Monochromatic light filters for the visible spectrum

1928 ◽  
Vol 206 (1) ◽  
pp. 101
Author(s):  
Walter C. Holmes
Keyword(s):  
Monochromatic Light ◽  
Visible Spectrum ◽  
Light Filters

scholarly journals Environment and Sporulation in Phytopathogenic Fungi IV. The Effect of Light on the- Formation of Conidia of Peronospora Tabacina Adam

1963 ◽  
Vol 16 (1) ◽  
pp. 88 ◽  
Author(s):  
IAM Cruickshank
Keyword(s):  
Light Source ◽  
Monochromatic Light ◽  
Continuous Light ◽  
Visible Spectrum ◽  
Phytopathogenic Fungi ◽  
Time Of Day ◽  
Light Conditions ◽  
Low Light ◽  
Maximal Inhibition ◽  
Effect Of Light

Using a leaf�disk technique, an analysis of the effect of light on the sporulation intensity of P. tabacina was carried out. The following points were demonstrated: (I) Under conditions of continuous light, sporulation of P. tabacina is sensitive to very low light intensities. ED5!1 for inhibition of sporulation was 16 ftvV cm- 2 for incandescent light (4 f,c.), and 0�58 p.W cm-2 for a monochromatic light source (469 mpo) in the region of maximum effectiveness. (2) Dark treatments induced sporulation under otherwise continuous light conditions. The response was directly proportional to the length of the exposure to darkness over the period 1�5-7 hr. (3) The time of day at which sporulation occurred could be modified by adjustment of the time of day at which darkness was initiated. (4) Within the visible spectrum, the region exerting maximal inhibition on sporulation occurred at 450-525 mJL.

The roles of filters in the photophores of oceanic animals and their relation to vision in the oceanic environment

1985 ◽  
Vol 225 (1238) ◽  
pp. 63-97 ◽  
Keyword(s):  
Sea Water ◽  
External Surface ◽  
Red Light ◽  
Visible Spectrum ◽  
Transmission Band ◽  
Spectral Absorption ◽  
Good Match ◽  
Mesopelagic Zone ◽  
Light Filters ◽  
Colour Match

In many of the photophores found in deep-sea fishes and invertebrates, light filters containing pigments lie between the tissues that generate light and the sea. The loss of light within such filters has been measured throughout the visible spectrum for a variety of animals. These filters differ greatly in their spectral absorption characteristics and do not all contain the same pigments. All those from ventral photophores have a transmission band in the blue corresponding to the daylight that penetrates best into oceanic waters. For two fishes it is shown that the light generated inside their photophores is a relatively poor spectral match for the ambient submarine daylight while the light emitted into the sea, after passing through the filters, is a good match. For a third fish a similar improvement in ‘colour match’ is brought about not by passing the light through a filter containing pigments but by reflecting the light into the sea by a blue mirror. All these observations support the hypothesis that the ventral photophores are used for camouflage. Malacosteus niger Ayres 1848 is an oceanic fish which emits red light from a large suborbital photophore. The red light generated inside the photophore is largely absorbed by a coloured filter over its external surface which transmits only a band of light of wavelengths around 700 nm. This is a waveband which is heavily absorbed by oceanic sea water. It is shown, however, that animals that can emit and are sensitive to such far-red light will have very great advantages in being able to see without being seen. The ranges over which such red light can be useful for vision are, however, relatively small. The nature of the pigments found in these various photophores is discussed. It is also calculated that the intensities of penetrating daylight are such that visual acuity could be fairly good down to considerable depths in the mesopelagic zone.

scholarly journals Measurement of rotatory dispersive power in the visible and ultra-violet regions of the spectrum

1908 ◽  
Vol 81 (550) ◽  
pp. 472-474 ◽  
Keyword(s):  
Photographic Plate ◽  
Monochromatic Light ◽  
Green Light ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Narrow Strip ◽  
In Series ◽  
Limited Scale ◽  
Dispersive Power ◽  
Constant Deviation

