Laser

By :- Manju Bansal

(Light amplification by stimulated emission of radiation)

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

What is a laser??

Characteristics of laser beamMonochromatic

The light emitted from a laser is monochromatic, that is, it is of one wavelength (color).  In contrast, ordinary white light is a combination of many different wavelengths (colors).

Directional Lasers emit light that is highly directional.  Laser light is emitted as a relatively narrow beam in a specific direction.  Ordinary  light, such as coming from the sun, a light bulb, or a candle, is emitted in many directions away from the source.

Coherent The light from a laser is said to

be coherent, which means the wavelengths of the laser light are in phase in space and time.

So how does laser work ??Design

Components of a typical laser:1. Gain medium:-A substance that when excited by energy emits light in all directions. The substance can be a gas, liquid, or semi-conducting material.

2.Laser pumping energy:-For the gain medium to amplify light, it needs to be supplied with energy. This process is called pumping. For ex. electricity from a power supply, flash tubes, lamps, or the energy from another laser.

High reflector:-The optical cavity is used to reflect light from the lasing medium back into itself.  It typically consists of two mirrors, one at each end of the lasing medium.  Light bounces back and forth between the mirrors, passing through the gain medium and being amplified each time.

Output coupler:-The output coupler of a laser is usually a partially transparent mirror on one end of the lasing medium that allows some of the light to leave the optical cavity to be used for the production of the laser beam. 

Laser beam

Laser,_quantum_principle.ogv.360p (1).webm

What happens inside??

Laser types and classification

There are many types of lasers available for research, medical, industrial, and commercial uses.  Lasers are often described by the kind of lasing medium they use - solid state, gas, excimer, dye, or semiconductor.

1) Solid state lasers have lasing material distributed in a solid matrix, e.g., the ruby orneodymium-YAG (yttrium aluminum garnet) lasers. The neodymium-YAG laser emits infrared light at 1.064 micrometers. 

2) Gas lasers (helium and helium-neon, HeNe, are the most common gas lasers) have a primary output of a visible red light. CO2 lasers emit energy in the far-infrared, 10.6 micrometers, and are used for cutting hard materials.

•Excimer lasers (the name is derived from the terms excited and dimers) use reactive gases such as chlorine and fluorine mixed with inert gases such as argon, krypton, or xenon. When electrically stimulated, a pseudomolecule or dimer is produced and when lased, produces light in the ultraviolet range. 

•Dye lasers use complex organic dyes like rhodamine 6G in liquid solution or suspension as lasing media. They are

tunable over a broad range of wavelengths. •Semiconductor lasers, sometimes called diode

lasers, are not solid-state lasers. These electronic devices are generally very small and use low power. They may be built into larger arrays, e.g., the writing source in some laser printers or compact disk players.

Lasers are also characterized by the duration of laser emission - continuous wave or pulsed laser.

CONTINUOUS WAVE (CW) SINGLE PULSED (NORMAL MODE)

LASERS SINGLE PULSED Q-

SWITCHED LASERS REPETITIVELY PULSED OR

SCANNING LASERS MODE LOCKED LASER

USES OF LASERS

In medicine to break up gallstones and kidney stones, to weld broken tissue (e.g. detached retina) to destroy cancerous and precancerous cells;

at the same time, the heat seal off capillaries, to remove plaque clogging human arteries. Surgical treatment

In industry to drill tiny holes in hard materials, for welding and machining, for lining up equipment precisely, especially in inaccessible places.

In military : Marking targets :Missile defenceLaw enforcement: Used for latent fingerprint detection in the forensic identification field

In everyday life to be used as bar-code

readers, to be used in compact

disc players, to produce short pulses of

light used in digital

communications, to produce holograms.

HOLOGRAPHY Holography is the production of

holograms by the use of laser. A hologram is a 3D image

recorded in a special photographic plate.

The image appears to float in space and to move when the viewer moves.

HAZARDS

PROTECT YOUR EYES AND SKIN

In a fraction of a second, your vision can go dark.

NON-BEAM HAZARDS

Non-beam hazards refer to anything other than the laser itself that can create a hazard. This type of hazard includes:

Electrical Hazards Fire Hazards Laser Generated Air Contaminants (LGAC) Compressed Gases Noise

Warning Labels

Class 2: “Laser Radiation – Do Not Stare into Beam.”

Class 2M: “Laser Radiation – Do not Stare into Beam or View Directly with Optical Instruments.”

Class 3R: “Laser Radiation – Avoid Direct Eye Exposure.”

Class 3B:“Laser Radiation – Avoid Direct Exposure to Beam”

Class 4: “Laser Radiation – Avoid Eye or Skin Exposure to Direct or Scattered Radiation.”

Only Class 1 lasers require no labels. All other lasers must be labeled at the beam’s point of origin.

“DANGER” indicates a very dangerous situation that could result in serious injury or death. This sign should be used for Class 3R, 3B, and 4 lasers.

“CAUTION” indicates a potentially hazardous situation which could cause a less serious injury. This sign should be used for Class 2 and 2M lasers.

“NOTICE” does not indicate a hazardous situation. This sign should only be used to make people aware of facility policies regarding laser safety and/or to indicate that a service operation is in progress.

Laser Warning Signs

“CAUTION” Warning Sign

CAUTION

Laser Class and system

Type of Laser, emittedwavelength, pulse duration,and maximum output

Safety Instructions may include:

• Eyewear Required• Invisible laser

radiation• Knock Before

Entering• Do Not Enter When

Light is On• Restricted Area

Safety Instructions

“DANGER” WARNING SIGN

DANGER

Laser Class and system

Type of Laser, emittedwavelength, pulse duration,and maximum output

Safety Instructions may include:

• Eyewear Required• Invisible laser

radiation• Knock Before

Entering• Do Not Enter When

Light is On• Restricted Area

Safety Instructions

“NOTICE” Sign for Laser Repair

NOTICESafety Instructions (such as “Laser Repair inProgress”)

Laser Class and system

Type of Laser, emittedwavelength, pulse duration,and maximum output

Safety Instructions may include:

• Eyewear Required• Invisible laser

radiation• Knock Before

Entering• Do Not Enter When

Light is On• Restricted Area

Control MeasuresThere are several measures that can be taken to

prevent injury from lasers. These measures include:Engineering Controls: Engineering controls are measures that are incorporated into the laser

system and are designed to prevent injury to personnel

Administrative Controls: Administrative controls are procedures that are designed to prevent

personnel from injuryPersonnel Protective Equipment

Warning Signs and Labels

Personnel Protective Equipment

For skin : Ultraviolet lasers and laser welding/cutting

operations may require that tightly woven fabrics be worn to protect arms and hands.

For eyes: Personnel Protective Equipment (PPE) for eyes

exposed to Class 3B or 4 lasers is mandatory. Eyewear with side protection is best.

Thank

you