141.
The method of achieving population inversion in He – Ne Laser is
A
Optical pumping
B
inelastic Scattering
C
forward biasing
D
chemical reaction
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The method of achieving population inversion in He – Ne Laser is
Optical pumping
inelastic Scattering
forward biasing
chemical reaction
The material in which the population inversion is achieve is called as
Active medium
metastable state
passive medium
stable states
The He - Ne laser is
Continuous Laser
gas Laser
semiconductor laser
pulsed laser
The coherence length of Laser light is
4000 Amstrong
8000 Amstrong
300 m
2 µm
The acute angle between the planes of crystal is
78 degree
71 degree
102 degree
109 degree
Ruby laser produces the laser beam of wavelength
6943 Amstrong
6328 Amstrong
6320 Amstrong
6940 Amstrong
Principle planes in calcite crystals are
squares
rhombus
triangles
parallelograms
Plane of vibration is defined only for
plane polarised
unpolarised
both plane polarised & unpolarised
neither plane polarised & nor unpolarised
Optic axis is
an imaginary line inside the crystal
a real line inside the crystal
a real direction inside the crystal
none of these
O and E waves travel with the same velocity...............in the crystal
parallel to the surface
Perpendicular to the surface
along optic axis
none of the above
Laser radiation is
Monochromatic
Directed in a narrow beam
Produced with large power densities
All of the above
LASER is a short form of
Light Amplification by Spontaneous Emission of Radiation.
Light Amplification by Stimulated Emission of Radiation.
Light Absorption by Stimulated Emission of Radiation.
Light Absorption by Spontaneous Emission of Radiation.
Laser beam is made a of
Electrons
Highly coherent photon
Elastic particles
Excited atoms
In the population inversion
The number of electrons in higher energy state is more than ground state
The number of electrons in lower energy state is more than higher energy state
The number of electrons in lower energy state and higher energy state are same
None of them
In optics, when the vibrations of light are limited to a single two dimensional plane, it is said that light has been what?
Polarised
Plane polarised
Partially polarised
Unpolarised
In double refraction, the vibrations of E ray are confined in
Plane perpendicular to the principle section
Principle section
at an angle ? to the principle section
keeps on changing orientation
In a semiconductor laser, the doping concentration is so high that the Fermi level in N type diode lies
Center of energy gap
Top of valence band
Bottom of conduction band
Inside the conduction band
If the light is made incident on any transparent medium at the polarizing angle, the transmitted light is
unpolarised
Plane polarised
partially Polarised
none of these
If the light is made incident on any transparent medium at the polarizing angle, the reflected light is
unpolarised
Plane polarised
partially Polarised
none of these
If the light is incident on a transparent material at the polarizing angle of 60 degree, The angle of refraction is
45 degree
60 degree
30 degree
90 degree