Photic Environment, Visual Pigments, and the Limits of the Visible Spectrum

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 160-160
Author(s):  
V I Govardovskii
Keyword(s):  
Visible Spectrum ◽  
Blue Shift ◽  
Short Wave ◽  
Visual Pigments ◽  
Limiting Factor ◽  
Spectral Position ◽  
Dark Noise ◽  
Water Fish ◽  
Cone Pigments ◽  
Purkinje Shift

The limits of the visible spectrum are set by the light available for vision, and by the visual pigment absorbance. The hundreds of visual pigments studied to the present day have absorbance maxima spread within the range from 350 to 620 nm. Yet this diversity is used for vision quite nonuniformly: rod and cone visual pigments are tightly clustered around a few preferred positions in the spectrum, eg near 500 nm in the rods of land animals. The so-called ‘sensitivity hypothesis’ assumes that the clustering is to maximise the number of absorbed photons available in the animals' light environment. In most cases, however, visual pigments are substantially more short-wave (blue-shifted) than is necessary for maximum quantal absorption. Examples of the ‘blue shift’ are the Purkinje shift during cone - rod transition in dark adaptation, the hypsochromic shift of rod visual pigments in deep-water fish, and a similar shift in the cone pigments of geckos and some snakes as a result of evolutionary adaptation to nocturnal habits. It is argued that an important limiting factor in vision is the dark noise produced by thermal isomerisation of the chromophore. Measurements of the dark noise in rods with different visual pigments show that the noise increases steeply when the absorbance maximum is shifted to longer wavelengths, thus precluding the use of long-wave pigments for vision at low intensities. The optimum spectral position of a pigment may be that which ensures a maximum light-to-noise ratio in a particular photic environment.

scholarly journals Thresholds and noise limitations of colour vision in dim light

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160065 ◽  
Author(s):  
Almut Kelber ◽  
Carola Yovanovich ◽  
Peter Olsson
Keyword(s):  
Shot Noise ◽  
Colour Vision ◽  
Absolute Threshold ◽  
Colour Discrimination ◽  
Dark Noise ◽  
Visual Threshold ◽  
Light Intensities ◽  
Purkinje Shift ◽  
Dim Light ◽  
Receptor Noise

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod–cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones. This article is part of the themed issue 'Vision in dim light’.

The visual pigments of the bottlenose dolphin (Tursiops truncatus)

1998 ◽  
Vol 15 (4) ◽  
pp. 643-651 ◽  
Author(s):  
JEFFRY I. FASICK ◽  
THOMAS W. CRONIN ◽  
DAVID M. HUNT ◽  
PHYLLIS R. ROBINSON
Keyword(s):  
Color Vision ◽  
Bottlenose Dolphin ◽  
Visual Pigments ◽  
Nucleotide Position ◽  
Long Wavelength ◽  
Terrestrial Mammals ◽  
Cone Opsin ◽  
Cone Pigments ◽  
The Common

To assess the dolphin's capacity for color vision and determine the absorption maxima of the dolphin visual pigments, we have cloned and expressed the dolphin opsin genes. On the basis of sequence homology with other mammalian opsins, a dolphin rod and long-wavelength sensitive (LWS) cone opsin cDNAs were identified. Both dolphin opsin cDNAs were expressed in mammalian COS-7 cells. The resulting proteins were reconstituted with the chromophore 11-cis-retinal resulting in functional pigments with absorption maxima (λmax) of 488 and 524 nm for the rod and cone pigments respectively. These λmax values are considerably blue shifted compared to those of many terrestrial mammals. Although the dolphin possesses a gene homologous to other mammalian short-wavelength sensitive (SWS) opsins, it is not expressed in vivo and has accumulated a number of deletions, including a frame-shift mutation at nucleotide position 31. The dolphin therefore lacks the common dichromatic form of color vision typical of most terrestrial mammals.

scholarly journals Study the Effect of solvent on the Optical Properties Performance of active polymeric laser media

