Visible Range ◽  
Tio2 Photocatalysts ◽  
Carbon Doped ◽  
Carbon Coated

Carbon modified TiO2 photocatalysts for water purification Carbon can form different structures with TiO2: carbon-doped TiO2, carbon coated TiO2 and composites of TiO2 and carbon. The presence of carbon layer on the surface of TiO2 as well as the presence of porous carbon in the composites with TiO2 can increase the concentration of organic pollutants on the surface of TiO2, facilitating the contact of the reactive species with the organic molecules. Carbon-doped TiO2 can extend the absorption of the light to the visible region by the narrowing of the band gap and makes the photocatalysts active under visible light irradiation. TiO2 loaded carbon can also work as a photocatalyst, on which the molecules are adsorbed in the pores of carbon and then they undergo the photocatalytic decomposition with UV irradiation. Enhanced photocatalytic activity for the destruction of some organic compounds in water was noticed on the carbon coated TiO2 and TiO2 loaded activated carbon, mostly because of the adsorptive role of carbon. However, in carbon-doped TiO2, the role of carbon is somewhat different, the replacement of carbon atom with Ti or oxygen and formation of oxygen vacancies are responsible for extending its photocatalytic activity towards the visible range.

scholarly journals High-Order Resonant Peaks and Polarization Dependence of Microphotoluminescence in Whispering-Gallery Mode ZnO Microrod Cavity

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Jiatian Guo ◽  
Huihui Wei ◽  
Jingyi Song ◽  
Yunhui Guo ◽  
Xiaobo Yuan
Keyword(s):  
Visible Region ◽  
Whispering Gallery Mode ◽  
High Order ◽  
Polarization Dependence ◽  
Optical Methods ◽  
Visible Range ◽  
Whispering Gallery ◽  
High Order Resonance ◽  
Growth Method ◽  
Pl Spectrum

High order phenomena in the visible range and with polarization dependence in the ultraviolet (UV) region of the microphotoluminescence (micro-PL) spectrum in whispering-gallery mode (WGM) ZnO microrod cavity have been thoroughly studied at room temperature. WGM ZnO microrod cavity with good crystallinity is produced by the CVD growth method, and the ZnO microrod structures are characterized by structural and optical methods. Through the micro-PL spectrum measurement of the ZnO microrod, it is found that high-order resonance peaks appeared in the visible region. The different polarization conditions can be adjusted by rotating the angles of the polarizer, and it is proved that the micro-PL spectrum has strong polarization-dependent behavior in the UV region. Our results imply broad application potentials in the study of ZnO microrod-based photonic cavity devices.

scholarly journals SYNTHESIS AND INVESTIGATION SOME PROPERTIES OF WO3 ELECTROCHROMIC THIN FILMS

2018 ◽  
Vol 54 (1A) ◽  
pp. 112
Author(s):  
Nguyen Duy Thien
Keyword(s):  
Thin Films ◽  
Applied Voltage ◽  
Visible Region ◽  
Visible Range ◽  
Raman Scattering Spectroscopy ◽  
X Ray ◽  
Glass Substrates ◽  
Substrate Adhesion ◽  
Vis Spectroscopy ◽  
Wo3 Thin Films

The study of electrochromic thin films, which are transparent in the visible range, is significantly important in producing smart doors production and saving energy. This paper reports the results of preparing WO3 thin films on glass substrates and ITO substrates by thermal vacuum evaporation method. The influence of annealing temperature on the properties of thin films was investigated by X-ray diffraction, Raman scattering spectroscopy, X-ray energy dispersive spectroscopy, Atomic force microscopy and absorption and transmittance UV–vis spectroscopy. The results show that WO3 thin films have a high transmittance of about 90% in the visible wavelength from 400 to 900 nm, good substrate adhesion. The WO3 thin films were crystallized at 400 oC and the crystallization of thin films on the ITO substrate better than glass substrate. Electrochromic characteristics of WO3 thin films were investigated by Autolab electrochemical system. The results show the transmittance of WO3 thin film was reduced to around 12 % in visible region when increasing the applied voltage from - 0.1 V to - 0.7 V. The transmittance of the film was completely recovered by using an applied voltage of 2 V.

Perfect Selective Metamaterial Absorber With Thin-Film of GaAs Layer In The Visible Region For Solar Cell Applications

2021 ◽  
Author(s):  
Raj Kumar ◽  
Bipin K Singh ◽  
Rajesh K Tiwari ◽  
Praveen C Pandey
Keyword(s):  
Structural Parameters ◽  
Short Circuit ◽  
Effective Permittivity ◽  
Visible Region ◽  
Special Kind ◽  
Short Circuit Current ◽  
Gaas Layer ◽  
Visible Range ◽  
Perfect Absorber ◽  
Perfect Absorption

Abstract In this paper, we have presented a new design of a metamaterial perfect absorber (MPA) consisting of three layers of metal-dielectric-metal in which the top layer is considered of special kind square patches at different places in a unit cell. This MPA exhibits wideband, wide-angle, and polarization-independent absorption performance in the visible region. This structure originates the plasmonic resonance which is responsible for the perfect absorption in the optical region. Under a specific condition, this simulated absorber structure exhibits an extremely high broadband absorption between 591.54 nm to 704.40 nm wavelength range with near-unity absorption, and a single peak observed at 385.33 nm with absorption 94.16%. We extracted the impedance of the absorber and matched it with free space, and also demonstrated the effective permittivity and permeability. Moreover, the parametric study of the resonators, dielectric layer, and multi-band topology has also been investigated. The polarization-insensitive-based metamaterial may be utilized to improve the efficiency of different devices in the visible range. Furthermore, we have calculated the absorption of the proposed MPA under the solar radiation (AM1.5) for different structural parameters. The proposed absorber greatly enhances the conversion efficiency which is highly useful for solar cells. We also determined the short circuit current density of this absorber for different thicknesses of the GaAs layer. Al metal patches at meta-surface provide nearly similar performance in comparison with other costly metals. Therefore, the proposed structure with cheaper Al metal may be used for different devices as the perfect absorber.

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