Lasers and Optics

By Adam Abawi

Lasers vs. Light

• A laser differs from other sources of light in that it emits light in a narrow straight line

• A laser consists of a gain medium, a mechanism to energize it, and something to provide optical feedback.

• The energy is typically supplied as an electrical current or as light at a different wavelength.

Lasers and their color in Nanometers

• Red 660-635 nm

• Green 532-520 nm  

• Blue- 405 nm

• Violet 445-405 nm

Lights vs. Corneas

• Studies have found that even low-power laser beams of not more than 5 mW can cause permanent retinal damage if gazed at for several seconds; however, the eye's blink reflex makes this highly unlikely.

• Through their ability to produce temporary or permanent vision loss in varying degrees when aimed at the eyes.

Lights vs. Corneas (Part 2)

• Studies in the early twenty-first century found that the risk to the human eye from accidental exposure to light from commercially available class laser pointers having powers up to 5 mW seemed rather small

What lasers are used for

• Medicine: Bloodless surgery, laser healing, laser eye treatment

• Industries: Welding, making/cutting metals

• Law enforcement: Fingerprints and forensics

• Military: missile defense, radars, marking targets

Everyday Devices that use lasers

• Laser Pointers

• CD-ROM drive

• Laser Pointers

Free Electron Laser

• This laser generate coherent, high power radiation that is widely tunable, currently ranging in wavelength from microwaves through terahertz

• They have the widest frequency range among all of the other lasers.

Chemical Laser

• Powered by a chemical reaction permitting a large of energy to be released  at a fast rate.

• Continuous wave chemical lasers at very high power levels

• Hydrogen fluoride laser transmits 2700-2900 nm

• Deuterium fluoride laser transmits 3800 nm

Fiber Laser

• Solid-state lasers or laser amplifiers

• Guiding of light allows extremely long gain regions providing good cooling conditions; fibers have high surface area to volume ratio which allows efficient cooling.

• Fiber lasers have a fundamental limit in that the intensity of the light in the fiber cannot be so high that optical

Gas Laser

• Gas lasers using many different gases have been built and used for many purposes

• These relatively low cost but highly coherent lasers are extremely common in optical research and educational laboratories.

Solid State Lasers

• Use a crystalline or glass rod which is "doped" with ions that provide the required energy states.

• The usage of the term "solid-state" in laser physics is narrower than in typical use. Semiconductor lasers

Stimulated Emission

• Definition: A transition from the higher to lower energy state in which produces an additional photon.

• Thought up by Albert Einstein

• Transition to the higher state is absorption.

Stimulated Emission

Reflection

• The proportion of light are indicated by the lengths of the solids.

• Law of reflection: The angle of incidence is equal to the angle of reflection

• Critical is 43 degrees for glass

• Prisms- 29.32 degrees(more effective w/ reflection)

Refraction

• Lasers are refracted in prism due to the change in the speed of light as it passes from one medium to another

• The laser beam bends toward the normal when it enters the water