Introduction To Laser
The laser is a light emitting device that emits light based on the concept of Stimulated radiation. Laser light differs from yhe ordinary light beam.
Ordinary light is not monochromatic. It is incoherent i.e., there is a wide phase difference between the light observed at a point at different times and at different points in space.
The laser beam is highly monochromatic and highly coherent with all the waves exactly in phase with each other and in the same state of polarization. Directionality, monochromacity, intensity, and coherence are the peculiar properties of the laser beam.
Einstein predicted in 1917 that there must be a second emission process to establish thermodynamic equilibrium. He is called this second type emission as stimulated emission. lasers works on the principle of stimulated emission.
The important features of stimulated emission are:
The process of emission is controlled from outside.
The Photons emitted in this process propagated in the same direction as that of the stimulating photon.
The emitted photons have exactly the same phase, frequency, and plane of polarization as those of the incident photon.
The light produced in this process is directional, coherent and monochromatic.
Amplified light or multiplication of photons occurs.
Applications of Lasers:
Spectroscopy, atmospheric remote sensing, Investigating nonlinear optics phenomena, Holographic etc.
Laser-based Light Detection and Ranging(LIDAR) technology have application in geology, seismology, and remote sensing.
The low power semiconductor lasers are used in CD players, laser printers, optical floppy discs, optical memory cards etc.
Laser drilling is a process used alloys and composites.
Laser cutting is a technology that uses a laser to cut materials.
Laser welding: lasers are used in welding of leads of materials such as platinum, sliver etc.
Lasers are also used in Electronics industry, Nuclear plants, Medical applications and surgery etc.