Biophysics Laser Applications Tutorial PDF

BIOPHYSICS (TUTORIAL) Dr. Mahmoud Ismail Dr. Diaa Rayan Biophysics tutorial (week 7) INTRODUCTION TO LASER AND ITS APPLICATIONS Basic for physiotherapy 1 (Lecture 1) LASER IN MEDICINE History of laser  The word laser is an acronym for Light Amplification by the...

BIOPHYSICS (TUTORIAL) Dr. Mahmoud Ismail Dr. Diaa Rayan Biophysics tutorial (week 7) INTRODUCTION TO LASER AND ITS APPLICATIONS Basic for physiotherapy 1 (Lecture 1) LASER IN MEDICINE History of laser  The word laser is an acronym for Light Amplification by the Stimulated Emission of Radiation.  In medicine, it became the "beam that heals" and has been utilized in nearly every discipline of medicine, in diagnosis, therapy, surgery and medical instrumentation. Basic Components of Laser  Laser system consists of three important parts.  1. Active medium or laser medium  2. An energy source (referred to as the pump or pump source)  3. An optical resonator consisting of a mirror or system of mirrors  Types of lasers ž Lasers are classified into 4 types based on the type of laser medium used: ž Solid-state laser ž Gas laser ž Liquid laser ž Semiconductor laser Unique properties of laser (laser Vs light) ž The laser has the following characteristics: ž 1- It is monochromatic. Only light of a single wavelength is produced in the whole process. ž 2- It is coherent. All photons have the same phase and the same polarization; hence they produce an very high intensity. ž 3- It has a very narrow and collimated ray, and hence it is very powerful. Laser power and classification of laser  Light intensity can be expressed in terms of power, measured in watts or milliwatts, or power density, measured in milliwatts per centimeter squared (mW/cm2 ).  Power is the rate of energy flow, and power density is the amount of power per unit area.  lasers have been divided into four classes, according to their power ranges as in following table. Types of laser Solid state laser  Laser medium  Material : can be a glass or crystalline.  The first solid-state laser was a ruby laser.  neodymium-doped yttrium aluminum garnet (Nd:YAG) is most commonly used. Gas laser  Laser medium  In gas laser, the laser medium is made up of the mixture of gases.  Gas lasers are of different types: they are, Helium (He) – Neon (Ne) lasers, argon ion lasers, (CO2 lasers), (CO lasers), excimer lasers, nitrogen lasers, hydrogen lasers, etc.  It produces a laser light beam in the IR region  Gas lasers are used in applications that require laser light with very high beam quality. Liquid laser  Laser Medium and wavelength  A dye laser is an example of the liquid laser.  It produces laser light beam in the near ultraviolet (UV) to the near infrared (IR) region. Semiconductor (diode) laser  Laser Medium  a p-n junction of a semiconductor diode forms the active medium or laser medium.  These lasers are very cheap, compact size ,consume low power and not need mirrors.  in semiconductor lasers, electrical energy is used as the pump source.