Vision peak sensitivity

Eye resolution depends on many factors, including color, brightness, contrast, and length of exposure. On the axis, resolutions of around 5 arcmin are required to reach the region of peak sensitivity. Acuity increases rapidly as the object moves outside the central 2° region. It is principally sufficient only to provide the central field of vision with detailed pictures because the natural resolution of the eye in the periphery strongly decreases. At 10° off-axis eccentricity, acuity drops around 10 arcmin (Helman 1993). 

Their distribution is not uniform across the retina. There are three types of cone, each having different spectral sensitivities. The ) -cones have peak sensitivities in the blue part of the spectrum, the y-cones peak in the green, and the p-cones in the yellow-green. These different sensitivities to wavelength provide the basis for color vision. 

Figure 5.5.10-2 compares the typical putative spectrums based on such a linear analysis, (3, y, p compared to the actual chromophores, Rhodonines 5, 7 9 [with Rhodonine(l 1) shown for completeness. It is not significant in human vision except for aphakic patients.] Hunt describes the (3,y p spectrums as probable sensitivity curves of the three types of cones. He did not discuss any rod spectrum in his figure. The probable sensitivity curves appear to have been normalized individually. The peak in the p spectrum appears to be at a longer wavelength than frequently suggested. However, it is still at too short a wavelength to support the known spectral response of the human eye as illustrated by the Photopic Luminosity Function. 

The amount of ambient light absorbed by two different dyes is given in Fig. 14 for an AH 1.5 and an incandescent spectrum. For dye number 1 the emission peak occurs at the maximum of the sensitivity of the human eye for photopic vision. 

XPS measurements were carried out on an AXIS NOVA photoelectron spectrometer (Kratos Analytical, Manchester, UK). The surface atomic concentration was determined firom peak areas using sensitivity factors. Spectrum background was subtracted according to Shirley. The XPS peaks of the Ti species were analyzed by spectra deconvolution software (CasaXPS-Vision 2, Kratos Analytical, UK). 

In the pigment epithelium of the retina, all-/ra j-retinol is isomerized to 11-cm-retinol and oxidized to 1 l-at-retinaldehyde. This reacts with a lysine residue in opsin, forming the holoprotein rhodopsin. Opsins are cell type specific they shift the absorption of 11-a r-retinaldehyde from the ultraviolet (UV) into what we call, in consequence, the visible range — either a relatively broad spectrum of sensitivity for vision in dim light (in the rods) or more defined spectral peaks for differentiation of colours in bright light (in the cones). 

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