Solution:

Construction and working Ruby Laser:

• Ruby is a crystal of Aluminium oxide (Al2O3) with an addition of 0.05% chromium oxide (Cr2O3).

• Ruby is machined into a rod of about 10 cm in length and 0.5 cm in diameter. One end of the ruby rod is highly silvered and the other end is partially silvered.

• The flash light from the Xenon lamp makes the chromium ions (Cr3+) in the ground state (E0) to go to the meta stable state (E1) by giving out energy in the form of heat.

• From the E1 level the atoms jump to the E0 level, giving out light photons of energy (E1– E0) = h υ.

Uses of Laser :

• Laser is used to find the long distances by direct pulse reflection method. Using this method, the distance between the moon and earth was measured accurately.

• It is used to produce high temperature to melt and vapourise the metals in a very short period.

• It is used to bore holes in hard substances like tungsten and diamond.

• It can be modulated to transmit hundred messages at a time on radio, television and telephone.

• The big size objects like aeroplanes, missiles etc can be destroyed in a few seconds by passing a powerful laser beam on to them. For this reason, laser is called a “Death ray” instrument.

• In surgery, a laser beam is used in spot-welding of a detached retina in the eye ball. It is also used for painless drilling and welding the surface of a tooth to prevent its decay.

• The laser beam is not easily absorbed by water. So it can be used in under-water communication between submarines.