Types Of Laser Outputs

Types of Laser OutputsTypes of Laser Outputs

1) Continuous-Wave (CW)

Continuous with respect to time

Higher level must be long-lived relative to lower level, else the laser is self-terminating.

2) Pulsed (not continuous)Higher peak powers (kW to > MW)

Nanosecond pulse widths are typcial


3) Q-Switched“Giant pulse laser”

Spoil the cavity resonance so that the lasing threshold is greatly exceeded. Then let it out all at once.

Hundreds of MW/pulse achieved


4) Mode-LockedPicosecond or less laser pulsesForce all longitudinal modes to be

coherent

Generates short (ps or less) and intense (MW) pulses

Varieties of LasersVarieties of LasersLaser type Wavelengths (nm) Power Output

Helium–neon 633,1152 0.1–50 mW CW

Argon–ion 351–529 several 5 mW–25 W CW

Helium–cadmium 325, 442 1–50 mW CW

Dye (Ar pump) 400–1000 to 5 W CW, tunable

Yd:YAG 1064 0.1–500 W (ave) Pulsed

Nd:YAG 1064 0.5–1000 W CW

CO2 10 600 1–100 W 3–7 CW

GaAlAs 750–900 1–100 mW CW

InGaAsP 1100–1600 1–100 mW CW

Ti:sapphire 700–1100 0.1–1 W CW, tunable

(Ar pumped)

What You Should Know About Lasers?What You Should Know About Lasers?

What does “LASER” stand for?

What does population inversion mean? Why is it required for lasing?

Be able to draw the energy diagram for a 3 and 4 level laser.

What are the characteristics of laser light?

What are the differences between “CW” and “pulsed” lasers (operational modes)?

What are the general types of lasers (e.g., gas, excimer, etc)?

What is a transverse mode?

UP DOWN BACK 23/4/12

BecomeEnlightened

(14)


Guiding LightGuiding Light

Your guide to navigating through the wonders of laser technology….

I. Introduction

II. History of the Laser

III. How the Laser Works

IV. Laser Activity

V. Implications of the Technology• Medical• Industrial• Entertainment• MilitaryVI. Conclusions

VII. Resources

23/4/12UP DOWN BACK

IntroductionIntroductionIn the Beginning There Was LightIn the Beginning There Was Light

Industrial Cutting Tools

CD Players

DVD Players

Dental Drills

Lasik eye surgery

Tattoo Removal

Surgical Cutting Tool

Printers

And More…


IntroductionIntroductionIn the Beginning There Was LightIn the Beginning There Was Light

The laser is an example of a technology that was developed long before its applications were ever imagined. Forty-four years ago Arthur Schawlow and Charles Townes could have had no possible way of

knowing the profound effects this technology would have on society or the widespread applications it would have in a variety of industries.

The impact of this invention is usually not realized because many consider laser technology a futuristic idea depicted in Hollywood

movies or science fiction books. Most people don’t recognize that laser technology is already present as an integral part of our daily lives,

allowing us to listen to CD’s, watch DVD’s, and play computer games. Additionally, lasers are becoming increasingly visible in medicine in ophthalmologic, cosmetic, and general surgery. This presentation

focuses on giving the viewer better insight to the impacts this technology has had on society as a whole as well as an understanding of

the functions lasers play in our daily lives.


Flashes of BrillianceFlashes of BrillianceThe History of the LaserThe History of the Laser

“A splendid light has dawned on me” – Albert Einstein

In 1917 Einstein published ideas on stimulated emission of radiation. These ideas laid the basic foundation for the

invention of the laser years later. While investigating what is now known as the photo-electric effect, Einstein noted a statistical tendency which caused photons (particles of light), to want to move together. In addition, emitted photons displayed a sort of snowball effect, once emitted, photons stimulated other atoms to emit more photons. Einstein was also able to prove that these emitted photons all traveled in the same direction and with the same frequency as the original photon.

(11)

23/4/12UP DOWN BACK

Flashes of BrillianceFlashes of Brilliance

The Birth of the MaserThe Birth of the Maser

The immediate predecessor to the laser was the maser, a device designed using the same principles that were eventually applied in creating the laser. The word “MASER” is actually an acronym which stands for:

M icrowave A mplification by S timulated E mission of R adiation

Critics of this lengthy and costly project adopted the following acronym

Means of Acquiring Support for Expensive Research! !

At the point in time when the laser was being invented, other researchers had no

idea how widespread the applicationsof the laser would become.

