White Light Source Spectrum

White is a combination of all colors so when we see white the object is reflecting all the colors of light the same.

White light source spectrum.

Sometimes the light bounces around inside the ice crystals before being scattered making the snow seem to sparkle. However it was the invention of the blue led that led to the creation of new efficient white light sources. Some full spectrum light sources are also marketed as emitting ultraviolet uv radiation as well as visible light. Black and white are a bit different from other colors.

When white sunlight enters snow very little of the spectrum is absorbed. The width of the resulting correlogram is the coherence length which depends strongly on the spectral width of the light source. The interference occurs for white light when the path lengths of the measurement beam and the reference beam are nearly matched. For example the sun and other stars are sources of white light.

The frequency of light that we see as red is being reflected and we see that shirt as red. By scanning changing the measurement beam path length relative to the reference beam a correlogram is generated at each pixel. Figure 1 shows the spds of two electric light sources claimed to be full spectrum the duro test vita lite 5500 fluorescent lamp and ge reveal 60w incandescent lamp as well as daylight at 5500k correlated color temperature cct. The sun is the most obvious.

Blue light emitted from such leds can be used to stimulate a wider spectrum of emission from a phosphor layer around the led casing or can be directly combined with red and green leds to create white light.