Introduction to Lasers

The acronym LASER stands for Light Amplification by Stimulated Emission of Radiation defines the process by which a form of energy is converted into a light energy. The emitted radiation produces over a wide range of the electromagnetic spectrum from the ultraviolet region, the visible, and the infrared region. The range is identified by wavelengths from 100 nanometers to 10.6 micrometers. A wave can be characterized by four properties; wavelength, amplitude, velocity, and frequency. Laser beam emission may be delivered as a continuous wave, pulsed, or Q-switched. This process of stimulated emission was originally described by Albert Einstein in the 1900s

The process of stimulated emission makes laser light unique from ordinary light.  These unique properties of laser included:

Coherent - wave patterns that are locked in phase
Collimated – stays together as a tight beam of light
Monochromatic – produces pure colors of light

Laser System components:

  1. Active medium - what makes the laser
  2. Excitation mechanism – power supply
  3. Feedback mechanism – laser power mirrors
  4. Output Coupler – The front, partially transmissive mirror

Active Mediums:

  1. Solid – Nd;YAG, Ho:YAG, Er:YAG, Er:Glass, YSGG, Ruby, Alexandrite
  2. Gas – CO2, Argon/Krypton, Excimers (excited dimmers - various types), Helium Neon, Copper Bromide (a salt that volatizes into a gas)
  3. Liquid – Dyes (various kinds)
  4. Electronic – Semiconductors – Diode Lasers

Energy Concepts:

Power in WATTS
– a measure of the RATE of energy delivered in Joules/second.

Power Density – Is the amount of power distributed within the area of the spot. Expressed in watts/cm2.
Fluence – An important concept that affects precision during laser surgery. This concept involves three important variable properties – watts, time, and spot size. Utilizing the highest and most appropriate wattage for the shortest time minimizes any damage to adjacent healthy tissues.