Download Applications of Optics - RosedaleGrade10Science

Applications of Optics
Purpose: To research technologies based on the principles of optics.
Topics
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Periscope
Fiber optic cable
Binocular
Hologram
Kaleidoscope
Endoscope
Retro-reflector
Overview: Form a group of 4-5 individuals. You will be given one topic to research.
Summarize the main points of the article and then write down your points on the poster
paper.
Notes:
Technology
Periscope
Fiber optic cable
Research notes
Binocular
Hologram
Kaleidoscope
Endoscope
Retro-reflector
Retro-reflector
A retro-reflector a device or surface that reflects light back to its source in the same
direction from which it came.
Retroreflection is usually obtained in the following way:

with a set of three mutually perpendicular mirrors that form a corner (a corner
reflector or corner cube)
Corner retro-reflectors occur in two varieties. In the more common form, the corner is
literally the truncated corner of a cube of transparent material such as conventional
optical glass. In this structure, the reflection is achieved either by total internal reflection
or silvering of the outer cube surfaces. The second form uses mutually perpendicular flat
mirrors bracketing an air space. These two types have similar optical properties.
Retroreflection (sometimes called retroflection) is used on road surfaces, road signs,
vehicles, and clothing (large parts of the surface of special safety clothing, less on
regular coats).
The Laser Ranging Retro Reflector (LR3) was a retro-reflector left on the moon by Apollo
11 astronauts. With this device scientists have been able to shine a beam at the Moon
bounce it off LR3 and determine the earth-moon distance to within a few millimetres.
The Apollo 11 Lunar Laser Ranging Experiment
Reflective clothing
Binoculars
The first binoculars were generally too long and clumsy to work very well. In 1854, Italian
inventor Ignatio Porro came up with a brilliant idea. Instead of passing the light straight
through the tubes from end to end, Porro realized he could make the tubes much shorter
by bouncing the light around inside.
Porro’s design, which is still used today in many binoculars, uses two prisms to change
the direction of the light beams inside the binocular tubes. The prisms also flip the image
so that, unlike in a normal telescope, the image doesn’t end up upside-down when it
reaches your eyes. At the front of each binocular is a lens—either an objective or a field
lens. The objective or field lens magnifies the image .
Fiber optic cables
Fiber-optic lines are strands of optically pure glass as thin as a human hair that carry
digital information over long distances. They are also used in medical imaging and
mechanical engineering inspection.
The light in a fiber-optic cable travels through the core (hallway) by constantly bouncing
from the cladding (mirror-lined walls), a principle called total internal reflection.
Because the cladding does not absorb any light from the core, the light wave can travel
great distances.
However, some of the light signal degrades within the fiber, mostly due to impurities in
the glass.
Endoscope
Endoscopes consist of two distinct layers, an inner core and an outer layer of cladding.
The higher refractive index core will reflect light waves off it's boundaries when the angle
of incidence exceeds the critical angle for that particular material (core). The cladding
helps to maintain all of the light within the endoscope and a black sheath over the
endoscope will mean light from the external environment will not enter. As the light
enters at an angle greater than the critical angle it will be totally internally reflected and
bounce along the walls of the tubes. In this way, light is able to be bent around corners.
Kaleidoscope
The kaleidoscope is a tube of mirrors containing loose coloured beads or pebbles, or
other small coloured objects. The viewer looks in one end and light enters the other end,
reflecting off the mirrors. Typically there are two rectangular lengthways mirrors. Setting
of the mirrors at 45° creates eight duplicate images of the objects, six at 60°, and four at
90°. As the tube is rotated, the tumbling of the coloured objects presents the viewer with
varying colours and patterns. Any arbitrary pattern of objects shows up as a beautiful
symmetric pattern because of the reflections in the mirrors. A two-mirror model yields a
pattern or patterns isolated against a solid black background, while a three-mirror
(closed triangle) model yields a pattern that fills the entire field.
Holograms
If you want to see a hologram, you don't have to look much farther than your wallet. There are holograms on most driver's licenses, ID cards and credit cards.
A reflection hologram is a special kind of hologram in which a three dimensional image is
visible when seen from a particular angle. It is only at this particular angle that a normal
hologram is visible as a three dimensional and multicolor hologram. In a reflection
hologram, how the hologram is visible in its three dimensional and multicolored version
is dependent on the angle of light and the angle of the hologram. To be more precise
and correct, it is the angle of the object beam and the reference beam.
How the hologram is visible in its three dimensional and multicolored version is
dependent on the angle of light and the angle of the hologram. To be more precise and
correct, it is the angle of the object beam and the reference beam. In a reflection
hologram, the image is stored inside an emulsion. This emulsion stored image is
viewable only when white light falls on it. The image is reconstructed only at the point
and time of the interaction of two beams of light, namely object beam and the reference
beam, traveling in opposite directions. If the light falling onto the hologram is not at the
accurate angle required to make the image visible, the hologram, by itself, selects the
beam of light, that is falling on the required angle for it to be seen in multi-color and three
dimension form, and then reconstructs the image. The extra light passes through the
hologram without being reflected.
Periscope
A periscope's basic purpose is to allow submarine crews to see objects above the water
while the ship remains submerged. A simple periscope can be constructed out of a
vertical tube with mirrors placed at a 45-degree angle at the top and bottom of the tube.
These devices basically collect light from an image and direct that light from one mirror
at the top of the periscope to the mirror at the bottom of the periscope.
A periscope's basic purpose is to allow submarine crews to see objects above the water
while the ship remains submerged. A simple periscope can be constructed out of a
vertical tube with mirrors placed at a 45-degree angle at the top and bottom of the tube.
These devices basically collect light from an image and direct that light from one mirror
at the top of the periscope to the mirror at the bottom of the periscope.
A periscope uses triangular prisms to change the direction of light twice.