INTRODUCTION TO LASER Lesson Note

The diagram below shows the major parts of a simple laser device:

Explanation of the parts:

● Energy Source (Pump): Supplies energy (e.g. from a flash lamp or electric current) to excite the atoms in the active medium.

● Active (Gain) Medium: The material (solid, liquid, gas, or semiconductor) in which atoms are excited to produce light — e.g. ruby crystal, helium-neon gas, or semiconductor material.

● Fully Reflective Mirror: A mirror at one end of the tube that reflects all the light back into the cavity.

● Partially Reflective Mirror: A mirror at the other end that reflects most of the light back but allows a small portion (the laser beam) to pass out as the output.

● Optical Cavity (Resonator): The space between the two mirrors where the light bounces back and forth, gaining strength (amplification) before it is emitted.

MEANING OF LASER

Laser stands for “Light Amplification by Stimulated Emission or Radiation”. It is a device that makes atoms or electron give off electromagnetic radiation. This radiation has a specific wavelength and is then made stronger, producing a narrow range of light unlike other types of light, the light from a laser has the same frequencies a wavelength making a narrow beam of light, beams of light is produced. The branch of optical physics lays the foundation of quantum electrons. “The laser beams have a property similar to that light wave emitted all at once.

They are coherent and usually of one wavelength or color. A laser is a device that increases the intensity of light by focusing in a particular direction. Some laser produces visible light and some produce ultraviolet or infarred rays.

Laser light differs from ordinary light because of the following special properties:

● Monochromatic : Laser light consists of only one wavelength (one colour), unlike ordinary light which is a mixture of many wavelengths. A light beam which contains a single wavelength photon that’s originate from natural light sources contains a range of emerges wavelength and colour

● Coherence: Visible light receives its emission from excited electrons[electron of the higher energy level] are move down to the lower energy level [ground state]

● Directionality : In conventional light source like lamps, torch light, electric bulbs e.t.c photons move at random point. As such these source scatter, light in all possible directions. The laser emit light in a particular focused direction.

● High Intensity (Brightness): Because the light energy is concentrated in a narrow beam, laser light is far more intense and powerful than ordinary light of the same energy. The light of a laser is focused in a particular direction.

There are many types of lasers and they are categories based on the type of medium at which they are used. This can be Solid, Liquid, Gas and Semi-conductors.

These types of lasers are typically used for the target destination system by military application.

N.B. These are other type of laser and they include chemical laser and metal vapour laser.

● It is used in medicine for delicate surgeries (e.g. eye surgery, removal of tumors) with high precision and minimal damage to surrounding tissue.

● It is used in industry for cutting, welding, drilling and engraving hard materials with high accuracy.

● It is used in communication (fibre optics) to transmit large amounts of information over long distances quickly and with little loss.

● It is used in barcode scanners and laser printers in commerce and offices, making work faster and more accurate.

● It is used in scientific research and measurement, e.g. measuring long distances (surveying) and in laboratories.

● It is used in military applications, such as laser-guided weapons and range finders.

● It is used in entertainment, for laser light shows and in optical devices like CD/DVD players.

● It can cause serious and permanent eye damage (blindness) if the beam enters the eye directly, since it can burn the retina.

● It can cause skin burns when high-power laser beams come in contact with the skin.

● It can start a fire if directed at flammable (combustible) materials, due to its concentrated energy.

● Laser equipment and its maintenance are generally expensive.

● It can be misused as a weapon or for harmful purposes if it falls into the wrong hands.

● Some laser devices require highly trained/skilled personnel to operate safely, which may not always be readily available

A laser is a device that produces a highly concentrated, monochromatic, coherent and directional beam of light through the process of light amplification by stimulated emission of radiation. Lasers exist in different types depending on their active medium — solid, gas, liquid, and semiconductor. While lasers have numerous advantages in medicine, industry, communication and research, they must be handled with care because of their potential to cause eye damage, skin burns, and fire outbreaks.