The following is a brief preliminary account of improvements effected in the method of determining rotatory dispersive power which have made it possible to observe accurately not only in the bright regions of the visible spectrum, but throughout the scale from the region of the lithium red line into that commanded by the photographic plate. Two methods have generally been used for the purpose, namely, (1) Broch’s method, in which a spectroscope is arranged in series with the polarimeter and a narrow strip of a continuous spectrum is picked out for observation—a method which is much improved by using a constant-deviation spectroscope in place of one of the variable-deviation type, and .(2) Landolt’s method, in which a white light is reduced by means of filters to approximate homogeneity in the red, green, light-blue, or dark-blue parts of the spectrum. Neither method fulfils the fundamental condition that the field of the polarimeter shall be uniformly lighted with monochromatic light—many of the measurements that have been made, therefore, possess only a qualitative value. A much better method is due to the late Sir William Perkin, who introduced the use of a spectroscope-eyepiece as a means of purifying the sodium light, and used it on a limited scale for measuring rotatory dispersive power in the red (lithium), yellow (sodium), and green, thallium) parts of the spectrum.

Monochromatic light filters to enhance biomass and carotenoid productivities of Dunaliella salina in raceway ponds

2021 ◽  
pp. 125689
Author(s):  
Emeka G. Nwoba ◽  
Tarannom Rohani ◽  
Mohammadjavad Raeisossadati ◽  
Ashiwin Vadiveloo ◽  
Parisa A. Bahri ◽  
...  
Keyword(s):  
Dunaliella Salina ◽  
Monochromatic Light ◽  
Light Filters ◽  
Raceway Ponds

THE SPECIFIC EFFECTS OF MONOCHROMATIC LIGHT ON THE GROWTH OF YEAST

1930 ◽  
Vol 2 (4) ◽  
pp. 249-263 ◽  
Author(s):  
A. H. Hutchinson ◽  
Dorothy Newton
Keyword(s):  
Growth Rate ◽  
Rapid Growth ◽  
Monochromatic Light ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Light Stimulation ◽  
Specific Effects ◽  
Rapid Growth Rate ◽  
Sudden Transition

An isolated strain of Yeast, derived from Fleischman's preparation, when exposed to monochromatic light responds quite differently to light of different wave-lengths. Slight retardation in growth by red and orange light, stimulation by yellow and green, and increasingly marked retardation in the blue and violet, characterize the effects of the mercury lines of the visible spectrum. There is a sudden transition to stimulation in the near ultra-violet. (λ 3984 Å). Stimulation continues at λ 3650 Å and characterises the region λ 2894 Å to λ 2700 Å, but otherwise the lines employed in this investigation retard growth.Generally the effect either of stimulation or retardation is greater when the control is one of rapid growth rate, but the reverse is the case at the red end of the visible spectrum.

scholarly journals Impact of coherent light on interaction of fungi and bacteria cells cultivated in vitro

2020 ◽  
Vol 23 ◽  
pp. 02001
Author(s):  
Andrey V. Budagovsky ◽  
Marina V. Maslova ◽  
Olga. N. Budagovskaya ◽  
Ekaterina V. Grosheva
Keyword(s):  
Pseudomonas Syringae ◽  
Monochromatic Light ◽  
Spatial Coherence ◽  
Pathogenic Fungi ◽  
Neon Laser ◽  
Helium Neon Laser ◽  
Light Filters ◽  
Spatio Temporal ◽  
Helium Neon

This article considers impact of coherent red quasi-monochromatic light on interaction of colonies of the Pseudomonas syringae bacteria and the Fusarium macroceras fungus in an in vitro culture. A helium-neon laser and a heat source with a system of light filters and aperture diaphragms were used for irradiation. Two light fluxes were obtained with energy parameters close in magnitude, but significantly different in spatio-temporal coherence. Light with a high statistical ordering stimulated growth of both colonies. Irradiation from the same spectral range and intensity, but with low spatial coherence, increased the functional activity of only small bacteria cells. As a result, there was a suppression of larger fungal cells development that were interacting with them. Therefore, it was the statistical (coherent) properties of light that affected the change in the equilibrium of microorganisms in an artificial biocenosis. This approach can be used in practice for increasing the activity of bacteria antagonists of pathogenic fungi and the non-chemical disease protection of plants.

