The document discusses the laser and how it works. It describes how a laser emits light through optical amplification using stimulated emission of photons. Lasers produce light that has a high degree of spatial and temporal coherence. A laser works by stimulated the emission of photons within an active medium placed between two mirrors, which results in the amplification of the photon waves into a coherent beam of light.

2. Light Amplification by Stimulated Emission of Radiation
It is a device that emits light(Electromagnetic Radiation) Through the process
called OPTICAL AMPLIFICATION based on the stimulated emission of photons
The laser light is notable for its high degree of spatial and temporal coherence
LOSER
“Light Oscillation by Stimulated Emission of Radiation”
the FIRST and more CORRECT term for LASER

3.  Charles H. Townes, James P. Gordon, and H. J. Zeiger built the
first ammonia maser at Columbia University in 1953. This device
used Stimulated Emission in a stream of energized ammonia molecules to
produce amplification of microwaves at a frequency of about 24.0
GHertz.
 Townes later worked with Arthur L. Schawlow to describe the principle
of the optical maser, or LASER, which Theodore Maiman created the first
working model of in 1960. For their research in the field of stimulated
emission, Townes, Basov and Prokhorov were awarded the Nobel Prize
in Physics in 1964.

5.  Developed by Theodore H. Maiman in 1960
 Creates a beam at λ = 694 nm (deep red).
 Metastable state of ~3ms
 Has efficiency of less than 1% but creates a diameter
 ranging from 1 mm to about 25 mm, so a large energy
 density is achieved in the laser beam.
 Used by rangefinders in 1960, until the more efficient Nd:YAG
came a Decade later
 It is now used for drilling holes in diamonds
 It is the first laser made functional

6.  • Monochromaticity – same λ or frequency
 • Directivity
 • Highly correlated photons for long distances.
 • High energy-density
 • Polarization
 • Modes

9.  • Gaseous laser :
 - atomic gaseous lasers (e.g. HeNe)
 - molecular laser (e.g. CO2)
 • Dye laser (e.g. N2
 - rhodamine)
 • Electronic laser (uses the acceleration of
electrons)
 • Solid laser – semiconductor (YAG-Nd laser
 Neodymium:Yttrium Aluminium Garnet)
 • Atomic laser – Bose-Einstein condensate.

16. Laser Typical λ Range Pulse or CW
HeNe 1.15µm-633nm IR-Visibile CW
CO2 9.4-10.6µm IR CW
Dye 360-720nm IR-UV Pulse
Electronic 1mm-1nm Microwaves - CW
Xray
YAG:Nd 940-1440nm IR BOTH

17.  Science – precise measurements, spectroscopy
 Medicine – laser scalpel, eye surgery
 Industry – cutting and welding, guidance
systems
 Arts – etching
 Telecommunications (fiber optics)
 Radars
 Precise measurement of long distances (e.g.
Moon)
 Consumer – CDs, DVDs, laser lights

19.  A magnifying glass (simple magnifier) is a
converging lens. It allows us to focus on objects
closer than the near point, so that they make a
larger, and therefore clearer, image on the
retina.

21.  A refracting telescope consists of two lenses at
opposite ends of a long tube. The objective lens
is closest to the object, and the eyepiece is
closest to the eye.

24.  Astronomical telescopes need to gather as
much light as possible, meaning that the
objective must be as large as possible. Hence,
mirrors are used instead of lenses, as they can
be made much larger and with more precision.

25.  A terrestrial telescope, used for viewing objects
on Earth, should produce an upright image.
Here are two models, a Galilean type and a
spyglass:

26.  A compound microscope also has an objective
and an eyepiece; it is different from a telescope
in that the object is placed very close to the
eyepiece.

27.  There is a certain range of distances over which
objects will be in focus; this is called the depth
of field of the lens. Objects closer or farther will
be blurred