On the left the patent application for the maser is pictured.

(17)


Flashes of BrillianceFlashes of Brilliance

From Maser to LaserFrom Maser to Laser

Arthur L. Schawlow Charles H. Townes

The laser is credited as being invented in 1958 by Charles H. Townes and Arthur L. Schawlow. Townes coined the term “laser” with help from his students. The main differentiating factor between the two devices is that the laser uses light waves as opposed to the microwaves utilized by the maser.

Einstein’sTheories

Right typeof atoms

ReflectingMirrors

Laser = + +

Click on this picture to see how a laser works

Back toGuiding

Light(12)

23/4/12UP DOWN BACK

Shedding Some LightShedding Some Light How the Laser WorksHow the Laser Works

Flash Tube

Partially ReflectiveMirror

Mirrored Surface

Atoms

The laser in it’s non-lasing state

become excited

The flash tube fires light at the ruby rod. The light excites the atoms.

Emitted Light

Some ofthese atoms

emit photons.


Shedding Some LightShedding Some Light How the Laser Works Cont.How the Laser Works Cont.

Some of these photons run in a direction parallel to the ruby's axis, so they bounce back and forth off the mirrors.

As they pass through the crystal, they stimulate emission in other atoms. Monochromatic, single-phase, columnated

light leaves the ruby through the half-silvered mirror -- laser light!

Back toGuiding

Light


Can You See the Light?Can You See the Light?

In the picture on the next slide try to identify as many occurrences of laser technology as possible. When you are ready to see how many applications of laser

technology are actually in the picture, click your mouse on the image and they will be

revealed to you…

23/4/12UP DOWN BACK

Can You See the Light?Can You See the Light?

Dentists use laser drills

Bad eyesight can be corrected by optical surgery using lasers

CD-Audio is read by a laser

Tattoo removal is done using lasers

Cd-Rom discs are read by lasers

Laser pointers can enhance

presentations Bar codes in grocery stores are scanned by lasers

Video game systems such as PlayStation 2 utilize lasers

DVD players read DVD’s using lasers

Airplanes are equipped with

laser radar

Military and Space aircraft are equipped

with laser guns

Laser tech. is used in printers, copiers, and scanners


Not to be Taken LightlyNot to be Taken LightlyThe Weighty Implications of Laser TechnologyThe Weighty Implications of Laser Technology

Click on the picture above to view the picture slide again

The previous example was meant to exemplify how the technological explosion of the last few decades has made your average day a fact of what was once thought of as wild science-fiction. As evidenced by the previous example, there are a wide array of applications of laser technology which we encounter in our daily lives. From interactive computer games to eye-sight improving surgery, laser technology has much improved the lot of mankind. Advancing technology is an integral part of mankind’s quest for improving the quality of our existence. However, as we work to refine and develop our technologies it is equally important to be aware of both the positive and negative ways in which our lives are affected.

Back toGuiding

Light


Not to be Taken LightlyNot to be Taken LightlyThe Weighty Implications of Laser TechnologyThe Weighty Implications of Laser Technology

Applications of Laser

Technology

Medical

Entertainment

Telecommunications

Military

• Optical Surgery• General Surgery• Tattoo removal

• CD Players• DVD Players• Video Game Systems

• Information tech.• Holograms

• Weapons

• Satellites

• Radar

Click on the highlighted links to learn more about the

implications of laser technology

Back toGuiding

Light Industry


The military applications of laser technology hold perhaps themost grave implications for humanity.…

The U.S.’s drive for more powerful, more accurate, and frighteningly more destructive weapons has only caused more instability within the Cold War arms control framework.

Coupled with the push towards developing weapons in space,these weapons have the potential to destroy everything, and everyone in our world.

None of which would be possible withoutLaser Technology….

Lasers & MilitaryLasers & MilitaryOminous lightsOminous lights

23/4/12UP DOWN BACK

The Reagan Star-Wars era program did much to initially support laser weapons research, resulting in many of today’s military advancements.

Lasers are used to drive fusion machines fueling thermonuclearexplosions and used in most nuclear devices.

The most potent and deadly application of laser technology is the Space Based Laser.

As tensions over the growing arsenals of nations grow, arms agreements have done little to slow down the development of these technologies.


