نتایج جستجو برای: optical reflectance
تعداد نتایج: 282209 فیلتر نتایج به سال:
Recently developed optical techniques provide quantitative structural measurements of the retinal nerve fiber layer (RNFL). A complete interpretation of these measurements requires understanding of the optical properties of the RNFL. This paper gives a review of the polarization properties and relevant anatomy of the ocular tissues, followed by a thorough discussion of the optical properties of...
The total biomass of a tall fescue (Festuca arundinacea var. Fletcher) pasture was assessed by using a vehicle mounted light detection and ranging (LiDAR) unit to derive canopy height and an active optical reflectance sensor to determine the spectro-optical reflectance index, normalized difference vegetation index (NDVI). In a random plot design, measurements of NDVI and pasture height were com...
We applied hyperspectral imaging to measure spatially-resolved diffuse reflectance spectra in the visible range and an iterative inversion method based on forward Monte Carlo modeling to quantify optical properties of two-layered tissue models. We validated the inversion method using spectra experimentally measured from liquid tissue mimicking phantoms with known optical properties. Results of ...
Mapping pigmentation in human skin is expected to give useful information in reproducing and diagnosing various skin colors. In this research, maps of melanin, oxyhemoglobin and deoxy-hemoglobin in skin are estimated from multi-visible-spectral image by using an inverse optical scattering technique. In the inverse optical scattering technique, first of all, a forward model of optical scattering...
To detect small-scale changes in tissue with optical techniques, small sampling volumes and, therefore, short source–detector separations are required. In this case, reflectance measurements are not adequately described by the diffusion approximation. Previous studies related subdiffusive reflectance to ? or ? , which parameterize the phase function. Recently, it was demonstrated that ? predict...
Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and do not require spectral reference readings. Besides measuring red (590-670 nm) and near-infrared ...
We have investigated a method for solving the inverse problem of determining the optical properties of a two-layer turbid model. The method is based on deducing the optical properties (OPs) of the top layer from the absolute spatially resolved reflectance that results from photon migration within only the top layer by use of a multivariate calibration model. Then the OPs of the bottom layer are...
An ideal black material absorbs light perfectly at all angles and over all wavelengths. Here, we show that low-density vertically aligned carbon nanotube arrays can be engineered to have an extremely low index of refraction, as predicted recently by theory [Garcia-Vidal, F. J.; Pitarke, J. M.; Pendry, J. B. Phys. Rev. Lett. 1997, 78, 4289-4292] and, combined with the nanoscale surface roughness...
In this work, the reflectance, optical absorption, and band gap have been determined for CdTe thin films grown on planar and microstructured substrates. The treated surface was prepared by laser ablation of a silicon wafer, forming holes in a periodic arrangement. Thin films were grown by pulsed laser ablation on silicon samples kept at 200 °C inside a vacuum chamber. The presence of CdTe was v...
PURPOSE To compensate for reflectance variation when quantifying vessel density by optical coherence tomography angiography (OCTA). METHODS Healthy participants received 6×6-mm macular and 4.5×4.5-mm optic nerve head (ONH) angiography scans on a 70-kHz spectral-domain optical coherence tomography system. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to comp...
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