Light is a complex phenomenon classically explained with a simple model based on rays and wavefronts. Many of the aspects of light have been explored, but few people notice them happening in their real lives. For example, most of us observe some type of optical interference almost daily, but usually don't realize the events in play behind the ever-changing display of colors produced when light waves interfere with each other. One of the best examples of interference is shown by the light reflected from a film of oil floating on water. Another example is the thin film of a soap bubble, which reflects a series of light with beautiful colors when shined by natural or man-made light sources.
Electromagnetic radiation(电磁辐射), the larger family of wave-like phenomena to which visible light belongs, is the primary vehicle transporting energy through the vast reaches of the universe. The means by which visible light is sent out or absorbed, and how it predictably reacts under different conditions as it travels through space and the atmosphere, form the basis of the existence of color in our universe. The human eye is sensitive to a form of electromagnetic radiation that lies in the wavelength range between 400 and 700 nanometers(纳米), commonly known as the visible light spectrum, which is the only source of color. When combined, all of the wavelengths present in visible light form colorless white light. Red, green, and blue colors are classically considered the primary colors because they are fundamental to human vision. Light is observed as white by humans when our eyes are affected by equal amounts of red, green, and blue light at the same time.
The concept of color temperature is of great importance in photography and digital imaging, regardless of whether the image capture device is a camera or a microscope. A lack of proper color temperature balance between the microscope light source and the image sensor is the most common reason for unexpected color shifts in photomicrography(显微照相术）and digital imaging. If the color temperature of the light source is too low for the film, photomicrographs will have an overall yellowish or reddish cast and will appear warm. On the other hand, when the color temperature of the light source is too high for the film, photomicrographs will have a blue cast and will appear cool. As problematic as these color shifts may seem, they're always easily corrected by the proper use of conversion and light balancing filters(滤光器）。
