Search results for "Physics::Optics"

Photonic crystal intermediate reflector in micromorph tandem solar cells

2011

Experimental and numerical evidences are presented which show that the efficiency of silicon based tandem solar-cells can be increased by incorporating a three-dimensional photonic crystal as an intermediate reflector.

Gravity-Driven Infiltration and Subsidence Phenomena in Posidonia oceanica Residues

2019

A simplified infiltration model for highly permeable porous media was introduced, assuming the matric potential gradient as negligible compared to the gravitational gradient. This model enabled us to determine the delay time, i.e., the time that the water front takes (from the beginning of rainfall) to reach the bottom of the highly permeable layer. Posidonia oceanica (Linnaeus) Delile residues were used as a porous media, in order to study the infiltration process that provides salt leaching under natural rainfall when these residues are arranged in a storage area, before reusing. By using a laboratory rainfall simulator, delay times were measured to verify the applicability of the aforeme…

Coherent Amplification of the Short Optical Pulse in a Non-linear Birefringent Medium

2006

International audience; The propagation of the solitary waves in the resonant birefringent amplifier with linear losses is considered. The birefringent optical linear medium contains two-level atoms with the upper state degenerated over projection of angular moment. It is assumed that population of resonance levels of atoms is inverted. The steady state pulse of polarized radiation that is vectorial generalization of the known pi-pulse was analytically found. Numerical simulations demonstrate the formation dynamics solitary waves originated in birefringent amplifier.

Scaling symmetries and optimization of the refractive index profile in optical fibers

2019

The optical fiber refractive index profile has a significant role in the optical devices fabrication like fiber Bragg gratings (FBG) and acousto-optic devices and the way guided light interacts in the presence of external factors like strain, stress or even bends. The analysis of the fiber profile gets to be feasible throughout understanding the properties of the optical guided modes such as the effective index, group index, and the chromatic dispersion. Taking a broader look at previous publications that use standard commercial optical fibers, it becomes noticeable that the ideal core-cladding step index profile gives incompatible results when it comes to the experimental versus the simula…

LU FMOF optometrijas un redzes zinātnes nodaļas un Latvijas optometristu un optiķu asociācijas konferenču referātu tēzes

2020

Tēzes no LU 78.starptautiskās zinātniskās konferences Cilvēka fizioloģijas un uztveres sēdes un LU Optometrijas un redzes zinātnes nodaļas un LOOA kopīgās klīniski praktiskās konferences Rīgā, 2020.gada 14., 16. februārī

1981

Refractive indices and refractive index increments of the system polystyrene/trans-decalin were measured under pressures up to 500 bar and at temperatures between 20 and 60°C. The measurements were performed with a new, recently designed interferometer. The results demonstrate a sufficient agreement of the refractive index values measured at different temperatures and pressures with the equations of Eykman and Gladstone-Dale whereas the Lorenz-Lorentz equation indicates larger deviations. The experimental data of the refractive index increment follow none of the refractive index mixture rules. It is therefore recommended to determine refractive index increments at different pressures experi…

Improved superresolution in coherent optical systems.

2001

Objects that temporally vary slowly can be superresolved by the use of two synchronized moving masks such as pinholes or gratings. This approach to superresolution allows one to exceed Abbe’s limit of resolution. Moreover, under coherent illumination, superresolution requires a certain approximation based on the time averaging of intensity rather than of field distribution. When extensive digital postprocessing can be incorporated into the optical system, a detector array and some postprocessing algorithms can replace the grating that is responsible for information decoding. In this way, no approximation is needed and the synchronization that is necessary when two gratings are used is simpl…

Analytical characteristics, applications and perspectives in thermal lens spectrometry

1993

Abstract The following selected aspects of thermal lens spectrometry are briefly outlined: fundamentals, sensitivity and background noise, detection approaches, flowing samples, multi-wavelength experiments, thermal lens circular dichroism, associated colateral phenomena and physico-chemical applications and requirements of analytical procedures. The state-of-the-art and problems encountered are discussed.

Lau Effect And Binary Logic

1989

The Lau effect is applied to implement the whole set of binary logic operations optically. Our technique works with spatially incoherent light and does not require lenses or any other optical accessory.

Superresolving optical system with time multiplexing and computer decoding

2008

Objects that have slow temporal variations may be superresolved with two moving masks such as pinhole or grating. The first mask is responsible for encoding the input image, and the second one performs the decoding operation. This approach is efficient for exceeding the resolving capability beyond Abbe’s limit of resolution. However, the proposed setup requires two physical gratings that should move in a synchronized manner. We propose what is believed to be a novel configuration in which the second grating responsible for the information decoding is replaced with a detector array and some postprocessing digital procedures. In this way the synchronization problem that exists when two gratin…