Technologies that Use Light
The Invention of the Telescope



Hans Lippershey invented the telescope
Galileo improved the design and built the most powerful telescope in the world; he was able to see
Jupiter (magnified up to 30X)
Isaac Newton had designed a telescope in which the large convex lens that was normally placed at the
front of the telescope was replaced by a large concave mirror placed at the back of the telescope,
therefore making it lighter
Telescope
Telescope - is an optical device that provides enlarged images of distant objects
Refracting Telescope – is similar in design to a microscope in that they both have two lenses; one on
each end of a long tube. Unlike a microscope, the objective lens in a telescope is the larger lens.
Binoculars – are composed of 2 short refracting telescopes attached together
How does one see an object? - light enters the objective lens, reflects off the reflective prisms
and makes its way out to through the fixed eye piece
Reflecting Telescope – lights enter from one end of a tube and then reflects off a concave mirror to a
small plane mirror. Then the small mirror reflects the light into the eyepiece. This telescope has an
advantage of being a lot lighter.
Microscope
Antonie van Leeuwenhoek – discovered the microscope
Compound microscope – a pair of convex lenses causes a small object to appear magnified when
viewed through the eyepiece
Confocal microscope – is a type of microscope that uses light which uses a laser beam to light the
specimen. The image of the specimen is then digitally enhanced so it can be viewed on a computer.
Cameras
Parts of a Camera
Camera –light proof box with a lens at one end to form a real, inverted image on a film
Shutter – controls the length of time light is allowed in
Diaphragm – the part of the camera that controls the aperture
Aperture- the opening that the light passes through
Camera
diaphragm
aperture
Film
Human Eye
iris
Pupil
Retina
Types of Lenses
Telephoto lens - increases the amount of light that is collected and magnifies a distant object
-
has a long focal length, that is why it protrudes so far out from the camera
Wide Angle Lens – captures a wider angle of view (e.g. trying to take a picture of a bedroom for real
estate)
Pixels – tiny picture elements; when pixels are combined, a continuous image is produced
-the greater the number of pixels, the more closely the image resembles the original object
Digital Image Manipulation
Red Eyes – light from the camera flash passes into the eye, reflects off the red blood vessels inside of the eye,
and then passes out again through the pupil
Lasers
Laser - an optical device that produces a form of light in which all the light rays are almost perfectly parallel
-often used in communications, bar code readers, DVD players etc.
-all lasers are bright enough to do permanent damage to your retina, which is why you never look directly into a
laser beam
-very little energy used to operate lasers
Lasers in Medicine
Detects cancer – forms of cancer produce chemicals which enter the blood stream
-a sample of blood can be taken and shining a laser light through the blood can detect certain kinds of
cancer before they cause symptoms or grow large enough to be detected by an X-ray
Photonics
Photons – tiny packets of energy
Photonics – technologies that make use of the way in which light travels as photons
Solar cells – convert sunlight energy into electrical energy