Natural and Artificial Light
When sunlight is directed through a prism and onto a screen, it is separated into a rainbow pattern on the screen. The colors are arranged in this rainbow pattern beginning with red, followed by orange, yellow, yellow-green, green-blue, blue, blue-violet and finally violet. This pattern is called the optical spectrum and represents the part of the electromagnetic spectrum visible to human eyes. Other parts of the spectrum invisible to human eyes include the infrared part of the spectrum which we can feel as warmth on skin, and the ultraviolet part of the spectrum which can be recorded on photographic film. These parts of the spectrum are utilized in a variety of ways. The portion of the optical spectrum which human beings perceive as brightest is yellow-green light with a frequency of 555nm.
The intensity of light is perceived as brightness or darkness and serves as the basis for the brain's judgment of the light level. (Refer to the Standard Comparative Visual Sensitivity Chart)
Understanding Artificial Light
Artificial light sources are light sources which artificially combine just the necessary components of the optical spectrum. The way in which these components are combined determines the color rendering of the light source and thereby affects the way in which objects appear when illuminated with the light source
The Three Primary Colors of Light
Artificial light can be created by combining red (R), green (G) and blue (B) components as shown in the illustration.
Changes in the RGB ratios change the characteristics of the light and therefore the mixture ratios of RGB fluorescent substances is an important point to be taken into consideration when creating artificial lights
Three Band Fluorescent Lamps
HG X lamps are three band fluorescent lamps which apply the three primary colors of light. These bright lamps were developed to provide exceptional color rendering characteristics by increasing the yellow-green component which emphasizes brightness perception as compared with conventional fluorescent lamps and more carefully balancing the R, G and B components of the light
Why are Tunnels Colorless Worlds?
The orange colored low-pressure sodium vapor lights often used in tunnels provide monochromatic orange light Therefore your eyes perceive brightness but are unable to discriminate between colors