Photometrics is a hybrid of physics and biology as it measures visible light based on a statistical (very Gaussian very un-Newtonian) sensitivity curve. What it also does implicitly is to consider our subjective experience of light more than the objective. It is our fortune that the subjective experience can tricked! Of course the source needs to be specially made to be able to do all this as in this case retinal persistence is not enough alone as a switching frequency of 30Hz will cause flicker and even at several KHz though there is no flicker, the light dims in relation to its duty cycle. But as Tesla once said, the solution is to be found in high voltage high frequency domain. And so it was that a particular and secret manufacturing process known only partially to three people in the world and the special waveform can aid the retina to do its energy saving job. The “frame roll” frequency. You may have discovered, while rummaging in your computer, a dialog box defining the properties of your screen: This most likely shows a screen refresh frequency of 60Hz. This is the “rod cooling rate” and also the number of times the picture is entirely redrawn on the screen each second. This rod cooling rate is the frequency above which no rod is able to detect the difference between a moving picture and reality. Indeed at lower frequencies there are risks of epileptic fits and migraine. Above 72Hz is better for eye strain relief. The phenomenon of retinal persistence is exploited all around you: in your TV, in your computer, at the movies. Everything that you distinguish possesses a frequency that adapts to your viewing mechanism. Some things can appear different from reality thanks to our interpretation. The new technologies use the properties of the retinal persistence more and more. And now Night Sun® takes advantage of biology, like the Lumières did a century ago, and in the same spirit as the Moving Pictures Expert Group (MPEG) did in compressing moving images in MPEG4/DivX to get more movie for your byte, the team at have got more flash for your buck. Needless to say, there’s much, much more to it than that… What is Scotopically Enhanced Lighting? Amazingly, the very central part of the retina, the fovea, contains only cones. In the rest of the retina there are both rods and cones, with the number of rods dominating the cones by about 10 to 1. Historically, lighting manufacturers have utilized light meters to determine a lamp’s lumen output that are calibrated by examining the eye's sensitivity to only cone activated vision in the very central part of the retina, the fovea (photopic). These light meters completely ignore the effect of rod activated vision (scotopic). As a result, lighting practice accepted this single sensitivity function because it was erroneously assumed that the more light sensitive rods only functioned at very dim light levels, those experienced during the night even in presence of street lighting. Recent studies now demonstrate unequivocally and in an objective manner that rod photoreceptors are active not only in dim light but also at typical interior light levels as well (see The Technical Data below). Vision scientists have known that the rods are more sensitive than cones to bluish-white light sources which is a characteristic found in higher colour temperature light sources. This explains why environments using warm white (3000K) and even cool white (4100K) fluorescent lighting appear less bright than the same environment lit by lamps of a higher colour temperature, 5000K or above. Therefore, combining the Photopic and Scotopic lumen of a particular light source is more akin to how the human eye perceives light at normal interior light levels. Additional studies over the past 15 years have concluded that general lighting with high scotopic to photopic ratios (S/P), characterized by high colour temperature lamps, provide better visual acuity. As detailed further below, lamps with high S/P ratios can result in faster reading time, reduced visual fatigue, reduced glare, a reduction in task orientated errors, and improved human performance.