Search results for "spectral sensitivity"

Effect of Color on Contrast Sensitivity with Two Different Accommodative Stimuli

1993

We studied the influence of color and accommodation on the contrast sensitivity function (CSF). At the same time, we measured the effect of axial chromatic aberration (ACA) on the CSF. The CSF's of two observers were determined using red, green, blue, and white light, at 5- and 0.5-m viewing distances. At 5 m the CSF's were measured with natural vision and also with lenses which compensated the ACA. Results show that the effect of ACA on the CSF is to reduce the sensitivity to blue with respect to the red. The difference in sensitivity between these two colors is between 50 and 150% and varies with the frequency and the subject. When the ACA is compensated the influence of the color on the …

Aluminium nitrate ceramics: a potential UV dosemeter material.

2002

The ceramic material AlN-Y 2 O 3 is proposed as a potential ultraviolet radiation (UVR) dosemeter using optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL). Experimental studies have shown that AlN ceramics exhibit attractive characteristics suitable for practical UV dosimetry applications. The features are: (1) the spectral sensitivity covers the 200-350 nm range, in the UV-B region it is similar to that of human skin; (2) the angular dependence of the incident radiation follows the cosine law; (3) high yields of both UVR-induced OSL and TL signals compared to those of Al 2 O 3 :C; and (4) a large dynamic range TL signal (5 orders of magnitude). Although ther…

An ultraviolet receptor as a fourth receptor type in goldfish color vision

1985

Comparison of the sensitivity to spectral variation of voltage- and current-matched tandem devices with luminescent coupling and thickness optimizati…

2016

Using models that do not take luminescent coupling into account, voltage-matched tandem devices have previously been shown to be less sensitive to spectral variation than their current-matched counterparts. The present paper compares the spectral sensitivity of voltage-matched and current-matched tandem devices by applying a detailed balance model that takes luminescent coupling into account. Current-matched stacks where the thickness of the top cell thickness has been optimized are also considered. The main finding is that luminescent coupling reduces the difference in spectral sensitivity between voltage-matched and current-matched devices. There is still a significant difference, however…

Multicolour LEDs in educational demonstrations of physics and optometry

2014

LED light sources are used to design experimental setup for university courses teaching human color vision. The setup allows to demonstrate various vision characteristics and to apply for student practical exercises to study eye spectral sensitivity in different spectral range using heterochromatic flicker photometry. Technique can be used in laboratory works for students to acquire knowledge in visual perception, basics of electronics and measuring, or it can be applied as fully computer control experiment. Besides studies of the eye spectral sensitivity students can practice in trichromatic color matching and other visual perception tasks

Absence of lightness constancy as a deficit of monochromatic vision

1995

Dark-adapted human subjects arranged a collection of colored papers in a sequence according to their lightness. The sequence of the papers (which appeared gray to the subjects) varied under different illuminant spectra. These variations could be predicted quantitatively from the radiometric data and human scotopic spectral sensitivity. By substitution of natural daylight spectra in the computation it was shown that monochromats cannot perceive lightness reliably under the changing illuminant spectra of our planet. Animals need some degree of lightness constancy to detect figures against a background reliably. This can be achieved only with the help of additional light receptors of different…

Wavelength dependence of the optomotor response in zebrafish (Danio rerio)

2003

Abstract The action spectrum of motion detection in zebrafish (Danio rerio) was measured using the optomotor response in the light adapted state. The function has a single maximum at 550–600 nm, and is similar to the spectral sensitivity function of the L-cone type in the mid and long wavelength range. At shorter wavelengths the values of three of the five fish tested are lower. As in goldfish [Vis. Res. 36 (1996) 4025], the result indicates a dominance of the L-cone type with an inhibitory influence of M- or S-cones. Experiments with a red/green striped cylinder showed that the optomotor response was at minimum whenever the L-cone type was not modulated by the moving pattern. This demonstr…

Single Out-of-Resonance Dielectric Nanoparticles as Molecular Sensors.

2021

Light scattering from single nanoparticles and nanostructures is a commonly used readout method for nanosensors. Increasing the spectral sensitivity of resonant nanosensors to changes in their local surrounding has been the focus of many studies. Switching from spectral to intensity monitoring allows one to investigate nonresonant or out-of-resonance dielectric nanoparticles. Here, we systematically compared such dielectric silica nanoparticles with plasmonic gold nanorods by deriving analytical expressions and by performing experiments. The experiments show a similar sensitivity for the detection of an adsorbate layer for both particle types, which is in good agreement with theory. The fla…

Wavelength dependence of visual acuity in goldfish.

2003

Visual acuity was measured in a two-choice training experiment with food reward. Four goldfish were trained to select a homogeneously illuminated testfield when a high-contrast grating (transparency) was shown for comparison at the second testfield. Measurements were performed for white and monochromatic testfield illuminations in the light adapted state. Fourteen wavelengths between 404 nm and 683 nm were tested. For each wavelength (and white light) the testfield intensity was determined for which spatial resolution was highest. Between 446 nm and 683 nm maximal values of 2.0 cycles/deg (corresponding to a visual acuity of 15' of arc) were found. At 404 nm and in the ultraviolet resolutio…

Stimulated luminescence of AlN ceramics induced by ultraviolet radiation

2001

Abstract Properties of thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) of the ceramic material AlN-Y 2 O 3 have been studied after exposure to ultraviolet radiation (UVR). The dosemeter material Al 2 O 3 : C has been used for comparative measurements. The spectral sensitivity of the samples has been studied and compared with spectral effectiveness of the UVR-induced biological processes. It has been shown that a very high yield and linear dose response characterise the UVR-induced TL from AlN-Y 2 O 3 . Although lower than the TL, the OSL signal from UV-exposed AlN-Y 2 O 3 is still higher than that of Al 2 O 3  : C in a broad spectral region. The possibilit…