Some basic information about laser you should know

Fundamentals:

·   Spartial coherence: Laser beams can have very low divergence in order to concentrate their power at a great distance or can be focused to very tiny spots..

·  Temporal coherence: Laser beams can run continuously or give extremely short pulses with extremly low pulse width from a few microseconds to a few femtoseconds

Nowadays, laser is widely used and essential for different types of industries: manufacturing, food & beverage, medical, military, etc.

Laser physics:

Photon is diffused and amplified through the component of a laser source and is emitted to the surface of materials.

A basic laser system includes:

·   Optical resonator (formed by 2 or more mirrors)

·   Laser medium (gain medium)

·   Energy source (pump source)

SOME COMMON LASER TYPES:

•  Semiconductor Laser: Electrical current, light-emitting diode (in CD, DVD player) or Switching mode power

supply (SMPS) (in telecommunication application)

• ·Solid-State Laser: such as glasses or crystals, using flash lamp, laser diode. Example: Nd:YAG (YAG-Laser), Nd:YVO4 (Vanadate Laser), Nd:YLF, Nd:glass, Yb:YAG, Yb:glass, Ti:sapphire, Cr:YAG and Cr:LiSAF.

• Fiber (Fibre) Laser: Solid-state lasers or laser amplifiers where the light is guided due to the total internal reflection in a single mode optical fiber are instead called fiber lasers. Guiding of light allows extremely long gain regions providing good cooling conditions; fibers have high surface area to volume ratio which allows efficient cooling. In addition, the fiber’s waveguiding properties tend to reduce thermal distortion of the beam.

• Gas Laser: such as carbon dioxide, krypton, argon and mixtures such as helium-neon. These lasers are often pumped by electrical discharge.

LASER SAFETY

Lasers are labeled with a safety class number to identify the class of danger of laser:

·   Class 1: Laser is inherently safe, usually because the light is contained in an enclosure. Example: in CD, DVD players.

·   Class 2: Laser is safe during normal use. The blinking reflex of the eye will prevent damage. Example: laser pointers.

·   Class 3R: Laser is usually up to 5 mW and may cause a small risk of eye damage.

·   Class 3B: Laser can cause immediate eye damage upon exposure.

·   Class 4: Lasers can burn skin, cause eye or skin damage. Therefore, users haves to follow safety regulations and wear safety glasses. Many industrial applications are in this class.