LASER

Which of the following is an example of optical pumping?

• Ruby laser

• Helium-Neon laser

• Semiconductor laser

• CO₂ Laser

When laser light is focussed on a particular area for a long time, then that particular area alone will be heated.

• TRUE

• FALSE

The life time of an excited state in case of metastable state is......... sec

• 10^-6

• 10^-3

• 10^-8

• 10^-5

Which of the following is not a characteristic of LASERS?

• Monochromatic

• Coherent

• Divergent

• Intense

The lower energy levels contains more atoms than the upper level under the conditions of

• population inversion

• Thermal Equilibrium

• pumping

• isothermal packaging

Example of solid state laser is

• None of these

• He-Ne

• GaN

• Rhodamine

............... is formed by two parallel reflecting mirrors , which is used to amplify the laser.

• Active medium

• Pumping

• Optical resonators

• Optical filters

Which pumping method is used in He-Ne laser?

• optical

• electrical excitation

• Chemical pumping

• Direct Conversion

Which of the following is a four-level laser?

• ND: YAG

• Ruby

• He-Ne

• Semiconductor laser

Lasers are different with respect to the ordinary light in terms of it

• Reflection

• Refraction

• Polarization

• Scattering