Wednesday, April 27, 2011

Describing the role of the pentaprism in the DSLR mentioned a total internal reflection of light. We explain this phenomenon accessibly as possible. Let shown here is a cross sectional drawing of an aquarium filled with water. From the bottom of the aquariumthrow a beam of light toward the surface. The direction of the beam determines the angle between the normal (perpendicular) to the water surface and the radius. This angle is called the angle of incidence at the border facilities (water and air).

For small angles of incidence, such as the angle marked in blue, light comes out of thewater and continues through the air.
For a certain angle, called for the border (marked in red), the beam will not go out of the water and "slides" over the surface,
For angles of incidence greater than the critical angle the light reflected from the surface of the water and returns to it. Reflection is completely lossless, ie there is no loss of energy. Hence the name of total internal reflection

This phenomenon occurs whenever the light goes from the center of the denser (with higher refractive index) to the rarer and therefore such
- from water to air
- glass into the air
The phenomenon of internal reflection całkowitegoo is the basis for the construction of fiber optics. In a thin rod of glass or transparent plastic light can travel without any loss of energy very long distance, bouncing off the walls in succession from the bar.