Tin oxide (SnO2)nanoparticles were synthesized by co-precipitation method and the synthesized nanoparticles were annealed at different temperatures for characterization. The powders were investigated with X-ray diffraction, scanning electron microscopy and optical spectroscopy. The structural characterization was carried out by X-ray diffraction which confirms the crystalline nature ...

The polarised absorption coefficient of ZnSiP? near the fundamental absorption edge has been studied. Three singularities were found for E l c which are attributed to pseudodirect transitions. The absorption for El/ c is mainly due to indirect transitions. A theoretical curve was fitted to the experimental results with the aid of the relative theoretical intensities for pseudodirect transitions...

In this paper, after a brief overview on laser warning system (LWS), a new structure for an optical array that is used in its optical subsystem is introduced. According to the laser threats’ wavelengths (0.5 – 1.6 µm) and our desirable field of view (FOV), we used 6 lenses for gathering the incident radiation and then optimized the optical array. Lenses’ radius, their se...

Background: Similar to the thermoluminescence (TL) spectra, the optical parameters variations can also be used in TL crystals for dosimetry purposes. These optical parameters can include absorption, transmission and reflection coefficients. Materials and Methods: Single crystals of KBr and KCl which have been used in this research were grown from laboratory grade extra pure precursor p...

We have made HI 21cm-line absorption measurements using the GMRT towards 15 directions in the Galaxy which are known to have high random velocity clouds as seen in the optical absorption lines of CaII and NaI. For the first time, in 6 out of these 15 directions we detect HI absorption features corresponding to the high random velocity optical absorption lines. The mean optical depth of these de...

Metalloporphyrins are promising materials for optical limiting possessing strong nonlinear absorptio~ and high third order-optical nonlinearitiescombined with ultrafast response time in the picosecond and femtosecond time scales. Structural modifications like heavy atom effect and introduction of donor-acceptor groups are known to vary the excited state properties in these molecules. We discuss...

Anisotropic optical absorption properties of single-walled carbon nanotubes (SWNTs) are determined from a vertically aligned SWNT film for 0.5-6 eV. Absorption peaks at 4.5 and 5.25 eV are found to exhibit remarkable polarization dependence and have relevance to optical properties of graphite. A method for determining a nematic order parameter for an aligned SWNT film based on the collinear abs...