23/4/12UP DOWN BACK

“The growing technological surge of some leading powers andtheir growing possibilities to create new-generation weaponsand military hardware are creating prerequisites for a qualitatively new stage in the arms race and a dramatic changein the forms and methods of waging hostilities.” (19)

These expensive weapons have only increased the disparity of wealth and power between underdeveloped nations and nations such as our own.


“…Although unlikely to be challenged by a global peer competitor,the United States will continue to be challenged regionally. The

globalization of the world economy will also continue, with a widening between “haves” and “have-nots.” (20)

23/4/12UP DOWN BACK

If development of these devastating applications of technology continue, the beginning of the 21st centurywill be remembered as the beginning of a new arms race --

If there is anyone left to remember it…


23/4/12UP DOWN BACK

However, laser technology has also helpedadvance the U.S. military by offering newpossibilities in warfare, such as:Non-Lethal Weapons


23/4/12UP DOWN BACK

Low energy lasers can be directed or aimed at specific targets to blind personnel or sensors either temporarily or permanently. The most advanced blinding lasers oscillate between numerous colors to make goggles and othercountermeasure ineffective.

Lasers can also be used to make a gun or otherweapon too hot to hold.

High-intensity lasers can be used in omni-directionalbombs or flares which can flash-blind personnel as well as degrade sensors and night vision devices.


23/4/12UP DOWN BACK

Factors to consider:

Is the weapon able to discriminate between the target and thecivilian population?

Does the weapon cause unnecessary suffering?

Some “non-lethal” weapons can cause temporaryor even permanent blindness.


23/4/12UP DOWN BACK

Some “non-lethal” weapons can cause temporaryor even permanent blindness.

The controversy surrounding the use of non-lethal laserscenters around whether deliberately blinding a human being causes unnecessary suffering.

Scholars in countries such as Sweden rally around the declaration of St. Peterburg which authorized the incapacitation of an opponent only for the duration of the conflict.

“Although it is permitted to kill combatants under the lawof war, and thus to put them permanently out of action, it is Not permitted to use methods or means of warfare exclusivelydesigned to injure soldiers with injuries lasting not only the duration of the conflict but for the rest of their lives.” (21)


23/4/12UP DOWN BACK

The United States disagrees with that position, reasoningthat the use of a number of conventional weapons could result in blindness.

“It is the United States’ position that lasers do not causeunnecessary suffering but are more humane because the victim is likely to suffer less injury than that caused by conventional weapons.” (21)


23/4/12UP DOWN BACK

Non-lethal weapons offer new possibilities in warfare, however the quality of life which is preserved during hostilities mustbe taken into careful consideration.

Like the “perfect” weapons of mass destruction which lasertechnology has helped to create, non-lethal weapons are notthe “perfect” war-time solution.

“Let us not hear of Generals who conquer without bloodshed.If a bloody slaughter is a horrible sight, then that is a groundfor paying more respect to War, but not for making the swordwe wear blunter and blunter by degrees from feelings of humanity, until some one steps in with one that is sharp and lops off the arm from our body.”

-Carl von Clausewitz

General Robert E. Lee emphasized another downfall toNon-lethal warfare during the Battle of Fredericksburg:

“It is well war is so terrible, or we should grow too fond of it.”


If war wasn’t as awful and grotesque as it is, it’s possiblethat it might be taken as seriously…


Although military applications of Laser Technology have such potentially devastating implications for humanity, it is easy to see that using this powerful technology to advance weaponry is a necessary evil. Without the national security that these weapons provide, our country would be vulnerable to outside attack. However, it is up to us to decide whether our vision for the future is the endless quest for military superiority, or whether our ultimate goal is peace on earth.

Back toImplications

Menu

Back toGuiding

Light

Lasers & Lasers & MilitaryMilitaryOminou Ominou ss lightslights

23/4/12UP DOWN BACK

ADVANTAGES FOR THE LASER AS A MEDICAL CUTTING TOOL

Lasers & MedicineLasers & MedicineGoing where no man has gone beforeGoing where no man has gone before

Reduces pain and trauma for the patient

Reduces pain and trauma for the patient

Speeds healing — thereby shortening costly hospital stays

Speeds healing — thereby shortening costly hospital stays

Improves the accuracy of certain surgical procedures

Improves the accuracy of certain surgical procedures

23/4/12UP DOWN BACK



• Greater accuracy of incisions

• Lasers can be inserted inside the body with little risk or discomfort

• Incisions can be guided by computers

• The laser is extremely precise, and can be tuned to work on a micro-level, barely visible to the human eye




The precision and accuracy with which lasers can cut is so exact that it would be impossible for a human to recreate. Pictured on the right is a human hair treated by an excimer laser- the cuts are so tiny that they would not be visible to the human eye! The excimer laser is typically used to perform LASIK eye surgery.

