19-07-2014, 11:27 AM
LASER
[attachment=65990]
Lasers
A laser is a device that can produce a very narrow intense beam of monochromatic coherent light.
The emitted beam is nearly perfect plane wave.
Stimulated Emission
It is pointed out by Einstein that:
Atoms in an excited state can be stimulated to jump to a lower energy level when they are struck by a photon of incident light whose energy is the same as the energy-level difference involved in the jump. The electron thus emits a photon of the same wavelength as the incident photon. The incident and emitted photons travel away from the atom in phase.
This process is called stimulated emission.
Inverted Population
In order to obtain the coherent light from stimulated
emission, two conditions must be satisfied:
Holography
Holography is the production of holograms by the use of laser.
A hologram is a 3D image recorded in a special photographic plate.
The image appears to float in space and to move when the viewer moves.
[attachment=65990]
Lasers
A laser is a device that can produce a very narrow intense beam of monochromatic coherent light.
The emitted beam is nearly perfect plane wave.
Stimulated Emission
It is pointed out by Einstein that:
Atoms in an excited state can be stimulated to jump to a lower energy level when they are struck by a photon of incident light whose energy is the same as the energy-level difference involved in the jump. The electron thus emits a photon of the same wavelength as the incident photon. The incident and emitted photons travel away from the atom in phase.
This process is called stimulated emission.
Inverted Population
In order to obtain the coherent light from stimulated
emission, two conditions must be satisfied:
Holography
Holography is the production of holograms by the use of laser.
A hologram is a 3D image recorded in a special photographic plate.
The image appears to float in space and to move when the viewer moves.