2007 ◽  
Vol 4 (3) ◽  
pp. 387-392
Author(s):  
Baghdad Science Journal
Keyword(s):  
Absorption Spectrum ◽  
Pure Water ◽  
Wave Length ◽  
Blue Shift ◽  
Short Wave ◽  
Fluorescence Yield ◽  
Effect Of Solvent ◽  
Long Wave ◽  
Short Wave Length ◽  
Laser Media

The paper include studies the effect of solvent of dye doped in polymeric laser sample which manufactured in primo press way, which is used as an active (R6G) tunable dye lasers. The remarks show that, when the viscosity of the solvent (from Pure Water to Ethanol), for the same concentration and thickness of the performance polymeric sample is increased, the absorption spectrum is shifts towards the long wave length (red shift), & towards short wave length (blue shift) for fluorescence spectrum, also increased the quantum fluorescence yield. The best result we obtained for the quantum fluorescence yield is (0.882) with thickness (0.25mm) in Ethanol solvent in concentration (2*10-3mole/liter), while when we used the Pure Water as a solvent, we found that the best quantum fluorescence yield is (0.72) at the same thickness & concentration of the sample.

scholarly journals Is the ultraviolet waveband a special communication channel in avian mate choice?

2001 ◽  
Vol 204 (14) ◽  
pp. 2499-2507 ◽  
Author(s):  
Sarah Hunt ◽  
Innes C. Cuthill ◽  
Andrew T. D. Bennett ◽  
Stuart C. Church ◽  
Julian C. Partridge
Keyword(s):  
Mate Choice ◽  
Communication Channel ◽  
Visible Spectrum ◽  
Short Wave ◽  
Zebra Finches ◽  
Long Wave ◽  
Single Cone ◽  
Coloured Filters ◽  
Uv Reflection

SUMMARYThere is growing evidence that ultraviolet (UV) wavelengths play an important role in avian mate choice. One of the first experiments to support this idea showed that female zebra finches (Taeniopygia guttata) prefer UV-reflecting males to males whose ultraviolet reflection has been removed. The effect was very strong despite little or no UV reflection from several plumage areas. However, it is not clear how the importance of the UV waveband compares to other regions of the bird-visible spectrum. We tested whether the response of female zebra finches to the removal of male UV reflection is greater than to the removal of other wavebands. We presented females with a choice of males whose appearance was manipulated using coloured filters. The filters removed single blocks of the avian visible spectrum corresponding closely to the spectral sensitivities of each of the zebra finch’s single cone classes. This resulted in males that effectively had no UV (UV−), no short-wave (SW−), no medium-wave (MW−) or no long-wave (LW−) plumage reflection. Females preferred UV− and SW− males. LW− and MW− males were least preferred, suggesting that female zebra finches show the greatest response to the removal of longer wavelengths. Quantal catches of the single cone types viewing body areas of the male zebra finch are presented for each treatment. Our study suggests it is important to consider the role of the UV waveband in avian mate choice in conjunction with the rest of the avian visible spectrum.

scholarly journals Люминесцентные свойства нестехиометрических кристаллов ниобата лития различного состава и генезиса (обзор)

2022 ◽  
Vol 130 (1) ◽  
pp. 171
Author(s):  
М.В. Смирнов ◽  
Н.В. Сидоров ◽  
М.Н. Палатников
Keyword(s):  
Wave Spectrum ◽  
Visible Region ◽  
Wavelength Region ◽  
Visible Spectrum ◽  
Luminescent Properties ◽  
Short Wave ◽  
Octahedral Cluster ◽  
Short Wavelength Region ◽  
Luminescence Centers ◽  
Near Ir