Influence of near-ultraviolet radiation on reproductive and immunological development in juvenile male Siberian hamsters

2001 ◽  
Vol 204 (14) ◽  
pp. 2535-2541
Author(s):  
George C. Brainard ◽  
John P. Hanifin ◽  
Felix M. Barker ◽  
Britt Sanford ◽  
Milton H. Stetson
Keyword(s):  
Monochromatic Light ◽  
Visible Spectrum ◽  
Short Photoperiod ◽  
Juvenile Male ◽  
Natural Habitats ◽  
Long Wavelength ◽  
Near Ultraviolet ◽  
Photoperiodic Regulation ◽  
Photon Pulse ◽  
Visible Wavelengths

SUMMARY The aim of this study was to characterize the lenticular ultraviolet transmission of the Siberian hamster (Phodopus sungorus) and to probe the range of near-ultraviolet (UV-A, 315–400nm) and visible wavelengths (400–760nm) for modulating the photoperiodic regulation of its reproductive and immune systems. Ocular lenses from adult hamsters were found to transmit UV-A wavelengths at similar levels to visible wavelengths, with a short-wavelength cut-off of 300nm. Five separate studies compared the responses of juvenile male hamsters to long photoperiods (16h:8h L:D), short photoperiods (10h:14h L:D) and short photoperiods interrupted by an equal photon pulse of monochromatic light of 320, 340, 360, 500 or 725nm during the night. The results show that UV-A wavelengths at 320, 340 and 360nm can regulate both reproductive and immune short-photoperiod responses as effectively as visible monochromatic light at 500nm. In contrast, long-wavelength visible light at 725nm did not block the short-photoperiod responses. These results suggest that both wavelengths in the visible spectrum, together with UV-A wavelengths, contribute to hamster photoperiodism in natural habitats.

Spectral Sensitivity of Chromatophores in Diadema Setosum (Leske)

1957 ◽  
Vol 34 (2) ◽  
pp. 222-225
Author(s):  
MASAO YOSHIDA
Keyword(s):  
Spectral Sensitivity ◽  
Monochromatic Light ◽  
Visible Spectrum ◽  
Diadema Setosum

1. The spectral sensitivity of the chromatophores of Diadema setosum (Leske) was studied, using monochromatic light. 2. The chromatophores are most sensitive in the region of the visible spectrum between 450 and 500 mµ with a maximum at 470 mµ.

The Raman Spectrum of Rubber

1935 ◽  
Vol 8 (4) ◽  
pp. 521-521
Author(s):  
S. D. Gehman
Keyword(s):  
Raman Effect ◽  
Monochromatic Light ◽  
Ultra Violet ◽  
Light Filter ◽  
Oxidation Products ◽  
Colloidal Structure ◽  
Light Filters ◽  
Wide Range ◽  
Continuous Background ◽  
Viscous Solutions

Abstract It has been previously reported that the Raman effect is exhibited by rubber as a continuous scattering together with the presence of broad bands (Franklin and Laird, Phys. Rev., 36, 147 (1930); Busse, J. Phys. Chem., 36, 2862 (1932)). Busse attributed this result to the viscosity of the solutions or to the possibility that the rubber groups respond to a wide range of frequencies. However, viscous solutions of polysterol in carbon tetrachloride give a line spectrum (Signer and Weiler, Helv. Chim. Acta, 15, 649 (1932)). As to the second explanation, this does not seem to be the nature of the Raman effect (Bär, Helv. Phys. Acta, 4, 369 (1931); Bär, Z. Physik, 79, 455 (1932)). The Raman effect has been investigated extensively for terpenes other than rubber. The bands and continuous background for rubber appear to be due to fluorescence of impurities, oxidation products, or the rubber hydrocarbon. The acetone extract of rubber is fluorescent as observed in ultra-violet light. The intensity of the bands and background for rubber decreases as the rubber is purified. However, acetone extraction and two diffusions with ethyl ether did not remove the fluorescence entirely, as could be seen by examination between complementary light filters. Some of the background is undoubtedly unmodified radiation, that is, Tyndall scattering by the colloidal structure and by motes. This can be reduced by a monochromatic light filter.

Sign in / Sign up

Export Citation Format

Share Document