Absorptance measurement of nonlinear crystals by calorimetric method at 1064 and 532 nm

2002 ◽  
Author(s):  
Ona Balachninaite ◽  
M. Barkauskas ◽  
Robert C. Eckardt ◽  
Rimantas Grigonis ◽  
M. Maciulevicius ◽  
...  
Keyword(s):  
Calorimetric Method ◽  
Nonlinear Crystals ◽  
532 Nm

Prospects of development of the reference base of the Russian Federation in the field of length measurements

2020 ◽  
pp. 3-5
Author(s):  
Y. G. Zakharenko ◽  
N. A. Kononova ◽  
V. L. Fedorin ◽  
Z. V. Fomkina ◽  
K. V. Chekirda
Keyword(s):  
High Precision ◽  
Russian Federation ◽  
Reference Base ◽  
Length Measurements ◽  
Laser Sources ◽  
The Russian Federation ◽  
Unit Of Length ◽  
Further Development ◽  
532 Nm

The results of the work to create a complex of high-precision hardware for the unit of length reproduction and transferring carried out at “D. I. Mendeleyev Institute for Metrology (VNIIM)” are represented. This complex will serve as the basis for the further development of the reference base of the Russian Federation in the field of length measurements and will allow reproduction of the unit of length at two wavelengths of 633 nm and 532 nm, as well as measurements of the wavelength of laser sources in vacuum in the range from 500 to 1050 nm.

Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

2020 ◽  
pp. 139-143
Keyword(s):  
Absorption Coefficient ◽  
Water Solution ◽  
Optical Limiting ◽  
Refraction Index ◽  
Laser Wavelength ◽  
Solid State Laser ◽  
Natural Dyes ◽  
Linear And Nonlinear ◽  
532 Nm ◽  
Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

The efficacy of using 532 nm and 577 nm lasers in diabetic retinopathy

2018 ◽  
pp. 20-22
Author(s):  
D.A. Goydin ◽  
◽  
S.V. Shutova ◽  
A.P. Goydin ◽  
O.L. Fabrikantov ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
532 Nm

Ultrastructural changes of the rabbits retina after threshold laser radiation with a wavelength of 532 nm, 577nm and 810 nm

2014 ◽  
Vol 52 (6) ◽  
pp. 89-94
Author(s):  
N. Dumbrova ◽  
◽  
N. Molchanyuk ◽  
T. Romanova ◽  
N. Gavronskaya ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Ultrastructural Changes ◽  
532 Nm

scholarly journals Classification of Tree Species as Well as Standing Dead Trees Using Triple Wavelength ALS in a Temperate Forest

2019 ◽  
Vol 11 (22) ◽  
pp. 2614 ◽  
Author(s):  
Nina Amiri ◽  
Peter Krzystek ◽  
Marco Heurich ◽  
Andrew Skidmore
Keyword(s):  
Tree Species ◽  
Feature Selection Method ◽  
Silver Fir ◽  
Maximum Point ◽  
Individual Tree ◽  
Dead Trees ◽  
Multi Wavelength ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
532 Nm

Knowledge about forest structures, particularly of deadwood, is fundamental for understanding, protecting, and conserving forest biodiversity. While individual tree-based approaches using single wavelength airborne laserscanning (ALS) can successfully distinguish broadleaf and coniferous trees, they still perform multiple tree species classifications with limited accuracy. Moreover, the mapping of standing dead trees is becoming increasingly important for damage calculation after pest infestation or biodiversity assessment. Recent advances in sensor technology have led to the development of new ALS systems that provide up to three different wavelengths. In this study, we present a novel method which classifies three tree species (Norway spruce, European beech, Silver fir), and dead spruce trees with crowns using full waveform ALS data acquired from three different sensors (wavelengths 532 nm, 1064 nm, 1550 nm). The ALS data were acquired in the Bavarian Forest National Park (Germany) under leaf-on conditions with a maximum point density of 200 points/m 2 . To avoid overfitting of the classifier and to find the most prominent features, we embed a forward feature selection method. We tested our classification procedure using 20 sample plots with 586 measured reference trees. Using single wavelength datasets, the highest accuracy achieved was 74% (wavelength = 1064 nm), followed by 69% (wavelength = 1550 nm) and 65% (wavelength = 532 nm). An improvement of 8–17% over single wavelength datasets was achieved when the multi wavelength data were used. Overall, the contribution of the waveform-based features to the classification accuracy was higher than that of the geometric features by approximately 10%. Our results show that the features derived from a multi wavelength ALS point cloud significantly improve the detailed mapping of tree species and standing dead trees.

