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Laser Study Notes

A laser is a device that emits coherent light through stimulated emission, characterized by being monochromatic, coherent, and highly directional. Key components include an active medium, energy source, and optical resonator, with various types such as solid-state, gas, liquid, and semiconductor lasers. Lasers have numerous applications in communication, industry, medicine, defense, and research, but come with advantages like high precision and disadvantages such as high costs and safety hazards.

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56 views3 pages

Laser Study Notes

A laser is a device that emits coherent light through stimulated emission, characterized by being monochromatic, coherent, and highly directional. Key components include an active medium, energy source, and optical resonator, with various types such as solid-state, gas, liquid, and semiconductor lasers. Lasers have numerous applications in communication, industry, medicine, defense, and research, but come with advantages like high precision and disadvantages such as high costs and safety hazards.

Uploaded by

mkumar847104
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Laser - Detailed Study Notes

Definition

A laser is a device that emits a beam of coherent light through the process of stimulated emission of

electromagnetic radiation. The emitted light is typically monochromatic, coherent, and highly directional.

Basic Properties of Laser Light

1. Monochromatic - Single wavelength or color.

2. Coherent - All light waves are in phase.

3. Highly Directional - Travels in a narrow, straight beam.

4. High Intensity - Focused energy in a small area.

Principle of Laser

Laser works on Einstein's theory of stimulated emission of radiation. The key processes involved:

- Absorption: Atom absorbs a photon and jumps to a higher energy level.

- Spontaneous Emission: Excited atoms return to lower states by emitting a photon.

- Stimulated Emission: Excited atom emits an identical photon when hit by another photon.

Laser action is possible when stimulated emission dominates over absorption.

Essential Components of a Laser

- Active Medium: Provides atoms for excitation (e.g., Ruby, He-Ne gas).

- Energy Source: Supplies energy (e.g., flash lamp, electrical discharge).

- Optical Resonator: Two mirrors amplify light via reflection.

Types of Lasers

Based on Medium:

- Solid-State: Ruby, Nd:YAG

- Gas: He-Ne, CO

- Liquid (Dye): Rhodamine dye

- Semiconductor: Diode laser

Based on Operation:
Laser - Detailed Study Notes

- Continuous Wave (CW) Laser

- Pulsed Laser

Important Laser Types

- Ruby Laser: Solid-state, red light (694.3 nm), pulsed.

- He-Ne Laser: Gas laser, red light (632.8 nm), continuous.

- Nd:YAG Laser: Infrared (1064 nm), used in surgery and industry.

Population Inversion

Condition where more atoms are in excited state than in ground state. Necessary for laser action. Achieved

via optical pumping, electrical discharge, or chemical reaction.

Applications of Lasers

In Communication: Optical fiber, satellite communication

In Industry: Cutting, welding, barcode scanners

In Medicine: LASIK, cancer treatment, dentistry

In Defense: Laser-guided missiles, range finding

In Research: Holography, spectroscopy, nuclear fusion

Advantages

- High precision

- Non-contact processing

- Minimal damage to surroundings

- Long-distance communication

Disadvantages

- Expensive setup

- Safety hazards

- Requires precise control

- Bulky systems
Laser - Detailed Study Notes

Safety with Lasers

Lasers are classified into 4 classes. Class 3B and 4 are hazardous and require safety measures like goggles

and enclosures.

Interesting Facts

- Term 'laser' coined in 1959.

- First laser: Ruby laser by Theodore Maiman in 1960.

- Laser light can match sun's intensity.

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