COLOUR PERCEPTION OF LED POINT LIGHT SOURCES IN SCOTOPIC VISION

2021 ◽  
Author(s):  
Riho Ogawa ◽  
Midori Tanaka ◽  
Takahiko Horiuchi
Keyword(s):  
Test Stimulus ◽  
Blackbody Radiation ◽  
Reference Stimulus ◽  
Light Sources ◽  
Small Field ◽  
Colour Perception ◽  
Scotopic Vision ◽  
Normal Individuals ◽  
Point Light

When stimuli are made sufficiently small, colour-normal individuals report a loss in hue perception, similar to tritanopia. This effect is referred to as small-field tritanopia. The interaction between small-field tritanopia and the rods working in scotopic vision has not been clarified. In this study, the problem is investigated by freely adjusting the hue, lightness, and saturation of the test stimulus to match the colour of the reference stimulus by observers. Three colours on the blackbody radiation trajectory with colour temperatures of 3500K, 5400K, and 11600K were used as reference colours. Each stimulus subtended a diameter of 6' and 10.8'. The 5400K and 11600K stimuli were distributed diagonally from the lower left to the upper right of each reference stimulus in the CIE 1976 u’v’ uniform chromaticity scale diagram. The distribution was similar to those of tritanopia. For the 3500K stimulus, the result did not show the influence of small-field tritanopia.

scholarly journals Optical Losses in Hybrid Microcavity Based in Porous Semiconductors and its Application as Optic Chemical Sensor

2019 ◽  
Vol 56 ◽  
pp. 158-167
Author(s):  
Claudia Antonio Hernández ◽  
Edith Osorio ◽  
Raúl Urteaga ◽  
Roberto Koropecki ◽  
José Alberto Alvarado ◽  
...  
Keyword(s):  
Chemical Sensor ◽  
Visible Region ◽  
Bragg Reflector ◽  
Resonant Peak ◽  
Light Sources ◽  
Optical Losses ◽  
Distributed Bragg Reflector ◽  
Nanoporous Anodic Alumina ◽  
Porous Semiconductors ◽  
Point Light

In this study the experimental and theoretical optical analysis of a hybrid microcavity (HM) based in porous silicon (PS) and nanoporous anodic alumina (NAA) are presented. The microcavity was centered in the visible region at 760 nm. Distributed Bragg reflector (DBR) was obtained using galvanostatic anodizing method and while NAA by the two-step anodization technique. From SEM micrographs the HM different regions are observed. HM optical characterization in the visible region was done, considering two different light sources, point and non-point respectively. These results reveal a decrease in the quality factor (Q) from 350 to 190 when the source is exchanged; this behavior has been mainly attributed to the light scattering at NAA. Furthermore, it was possible to study Q change, through transmittance simulation using the transfer matrix and Landau-Lifshitz-Looyenga theoretical methods. When a point light source is used, there are no optical losses making possible to sense 1% of analyte resulting in a 0.29 nm redshift of the resonant peak. According with these results we propose to apply the HM as chemical optic sensor.

Mitigation of even harmonics in the Fourier components of vertical illuminance around a reference point

2019 ◽  
Vol 52 (5) ◽  
pp. 675-691
Author(s):  
RA Mangkuto ◽  
B Paramita ◽  
SS Utami
Keyword(s):  
Sensitivity Analysis ◽  
Reference Point ◽  
Point Sources ◽  
Light Sources ◽  
Sensitivity Analysis Method ◽  
Genetic Algorithm Method ◽  
Components Analysis ◽  
Optimisation Methods ◽  
Point Light ◽  
Even Harmonics

The use of Fourier components analysis has been recently proposed by Lynes to describe harmonics in vertical illuminance at various azimuth angles around a reference point. In cases with multiple light sources, it has been argued that the removal of even harmonics in the resulting Fourier components may correspond with good lighting practice. This paper therefore aims to demonstrate optimisation methods to mitigate even harmonics in Fourier components of vertical illuminance around a reference point due to two and three point light sources, by adjusting maximum vertical illuminance and subtended angles between the sources using sensitivity analysis and genetic algorithms. The results suggest that the genetic algorithm method yields more precise optimum solutions compared with the sensitivity analysis method, particularly for scenes with three point sources. For two point sources, the smallest root mean square value of even harmonics is achieved when the vertical illuminance due to the second source is 0.92 (relative to the vertical illuminance due to the first source) and the subtended angle is 90°. For three point sources, the optimum vertical illuminance due to the second and third sources is respectively 0.81 and 0.78, whereas the optimum subtended angles for the second and third sources with respect to the first are 64.4° and 116.8°, respectively.

Near Field Photometric Stereo with Point Light Sources

2014 ◽  
Vol 7 (4) ◽  
pp. 2732-2770 ◽  
Author(s):  
Roberto Mecca ◽  
Aaron Wetzler ◽  
Alfred M. Bruckstein ◽  
Ron Kimmel
Keyword(s):  
Near Field ◽  
Photometric Stereo ◽  
Light Sources ◽  
Point Light
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