scholarly journals Comparisons of Scotopic/Photopic Ratios Using 2- and 10-Degree Spectral Sensitivity Curves

2019 ◽  
Vol 9 (20) ◽  
pp. 4471
Author(s):  
Jianhua Ding ◽  
Qi Yao ◽  
Lei Jiang
Keyword(s):  
Spectral Sensitivity ◽  
Light Sources ◽  
Sensitivity Curve ◽  
P Values ◽  
Practical Applications ◽  
Luminance Difference ◽  
Maximum Value ◽  
Sensitivity Curves ◽  
Conversion Coefficients ◽  
Spectral Sensitivity Curve

Despite the fact that a 2-degree spectral sensitivity curve (SSC) is extensively used in scientific research and relevant applications, the choice between the 10-degree or the 2-degree photopic SSCs in practical applications for the calculation of scotopic/photopic ratios (S/P ratios) depends on actual needs. We examined S/P ratios for more than 300 light sources for correlated colour temperatures (CCTs) from 2000 K to 8000 K and blackbody radiant spectra from 10000 K to 45000 K using 2- and 10-degree SSCs. Results showed that the ratio of the S/P values calculated using the 10-degree and 2-degree SSCs was approximately equal to 0.916. The average mesopic luminance difference increased from 0% to 5.7% at a photopic adaptation luminance from 0.005 to 5 cd/m2. For most practical applications, the mesopic luminance values calculated using these two SSCs were different by several percentage units, yet these differences could be neglected. At extremely high CCTs over 10000 K, the mesopic luminance difference may approximate the maximum value of 16%. This work proposes the conversion coefficients for S/P ratios and the transforming mesopic luminance values calculated for 2- and 10-degree SSC systems. These results may help researchers clarify differences between the S/P ratios calculated using different SSCs.

scholarly journals The Spectral Sensitivities of Single Cells in the Median Ocellus of Limulus

1969 ◽  
Vol 54 (5) ◽  
pp. 636-649 ◽  
Author(s):  
John Nolte ◽  
Joel E. Brown
Keyword(s):  
Visible Light ◽  
Spectral Sensitivity ◽  
Uv Light ◽  
Single Cells ◽  
Chromatic Adaptation ◽  
Sensitivity Curve ◽  
Receptor Cells ◽  
Intracellular Microelectrodes ◽  
Median Ocellus ◽  
Spectral Sensitivity Curve

The spectral sensitivities of single Limulus median ocellus photoreceptors have been determined from records of receptor potentials obtained using intracellular microelectrodes. One class of receptors, called UV cells (ultraviolet cells), depolarizes to near-UV light and is maximally sensitive at 360 nm; a Dartnall template fits the spectral sensitivity curve. A second class of receptors, called visible cells, depolarizes to visible light; the spectral sensitivity curve is fit by a Dartnall template with λmax at 530 nm. Dark-adapted UV cells are about 2 log units more sensitive than dark-adapted visible cells. UV cells respond with a small hyperpolarization to visible light and the spectral sensitivity curve for this hyperpolarization peaks at 525–550 nm. Visible cells respond with a small hyperpolarization to UV light, and the spectral sensitivity curve for this response peaks at 350–375 nm. Rarely, a double-peaked (360 and 530 nm) spectral sensitivity curve is obtained; two photopigments are involved, as revealed by chromatic adaptation experiments. Thus there may be a small third class of receptor cells containing two photopigments.

scholarly journals Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions

2020 ◽  
Vol 35 (4) ◽  
pp. 405-415 ◽  
Author(s):  
Martin Moore-Ede ◽  
Anneke Heitmann ◽  
Rainer Guttkuhn
Keyword(s):  
Spectral Sensitivity ◽  
White Light ◽  
Light Exposure ◽  
Human Subjects ◽  
Light Sources ◽  
Led Light ◽  
Light Spectra ◽  
Timing System ◽  
Circadian Timing System ◽  
Spectral Sensitivity Curve

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000–0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.

Phototaktische Reaktion von Asplanchna priodonta bei monochromatischem Reizlicht/Phototactic Reactions of Asplanchna priodonta to Monochromatic Light

1979 ◽  
Vol 34 (1-2) ◽  
pp. 148-152 ◽  
Author(s):  
Horst Hertel
Keyword(s):  
Spectral Sensitivity ◽  
Monochromatic Light ◽  
Rapid Decrease ◽  
Sensitivity Curve ◽  
Test Light ◽  
Asplanchna Priodonta ◽  
Light Stimuli ◽  
Spectral Sensitivity Curve ◽  
The Way

Abstract 1. The spectral sensitivity curve of the positive phototactic reaction of the rotifer Asplanchna priodon ta has a triple peak. The maxima lie at 363 nm, 453 nm and 552 nm.2. In the shortest wavelength tested and in the area of 453 to 594 nm was the precision of the phototactic orientation found to be high. In between lies a minimum at 395 nm, above 594 nm occurs a rapid decrease in phototactic orientation.3. No wavelength specific differences in the way of orientation were found when using dif­ ferent monochromatic test light stimuli. This leads the same mixture of photopigments.

scholarly journals Ultraviolet-Induced Sensitivity to Visible Light in Ultraviolet Receptors of Limulus

