light
Light is electromagnetic radiation in the visible wavelength range between 380 nm( blue) and 780 nm( red). Light is characterized by the color temperature, in which the hue, i.e. the wavelengthof the light, and the brightness are reflected. Normally, only light visible to the human eye is referred to as light. However, non-visible wavelengths such as infrared or ultraviolet also belong to the light wavelengths.
Light propagates in a vacuum at a speed of 300,000 km/s. This speed is called the speed of light (c0). This speed is called the speed of light (c0). In denser media such as glass, this speed is reduced to the value "c". In terms of light distribution, a distinction is made between convergent light, divergent light and diffuse light.
- In computer graphics, light conveys the color impression. The wavelength spectrum of the emitting light source plays the decisive role. Each light source has its own spectrum, which can consist of many individual wavelengths representing different hues, and degrees of saturation. The perceived color is caused by additive color mixing; in the case of an illuminated body, additionally by its color absorptions and reflections.
- Light is also used for optical transmission technology via optical fibers. The wavelengths with the lowest absorption are available for this purpose. These are three wavelength ranges at 850 nm, 1,300 nm and 1,550 nm. These wavelengths lie outside the visible range and are referred to as optical windows.
- The infrared range extends from 780 nm to about 1 µm. However, only the wavelength range near the optical window is used for intelligence purposes. Not every wavelength of the infrared range is equally suitable for data communication. In general, it can be said that there are a number of causes, such as crystalline natural oscillations, which attenuate the infrared radiation to a greater or lesser extent.
