Total Internal Reflection
2007-09-03 14:35:55 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
Because they reflect ALL the light giving us only one image.
Since the angle of reflection is greater than the angle that the light comes in at the entire image is reflected. If this didn't happen then we would get no image or two images superimposed on top of each other.
According to Wikipedia: http://en.wikipedia.org/wiki/Total_Internal_Reflection
"Total internal reflection is an optical phenomenon that occurs when a ray of light strikes a medium boundary at an angle larger than the critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary no light can pass through, so effectively all of the light is reflected. The critical angle is the angle of incidence above which the total internal reflection occurs.
When light crosses a boundary between materials with different refractive indices, the light beam will be partially refracted at the boundary surface, and partially reflected. However, if the angle of incidence is greater (i.e. the ray is closer to being parallel to the boundary) than the critical angle--the angle of incidence at which light is refracted such that it travels along the boundary--then the light will stop crossing the boundary altogether and instead totally reflect back internally. This can only occur where light travels from a medium with a higher refractive index to one with a lower refractive index. For example, it will occur when passing from glass to air, but not when passing from air to glass."
2007-09-03 14:45:10 · answer #1 · answered by Dan S 7 · 0⤊ 0⤋
Internal Reflection is something that degrades the performance of an optical instrument. When reflected or refracted light strikes the walls of the optics holding tube the light is scattered and eventually passes again through the lens or mirror. Because this light has been 'mixed up' and has traveled further that the main image it causes the image to have less contrast and the resolution of the device is reduced.
2007-09-03 22:11:33 · answer #2 · answered by Anonymous · 0⤊ 0⤋
total internal reflection as opposed to what? mirrors? light loss is the reason.
mirrors are used when necessary, due to size and weight, e.g. secondary mirror.
how? using a prism
2007-09-03 21:45:29 · answer #3 · answered by Faesson 7 · 0⤊ 0⤋
Because that affects light transmission, ghost imaging, flare and other abberations.
2007-09-03 22:48:04 · answer #4 · answered by Anonymous · 0⤊ 0⤋