scholarly journals Adjustable light source for low light level with nearly constant correlated color temperature

2022 ◽  
Vol 2149 (1) ◽  
pp. 012016
Author(s):  
Z F Wu ◽  
L Li ◽  
C H Dai ◽  
Y F Wang ◽  
Q T Cheng ◽  
...  
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Light Level ◽  
Color Temperature ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Spectral Difference ◽  
Low Light ◽  
Light Levels ◽  
Variable Aperture

Abstract Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

scholarly journals Interactive effects of temperature and light on reattachment success in the brown alga Fucus radicans

2019 ◽  
Vol 62 (1) ◽  
pp. 43-50
Author(s):  
Ellen Schagerström ◽  
Tiina Salo
Keyword(s):  
High Temperature ◽  
Water Temperature ◽  
Asexual Reproduction ◽  
Net Primary Production ◽  
Light Level ◽  
Interactive Effects ◽  
Low Light ◽  
Dispersal Capacity ◽  
Light Levels ◽  
The Baltic

Abstract Fucus radicans is an endemic habitat-forming brown macroalga in the Baltic Sea that commonly complements its sexual reproduction with asexual reproduction. Asexual reproduction in F. radicans takes place through formation of adventitious branches (hereafter fragments), but the exact mechanisms behind it remain unknown. We assessed experimentally the importance of two environmental factors determining the re-attachment success of F. radicans fragments. By combining different light conditions (daylength and irradiance; high or low light) and water temperature (+14°C and +4°C), we mimicked ambient light and temperature conditions of winter, spring/autumn and summer for F. radicans. Fragments were able to re-attach in all tested conditions. Temperature and light had an interactive impact on re-attachment: the combination of high temperature and high light level resulted in the highest re-attachment success, while light level had no effects on re-attachment success in cooler water temperature and the re-attachment success in high temperature under low light levels was very low. The results suggest that rhizoid formation, and thus re-attachment success, may depend on the net primary production (metabolic balance) of the fragment. However, whether the re-attachment and asexual reproduction success simply depends on photosynthetic capacity warrants further mechanistic studies. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the dispersal capacity of this foundation species.

scholarly journals Impact of different standard lighting sources on red jadeite and color quality grading

2019 ◽  
Vol 23 (4) ◽  
pp. 371-378
Author(s):  
Xin Pan ◽  
Ying Guo ◽  
Ziyuan Liu ◽  
Zikai Zhang ◽  
Yuxiang Shi
Keyword(s):  
Light Source ◽  
Color Space ◽  
Sample Surface ◽  
Color Temperature ◽  
Integrating Sphere ◽  
Light Sources ◽  
Light Spectrum ◽  
Fisher Discriminant Analysis ◽  
Fisher Discriminant ◽  
Quality Grading

The purpose of this paper is to investigate the standard light source for grading and displaying the color of red jadeite and to classify the color. With Raman spectrometer, ultraviolet-visible spectrophotometer and X-ray fluorescence spectrometer, the results show that, the Fe 3+ is the main chromogenic mineral of red jadeite, which negatively correlates with the tonal angle, while the color of red jadeite has a positive correlation with the hematite content. The color of 120 red jadeite samples was examined by collecting the reflective signaled from the sample surface using an integrating sphere with the portable X-Rite SP62 spectrophotometer based on CIE 1976 L*a*b* uniform color space. The color parameters of jadeite samples under D65, A and CWF standard light sources were analyzed. The light spectrum of D65 light source is continuous, relatively smoothed with high color temperature, which makes the sample color close to that under the natural light and can be used as the best evaluation light source. A light source contributes to improve the red tone of jadeite, which is the best light source for commercial display of red jadeite. CWF light source can be used as the auxiliary lighting for color evaluation. The color of red jadeite is divided into five levels from best to worst using K-Means cluster analysis and Fisher discriminant analysis under D65 light source: Fancy Vivid, Fancy Deep, Fancy Intense, Fancy dark and Fancy.

An Evaluative Study of Three Photographic Focusing Screens under Two Levels of Illumination

1980 ◽  
Vol 9 (1) ◽  
pp. 37-44
Author(s):  
John B. Bunch
Keyword(s):  
Light Level ◽  
Illumination Level ◽  
Low Light ◽  
Evaluative Study ◽  
Light Levels ◽  
High Illumination ◽  
Significant Difference ◽  
Low Illumination ◽  
Post Hoc

The purpose of this experiment was to evaluate the ability of photography students to focus a camera accurately under two levels of illumination (high/low) with three types of focusing screens (plain groundglass, split-image and microprism). The participants were required to focus each screen three times under each light level; scores were focus errors in feet. A 2 × 3 MANOVA design was used, and post hoc comparisons were made for plain vs. split-image, plain vs. microprism, and plain vs. microprism and split-image combined. There was significantly less focus error (p < .05) under the low illumination level, but no significant difference between screen types across both light levels. The screen type X light level interaction was much higher than the p .05 required in this study. Plain groundglass produced the least overall error; microprism yielded the least error under low illumination and the highest error under high illumination; and split-image was the most accurate under high illumination and the least accurate for the low light level condition.

scholarly journals Design and test of in-site radiometric calibration reference light source for spaceborne low light level remote sensors

2020 ◽  
Vol 41 (1) ◽  
pp. 140-144
Author(s):  
GAN Tao ◽  
◽  
◽  
YUAN Yinlin ◽  
ZHAI Wenchao ◽  
...  
Keyword(s):  
Light Source ◽  
Light Level ◽  
Radiometric Calibration ◽  
Low Light ◽  
Remote Sensors

SCUBA diver-operated low-light-level video system for use in underwater research and survey

