Reflection is when all of the particles or waves of a beam are returned when the light reaches a boundary between two different mediums.
There are two basic laws that define reflection:
“(1) that the incident ray, the reflected ray, and the normal to the reflecting interface at the point of incidence are all in the same plane
(2) that the angle of incidence equals the angle of reflection”
Refracting telescopes were the
first telescopes ever used. It is said
that two children invented this kind
of telescope, when they were playing
with two lenses. This was perfected
by Galileo. Isaac Newton created
the Reflecting Telescope.
Both telescopes work in the same
way. The difference is that
reflecting telescopes make better
use of mirrors instead of lenses.
The Hubble Space Telescope uses refection to portray images.
When light enters the telescope it is reflected off of large mirrors that are kept in static, dust free environments. Any dirt or dust present would ruin the images collected.
Then the light passes to a secondary mirror which reflects the light to the center of the primary mirror. At the focal point (where the light is focused into one point) the light is set to several different sensors which collect data based on that light.
Hubble Space Telescope's “mirrors are made of glass and coated with layers of pure aluminum (three-millionths of an inch thick) and magnesium fluoride (one-millionth of an inch thick) to make them reflect visible, infra-red and ultraviolet light.”
The mirror can weight almost 2000 pounds.
Examples of Visible Light