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EnChroma glasses were invented incidentally in 2002 by Donald McPherson while trying to develop lenses to protect and aid surgeons during laser operations. The company received a grant from the NIH in 2005, the glasses were released to the public in 2012 and cheaper versions in 2014. [ 4 ]
dBm or dB mW (decibel-milliwatts) is a unit of power level expressed using a logarithmic decibel (dB) scale respective to one milliwatt (mW). It is commonly used by radio, microwave and fiber-optical communication technicians & engineers to measure the power of system transmissions on a log scale , which can express both very large and very ...
The user alternates looking between the two lenses and can infer a color by the relative brightness changes between the two lenses and direct vision. For example, red-green colorblind subjects routinely confused green and orange; using the SeeKey, orange would appear lighter through the red filter and darker through the green filter (relative ...
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Kapron et al. reported in 1970 fibers having an attenuation coefficient of ~20 dB/km at 0.632 μm, [5] and Miya et al. reported in 1979 ~0.2 dB/km attenuation at 1.550 μm. [6] Nowadays, silica optical fibers are routinely manufactured with an attenuation of <0.2 dB/km with Nagayama et al. reporting in 2002 an attenuation coefficient as low as ...
A typical OPM is linear from about 0 dBm (1 milli Watt) to about -50 dBm (10 nano Watt), although the display range may be larger. Above 0 dBm is considered "high power", and specially adapted units may measure up to nearly + 30 dBm ( 1 Watt). Below -50 dBm is "low power", and specially adapted units may measure as low as -110 dBm.
The preceding review of the several errors of reproduction belongs to the Abbe theory of aberrations, in which definite aberrations are discussed separately; it is well suited to practical needs, for in the construction of an optical instrument certain errors are sought to be eliminated, the selection of which is justified by experience. In the ...
However, if glasses frames are thicker and so significantly protrude from the face, an eye relief over 17 mm should be considered. Eyeglasses wearers should also look for binoculars with twist-up eye cups that ideally have multiple settings, so they can be partially or fully retracted to adjust eye relief to individual ergonomic preferences. [35]