1987 ◽  
Vol 67 (2) ◽  
pp. 299-306 ◽  
Author(s):  
G. W. Potts ◽  
J. W. Wood ◽  
J. M. Edwards
Keyword(s):  
High Resolution ◽  
Power Supply ◽  
Light Level ◽  
Natural Light ◽  
Scuba Diver ◽  
Ambient Light ◽  
Low Light ◽  
Marine Research ◽  
Light Levels ◽  
External Power

Television cameras and video equipment are well established as tools in many areas of marine research and have been reviewed by Barnes (1963), Myrberg (1973), Harris (1980), and Holme (1984, 1985). The TV camera is usually mounted on a remote sledge (Machan & Fedra, 1975; Holme & Barrett, 1977) or submersible, often with arrays of lights, and lacks the manoeuvrability that is necessary for many types of detailed survey and behavioural recording. Commercial and industrial uses also demand high-resolution equipment that is often contained in bulky underwater cases capable of operating at great depths and well below that possible by the conventional SCUBA diver. It is not unusual for the equipment to be used in conjunction with external lighting units where natural light levels are too low for the use of ambient light, and is dependent on an external power supply normally situated in the surface support vessel or within a submersible (Sisman, 1982).

Response to White Light Emitting Diode Aviation Signal Lights Varying in Correlated Color Temperature

2019 ◽  
Vol 2673 (3) ◽  
pp. 667-675 ◽  
Author(s):  
John D. Bullough ◽  
Yi-wei Liu
Keyword(s):  
Light Emitting Diode ◽  
Color Temperature ◽  
Light Sources ◽  
White Led ◽  
Low Light ◽  
Light Emitting ◽  
Light Levels ◽  
Relative Brightness ◽  
Discomfort Glare ◽  
Source Spectra

Airfield lighting for runways and taxiways is currently undergoing a transition from filament-based incandescent sources to light emitting diodes (LEDs). Although models to assess the relative brightness, discomfort glare, and peripheral detectability of signal lights such as those used for aviation exist, their applicability to white LED airfield lighting has not been verified independently. A series of three experiments was conducted to compare white LED sources, having correlated color temperatures of 2,700 K and 5,900 K, in terms of their relative brightness, discomfort glare, and peripheral detectability. The perceived brightness and discomfort glare from the light sources closely matched predictions from the published models, demonstrating the usefulness of these models at characterizing these responses in airfield lighting. In the case of peripheral detectability, there was little to no difference in how quickly the two LEDs were perceived at low light levels, suggesting that there is no need to consider spectral differences between light source spectra for this response when the intensities are similar to those used in the present study.

Motivation and approach to creating true color temperature low light level V-NIR source

2010 ◽  
Author(s):  
Stephen D. Scopatz ◽  
Jason A. Mazzetta ◽  
Fred A. Ennerson
Keyword(s):  
Light Level ◽  
Color Temperature ◽  
Low Light ◽  
True Color

scholarly journals Low light levels increase avoidance behaviour of diurnal fish species: Implications for road culverts

2020 ◽  
Author(s):  
John K. Keep ◽  
Jabin R. Watson ◽  
Rebecca L. Cramp ◽  
Matthew J. Jones ◽  
Matthew A. Gordos ◽  
...  
Keyword(s):  
Fish Species ◽  
Activity Patterns ◽  
Light Level ◽  
Fish Passage ◽  
Diel Activity ◽  
Low Light ◽  
Light Levels ◽  
Diel Activity Patterns ◽  
Australian Fish ◽  
Diurnal Species

AbstractInadequately designed culverts are known to pose hydraulic barriers to fish passage, but they may also be behavioural barriers if they adversely affect light levels within them. To test this, we performed a choice experiment and quantified the amount of time individuals of four Australian fish species spent in darkened and illuminated areas of an experimental swimming fume. Behavioural responses were reflective of the species’ diel activity patterns; diurnal species preferred illuminated regions, while nocturnal species preferred the darkened region. We then determined a threshold light level of only ~100-200 lux (c.f. midday sunlight ~100,000 lux) was required to overcome the behavioural barrier in ~ 70% of the diurnal fish tested. Placing these threshold values into field context, 100% of culverts sampled recorded inadequate light levels. Attention is required to better understand the impacts of low light levels in culverts on fish passage and to prioritise restoration.

scholarly journals Effects of Light, N and Defoliation on Biomass Allocation in Poa annua

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1783
Author(s):  
Louis John Irving ◽  
Sayuki Mori
Keyword(s):  
Biomass Allocation ◽  
Light Level ◽  
Poa Annua ◽  
Root Mass ◽  
Light Conditions ◽  
Low Light ◽  
Light Levels ◽  
Below Ground ◽  
Shoot Mass

Plants allocate biomass to above- and below-ground organs in response to environmental conditions. While the broad patterns are well-understood, the mechanisms by which plants allocate new growth remain unclear. Modeling approaches to biomass allocation broadly split into functional equilibrium type models and more mechanistically based transport resistance type models. We grew Poa annua plants in split root boxes under high and low light levels, high and low N supplies, with N supplied equally or unequally. Our data suggest that light level had the strongest effect on root mass, with N level being more important in controlling shoot mass. Allocation of growth within the root system was compatible with phloem partitioning models. The root mass fraction was affected by both light and N levels, although within light levels the changes were primarily due to changes in shoot growth, with root mass remaining relatively invariant. Under low light conditions, plants exhibited increased specific leaf area, presumably to compensate for low light levels. In a follow-up experiment, we showed that differential root growth could be suppressed by defoliation under low light conditions. Our data were more compatible with transport resistance type models.

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