A brief review of the features of the defect structure and studies of the luminescent properties of nonlinear optical lithium niobate crystals of various compositions and genesis was given. It was established that the electron-hole pair NbNb4+-O- in the oxygen-octahedral cluster NbO6 emitted in the short-wavelength region of the visible spectrum (400-500 nm), while point defects (VLi and NbNb4+-NbLi4+ bipolarons) - in the long-wavelength region (500-620 nm). At the ratio of Li/Nb≈1 the luminescence was extinguished in the visible region of the spectrum due to decreasing the intrinsic luminescence centers. It was shown that the presence of polaron luminescence in the near-IR region (700-1050 nm) was due to the small polarons NbLi4+ and impurity ions Cr3+ localized in lithium and niobium octahedra. The energy transfer between the luminescence centers in the visible and near-IR spectral regions was detected. Moreover, luminescence in near-IR regions was dominant. Doping of LiNbO3 crystals with zinc and magnesium at ZnO<4.46 mol.% and MgO<5.29 mol.% led to decreasing luminescence of intrinsic defects (VLi, NbNb4+-NbLi4+). However, there was an increase of the contribution of the short-wave spectrum component at higher dopant concentrations because of the introduction of Zn and Mg into the origin positions of Nb ions.

Single and multiple visual pigments in deep-sea fishes

1992 ◽  
Vol 72 (1) ◽  
pp. 113-130 ◽  
Author(s):  
J. C. Partridge ◽  
S. N. Archer ◽  
J. Vanoostrum
Keyword(s):  
Deep Sea ◽  
Visual Pigment ◽  
Short Wave ◽  
Visual Pigments ◽  
Outer Segments ◽  
Long Wave ◽  
Retinal Rods ◽  
Pigment Extract ◽  
Sea Fish

The visual pigments in the retinal rods of 17 species of deep-sea fish were examined by microspectrophotometry or visual pigment extract spectrophotometry. In 15 species single visual pigments were found with peak sensitivities between 470 and 490 nm, typical of deep-sea fishes. However, in one species, Stylephorons cordatus, two visual pigments were found with λ values at 470 and 481 nm. In another species, Scopelarchus analis, three visual pigments were found with mean λ values of 444, 479 and 505 nm. The short-wave pigment of this species was found both in main and accessory retinae. It was present both in single rods and in outer segments which had the most long-wave sensitive pigment in their distal parts. It is argued that these two-pigment rods are in the process of changing their visual pigment from a ‘juvenile’ VP505 pigment to an ‘adult’ VP444 pigment. The VP479 was found only as a single pigment in rods in the accessory retina.

scholarly journals Long-term renormalization of chromatic mechanisms following cataract surgery

2004 ◽  
Vol 21 (3) ◽  
pp. 301-307 ◽  
Author(s):  
PETER B. DELAHUNT ◽  
MICHAEL A. WEBSTER ◽  
LEI MA ◽  
JOHN S. WERNER
Keyword(s):  
Cataract Surgery ◽  
Optical Density ◽  
Color Space ◽  
Visible Spectrum ◽  
Crystalline Lens ◽  
Short Wave ◽  
Color Appearance ◽  
Large Shift ◽  
Before And After ◽  
Cataract Patients

The optical density of the human crystalline lens progressively increases with age, the greatest increase in the visible spectrum being at short wavelengths. This produces a gradual shift in the spectral distribution of the light reaching the retina, yet color appearance remains relatively stable across the life span, implying that the visual system adapts to compensate for changes in spectral sensitivity. We explored properties of this adaptive renormalization by measuring changes in color appearance following cataract surgery. When the lens is removed, cataract patients often report a large perceptual shift in color appearance that can last for months. This change in color appearance was quantified for four cataract patients (63–84 years) by determining the chromaticity of stimuli that appeared achromatic before surgery, and at various intervals after surgery for up to 1 year. Stimuli were presented on a calibrated CRT as 9.5-deg spots, with 3-s duration and 3-s interstimulus intervals (ISIs). Chromaticity was adjusted by the subjects in CIE L*a*b* color space with luminance fixed at 32 cd/m2, on a dark background. We also estimated the optical density of the cataractous lens by comparing absolute scotopic thresholds from 410 nm to 600 nm before and after surgery. The results demonstrated that immediately following surgery there is a large increase in the short-wave light reaching the retina, mainly below 500 nm. The achromatic settings generally showed an initial large shift in the “yellow” direction after surgery that gradually (but never fully) returned to the original achromatic point before surgery. The shifts in the achromatic point occur over a number of months and appear to occur independently of the fellow eye.

