The answer to this question in the research report CIES009/E: 2012 released by the International Commission on Illumination (CIE) in 2002 is that blue light can cause photochemical damage to the retina, mainly concentrated in the pigment inner epidermal cells of the retina and forming arcs and blind spots on the retina.
The reason why the eyes can see things is because there are rod cells and cone cells distributed on the retina. Among them, there is a place at the end of the retinal axis called the fovea, which is the area with the sharpest vision and the richest visual cells. The reason why it appears yellow is because it is rich in lutein. Under normal circumstances, aging of the macula flava can cause visual impairment as one ages. However, under long-term exposure to blue light, excessive blue light directly enters the retina and produces a large amount of free radicals, causing accelerated oxidation of the macular fossa, ultimately leading to a large number of visual cell death in the macular fossa, which cannot be repaired on its own.
Even the warm colored light emitted by daily incandescent lamps still contains blue light, which means that blue light is commonly present in various lamps and light sources, with the only difference being that blue light does not contain much of other colors. Moreover, it should be pointed out that white LED relies on blue light to excite the fluorescent powder and emit yellow red light, which then fuses its own blue light to form white light. Therefore, the proportion of its blue light component will be relatively more concentrated than other types of light sources.
Although the maximum frequency that can be discerned by the human eye is approximately 60Hz, it is difficult to distinguish between 60Hz, 100Hz, and 3000Hz luminous frequencies based on vision. But as the old saying goes, what cannot be seen is not necessarily harmless. Numerous studies have shown that prolonged exposure to hazardous light sources and flickering environments can lead to mild eye fatigue and visual impairment, and severe cases include dizziness, nausea, and damage to the nervous system.
Due to the fact that both incandescent and fluorescent lamps operate directly at power frequency, their luminous frequency is approximately around 100Hz (waveform shown in Figure 5), and the upper limit of the standard for the non hazardous fluctuation depth at this frequency is set at 3.3%. However, relying solely on thermally stable incandescent lamps or fluorescent lamps with afterglow from fluorescent powder is difficult to meet this requirement.
On the other hand, due to the ease of dimming and the ability to integrate multiple chips in a single lamp, LED can achieve better color reproduction and reduce visual fatigue.
Finally, it is advisable to choose lighting products with light diffusers (milky white frosted covers) as much as possible. Below is a set of comparative data, and we can see that the same sample number, white and black, represents the results with and without a frosted cover, respectively. It can be seen that after removing the frosted cover, the blue light radiance generally increases by 10 to 100 times.
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