ASCI 511 Remote Sensing

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ASCI 511Remote Sensing

• Session 1
• Miscellaneous

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Fluorescence

• This is luminescence that occurs where the energy
  is supplied by electromagnetic radiation, usually
  ultraviolet light.
• The energy source kicks an electron of an atom
  from a lower energy state into an "excited"
  higher energy state.
• Then the electron releases the energy in the form
  of light, or luminescence, when it falls back to
  the lower energy state.

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Type of Fluorescence

• Photoluminescence
• fluorescence caused by a beam of photons, or
  light.
• Cathodoluminescence
• fluorescence excited by an electron beam (as
  opposed to a beam of photons).
• An example is a cathode ray tube (CRT)

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Type of Fluorescence

• Thermoluminescence
• fluorescence (actually a phosphorescence)
  stimulated by the application of heat, to
  temperatures below those that result in
  incandescence.

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Type of Fluorescence

• Chemiluminescence
• fluorescence that results from chemical energy
  released during a chemical reaction. The "Glow
  Sticks" widely found on the market today glow for
  hours after the stick is "broken" to allow the
  two chemicals inside to mix. The mechanism is
  very similar to that used by fireflies on summer
  evenings.
• Triboluminescence
• fluorescence that results from scratching or
  abrading a substance, as when two pieces of
  quartz are rubbed together to produce light.

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Example of Cathodoluminescence
Night Owl Light (http//www.x10.com/products/eno_n
olt3_s.htm)
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Example of CathodoluminescenceHow an IR Night
Scope Works

• Available light is gathered by the front
  objective lens, where it is transmitted through a
  set of optical lenses to the Electronic
  Intensifier Tube (EIT).

• High levels of energy, produced by the device's
  complex power supply, knock out electrons from
  the photocathode screen, located on the front of
  the electronic intensifier tube.
• The same energy creates a highly static field,
  pushing the electrons to the phosphorescent
  screen, a sensitive layer, located on the back of
  the EIT.
• These electrons strike the phosphorescent screen
  with great speed, causing the screen to
  illuminate.

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Example of CathodoluminescenceHow an IR Night
Scope Works Cont.

• This process produces an image, which is then
  magnified by the ocular lens located at the back
  of the device.
• By looking through the ocular lens you will see
  the image as if you just looked through a regular
  optical device, except the image will appear in a
  monochrome green color.
• Finally, the ocular lens provides adjustment for
  your particular eyesight, while the objective
  lens lets you adjust the focusing distance to the
  object you are viewing.

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References
The Thomas S. Warren Museum of Fluorescence,
(http//www.sterlinghill.org/warren/aboutfluoresce
nce.htm) Night Owl Light Scope,
(http//www.x10.com/products/eno_nolt3_s.htm)