1972 ◽  
Vol 59 (2) ◽  
pp. 186-200 ◽  
Author(s):  
John Nolte ◽  
Joel E. Brown
Keyword(s):  
Spectral Sensitivity ◽  
Electrical Response ◽  
Receptor Potential ◽  
Ion Concentration ◽  
Sensitivity Curve ◽  
Long Wavelength ◽  
Median Ocellus ◽  
Wavelength Light ◽  
Reversal Potentials ◽  
Spectral Sensitivity Curve

In the UV-sensitive photoreceptors of the median ocellus (UV cells), prolonged depolarizing afterpotentials are seen following a bright UV stimulus. These afterpotentials are abolished by long-wavelength light. During a bright UV stimulus, long-wavelength light elicits a sustained negative-going response. These responses to long-wavelength light are called repolarizing responses. The spectral sensitivity curve for the repolarizing responses peaks at 480 nm; it is the only spectral sensitivity curve for a median ocellus electrical response known to peak at 480 nm. The reversal potentials of the repolarizing response and the depolarizing receptor potential are the same, and change in the same way when the external sodium ion concentration is reduced. We propose that the generation of repolarizing responses involves a thermally stable intermediate of the UV-sensitive photopigment of UV cells.

scholarly journals THE RESPONSES OF THE PUPIL OF GEKKO GEKKO TO EXTERNAL LIGHT STIMULUS

1956 ◽  
Vol 40 (2) ◽  
pp. 201-216 ◽  
Author(s):  
E. J. Denton
Keyword(s):  
Light Intensity ◽  
Spectral Sensitivity ◽  
Light Stimulus ◽  
Spatial Summation ◽  
Large Degree ◽  
Absorption Curve ◽  
Sensitivity Curve ◽  
Pupil Response ◽  
Retinal Rod ◽  
Spectral Sensitivity Curve

1. The responses of the pupil of a nocturnal gecko (Gekko gekko) to external light stimulus were studied. 2. The responses of the pupil are determined by light entering the pupil and not by light acting directly on the iris. 3. The responses of the pupil are very uniform in sensitivity including spectral sensitivity for light coming in different directions to the eye. 4. The possible change in area of the pupil is more than 300-fold and probably represents an effort to shield the pure rod retina from saturating light intensities. 5. The pupil continues to contract sharply for changes in external light intensity which give retinal illuminations corresponding to 106 quanta/sec. striking a retinal rod. 6. There is a large degree of spatial summation of the response; circular external light fields subtending 5 and 140° giving the same illumination at the pupil give approximately the same pupil response. 7. The spectral sensitivity curve agrees with the absorption curve of an extracted pigment from a closely related gecko described by Crescitelli in the followig paper. It is similar to the human scotopic curve but its maximum is displaced about 20 to 30 mµ towards the red end of the spectrum. The fall in sensitivity towards the red end of the spectrum is described by the equation See PDF for Equation

Die Wasser- und Ionen-Permeabilität der Zellmembran von Protozoen unter Einwirkung von ultraviolettem Licht / The Permeability of the Protozoan Cell Membrane to Water and Ions under the Action of Ultraviolet Light

1972 ◽  
Vol 27 (10) ◽  
pp. 1243-1257 ◽  
Author(s):  
Eilo Hildebrand ◽  
Hennig Stieve
Keyword(s):  
Membrane Potential ◽  
Membrane Permeability ◽  
Ultraviolet Light ◽  
Spectral Sensitivity ◽  
Morphological Changes ◽  
Membrane Resistance ◽  
Membrane Properties ◽  
Osmotic Gradient ◽  
Sensitivity Curve ◽  
Spectral Sensitivity Curve

The action of ultraviolet light on certain membrane properties of protozoa was investigated in Paramecium, Euplotes, and Opalina using the following methods: observation of morphological changes of the animals, recording of the osmoregulatory organelle (Paramecium), and measurement of membrane potential and resistance by means of intracellularly inserted microelectrodes.This paper presents only slow effects which occur within some minutes after uv irradiation and does not directly concern excitability of protozoa.Due to large uv doses swelling was observed both in Paramecium and Opalina; in Euplotes a liquid-filled vacuole was formed.Small uv doses cause an increase in the frequency of the contractile vacuole of Paramecium; larger doses diminish the frequency reversibly (Fig. 4), and even larger doses lead to an irreversible inactivation of this organelle.Membrane potential and membrane resistance in Opalina are shown to change in different ways under continuous irradiation (Fig. 13): After a transient decrease the membrane potential increases to about the initial value and after this it decreases to zero, whereas the membrane resistance decreases from the beginning of irradiation.The spectral sensitivity curve (Fig. 9) obtained from a standard decrease of the membrane potential shows a maximum at about 280 nm and a rise from 250 nm towards shorter wavelengths.The results indicate an influx of water following the osmotic gradient and an increase of the membrane permeability to cations. With respect to the different behavior of membrane potential and conductivity the mechanism of uv action is discussed. The most probable assumption is that the permeability increases unspecifically but gradually in succession for water, chloride, potassium, and sodium. The possibility of disruption of disulfide links is discussed with respect to the spectral sensitivity curve. It is suggested that the altered permeability is based on photochemically induced changes of the structure of proteins which are either part of the membrane or have an important function in the regulation of the membrane permeability.

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