scholarly journals Characterization of CdS Nanoparticles Synthesized Using Microwave-Assisted Polyol Method

2013 ◽  
Vol 667 ◽  
pp. 122-127 ◽  
Author(s):  
Nayereh Soltani ◽  
Elias Saion ◽  
Mohd Zobir Hussein ◽  
Robiah Bt. Yunus ◽  
Manizheh Navaseri
Keyword(s):  
Irradiation Time ◽  
Visible Spectrum ◽  
Blue Shift ◽  
Polyol Method ◽  
Molar Ratio ◽  
Cds Nanoparticles ◽  
Microwave Assisted ◽  
Uv Visible ◽  
Scherrer Formula ◽  
Average Size

Synthesis of cadmium sulfide (CdS) nanoparticles has been performed through the simple and rapid microwave-assisted polyol method, using cadmium chloride and thioacetamide as the cadmium and sulfur sources respectively. Attempts were made to control the size and crystallinity of the CdS nanoparticles by controlling microwave irradiation time and the initial molar ratio of the cadmium and sulfur sources. The structure of nanoparticles characterized by X-ray diffraction (XRD) was hexagonal. No peaks corresponding to impurities were detected, indicating the high purity of the product. The size of the prepared samples was calculated by Debye–Scherrer formula according to XRD spectra. The morphology of particles was observed in the transmission electron microscopy (TEM) images was spherical. The average size of nanoparticles was also estimated from these images. The optical absorption of CdS nanoparticles studied by UV-Visible spectroscopy showed a blue shift from bulk CdS due to quantum confinement. The size of nanoparticles was calculated by Brus formula according to UV-Visible spectrum and compared to XRD and TEM results.

scholarly journals The absorption of light by the coloured globules in the retina of the domestic hen

1929 ◽  
Vol 105 (738) ◽  
pp. 371-374 ◽  
Keyword(s):  
Scattered Light ◽  
Wave Length ◽  
Visible Spectrum ◽  
Short Wave ◽  
Alternative View ◽  
Short Wave Length ◽  
Full Explanation ◽  
Absorption Of Light ◽  
Specific Receptors ◽  
Domestic Hen

Schultze (1866) pointed out that the coloured globules in the retinæ of birds might afford a means wherby stimulation of the cones would be restricted to certain regions of the visible spectrum (7). A few other investigators have ascribed sensual discrimination of colour to retinal filters situate in front of the specific receptors fro light (1, 4 and 6). An alternative view (2, 3) regards the coloured globules as decreasing, merely generally and relatively unselectively, i. e. , quantitatively rather than qualitatively, the amount of light of short wave-length which reaches the sensitive (outer) limb of the cones. This might possibly be useful by reducing the amount of the more highly scattered light and so might improve the visibility of distant objects (2). This, however, can hardly be the full explanation, for if the function of the coloured globules be merely to reduce the amount of the more refrangible end of the spectrum the various globules need not be of more than one colour.

ANOMALOUS SPECTRAL SHIFTS OF INDIRECT EXCITONS IN COUPLED GaAs QUANTUM WELLS

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3606-3610 ◽  
Author(s):  
D. W. SNOKE ◽  
V. NEGOITA ◽  
D. HACKWORTH ◽  
K. EBERL
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Low Frequency ◽  
Blue Shift ◽  
Substrate Material ◽  
Excitation Density ◽  
Spectral Position ◽  
Indirect Excitons ◽  
Spectral Shifts ◽  
Resonant Laser

We have studied the energy shifts of indirect excitons consisting of an electron in one quantum well and a hole in an adjacent quantum well. Several surprising effects occur: (1) a very strong blue shift with increasing intensity of resonant laser excitation, (2) a very strong red shift with weak magnetic field, and (3) very low-frequency (sub-Hz) fluctuations of the spectral position at high excitation density. We discuss the effect of screening by carriers excited in the substrate material.

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