Recovery of wave-mixing conversion efficiency in weakly scattering nonlinear crystals

2018 ◽  
Vol 43 (15) ◽  
pp. 3734 ◽  
Author(s):  
Zhuo Wang ◽  
Yanqi Qiao ◽  
Shuo Yan ◽  
Haoying Wu ◽  
Yuanlin Zheng ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Wave Mixing ◽  
Nonlinear Crystals

scholarly journals Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

2021 ◽  
Vol 13 (14) ◽  
pp. 2769
Author(s):  
Xiaomei Lu ◽  
Yongxiang Hu ◽  
Ali Omar ◽  
Rosemary Baize ◽  
Mark Vaughan ◽  
...  
Keyword(s):  
Polarization Plane ◽  
Optical Power ◽  
Satellite Observations ◽  
Global Ocean ◽  
Reference Plane ◽  
Orthogonal Polarization ◽  
True Value ◽  
Before And After ◽  
Oriented Parallel ◽  
532 Nm

Recent studies indicate that the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provides valuable information about ocean phytoplankton distributions. CALIOP’s attenuated backscatter coefficients, measured at 532 nm in receiver channels oriented parallel and perpendicular to the laser’s linear polarization plane, are significantly improved in the Version 4 data product. However, due to non-ideal instrument effects, a small fraction of the backscattered optical power polarized parallel to the receiver polarization reference plane is misdirected into the perpendicular channel, and vice versa. This effect, known as polarization crosstalk, typically causes the measured perpendicular signal to be higher than its true value and the measured parallel signal to be lower than its true value. Therefore, the ocean optical properties derived directly from CALIOP’s measured signals will be biased if the polarization crosstalk effect is not taken into account. This paper presents methods that can be used to estimate the CALIOP crosstalk effects from on-orbit measurements. The global ocean depolarization ratios calculated both before and after removing the crosstalk effects are compared. Using CALIOP crosstalk-corrected signals is highly recommended for all ocean subsurface studies.

scholarly journals Amplification by stimulated emission of nitrogen-vacancy centres in a diamond-loaded fibre cavity

Nanophotonics ◽  
2020 ◽  
Vol 9 (15) ◽  
pp. 4505-4518
Author(s):  
Sarath Raman Nair ◽  
Lachlan J. Rogers ◽  
Xavier Vidal ◽  
Reece P. Roberts ◽  
Hiroshi Abe ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gain Medium ◽  
Stimulated Emission ◽  
Nitrogen Vacancy ◽  
Qualitative Model ◽  
Seed Laser ◽  
Laser Threshold ◽  
Cavity System ◽  
Emission Changes ◽  
532 Nm

AbstractLaser threshold magnetometry using the negatively charged nitrogen-vacancy (NV−) centre in diamond as a gain medium has been proposed as a technique to dramatically enhance the sensitivity of room-temperature magnetometry. We experimentally explore a diamond-loaded open tunable fibre-cavity system as a potential contender for the realisation of lasing with NV− centres. We observe amplification of the transmission of a cavity-resonant seed laser at 721 nm when the cavity is pumped at 532 nm and attribute this to stimulated emission. Changes in the intensity of spontaneously emitted photons accompany the amplification, and a qualitative model including stimulated emission and ionisation dynamics of the NV− centre captures the dynamics in the experiment very well. These results highlight important considerations in the realisation of an NV− laser in diamond.

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