The laser as a cutting tool also has considerable industrialimplications. Click here to learn more.




• Certain conditions which were once inoperable due to the accuracy of incisions necessary are now possible.

• Today, compact lasers can be inserted inside the body with little risk or discomfort, going places and

performing surgeries that were not humanly possible before.

• Lasers guided by computers can eliminate human error in surgery.

Back toImplications

Menu

23/4/12UP DOWN BACK

Lasers & MedicineLasers & MedicineOnce i was Blind, Now i can See…Once i was Blind, Now i can See…

Laser Technology’s Contributions to Ophthalmology

Advances in laser technology have made substantial improvements in the field of ophthalmology.

Prior to these advances the solutions for those genetically pre-disposed to bad eyesight were limited:

• Glasses - which are bulky and often carry social stigma

• Contacts – which often leave eyes susceptible to infection, require

daily cleaning, and cannot be worn comfortably overnight or for extended periods of time

OR

23/4/12UP DOWN BACK


Has implications of it’s own…costly rehabilitation /treatment

loss of productivity

migraine headaches

dizzinessdriving restrictions

dependence on

eyewearimpaired ability

to read

23/4/12UP DOWN BACK


“Healthy eyesight is one of the "gold standards" of good health. As seen in Figure 1 [to the left],

86% of adults are concerned about maintaining healthy eyesight,

ranking above major fears like cancer and heart disease.

As the population ages, more and more Americans will become concerned about their eye health.”

(8)

23/4/12UP DOWN BACK


(8)

Currently, it is estimated that more than 63 million people in the U.S. are nearsighted.(8)

As the “Baby Boomer” generation ages, laser technology has and will continue to increase it’s dominance as an economic force to be reckoned with.

“The increasing number of Boomers has fueled 12% annual sales growth in reading glasses over the past 10 years, with 33.3 million adults over age 40 indicating they have purchased reading glasses.

Another growing area in the vision market is laser surgery. In 1996, surgeons performed 100,000 corrective eye surgeries.

In 1997, that figure doubled.”

23/4/12UP DOWN BACK


costly rehabilitation /treatment

loss of productivity

migraine headaches

dizzinessdriving restrictions

dependence on

eyewearimpaired ability

to read

Side vision isn't blocked, as it is with glasses.Side vision isn't blocked, as it is with glasses.

No longer the problem of dirty, wet or scratched glasses.

No longer the problem of dirty, wet or scratched glasses.

Inconvenience and discomfort of contact lenses is eliminated.

Inconvenience and discomfort of contact lenses is eliminated.

More self-confidence! More self-confidence!

23/4/12UP DOWN BACK


What is Laser Surgery?

The goal in laser eye surgery is to reshape thecornea, changing the focal point of the eye. Ideally

the focal point is changed so it focusesperfectly on the retina.

If you are nearsighted, the image comes into focus before it

hits your retina

If you are nearsighted, the image comes into focus before it

hits your retina

If you are farsighted, the image doesn’t come into

focus before it hits your retina

If you are farsighted, the image doesn’t come into

focus before it hits your retina

In a good eye the imageis focused on the retinaIn a good eye the imageis focused on the retina

((5))



How Does Laser Surgery Work?

(Picture slides & Text From (7))

After applying anesthetizingdrops, the surgeon marks theeye to indicate where the flapwill be cut and then replaced.

A suction ring holds the eyestill and pressurizes it soit is firm enough to cut.

The microkeratome slices atiny flap in the cornea.

The flap is moved out of the

way, but it is still attached. The laser removes tissue toreshape the cornea. The flap

is replaced on the eye.

Back toGuiding

Light

Back toImplications

Menu


Lasers & IndustryLasers & IndustryThe Cutting EdgeThe Cutting Edge

Laser technology has taken the jewellery industry by storm…

The superior cutting accuracy and precision which have contributed to it’s success as a medical tool are

also highly desirable for this industry.

“Laser technology, whose strengths lie in its finesse and flexibility, allows designers to create complex

geometric figures and experiment with tonal effects- indeed, different alloys can be included in the same

object, which was previously impossible at the granulation level.”

(4)

The advantages of this system over mechanical processes are substantial:

• The cuts are more precise and reduce raw material losses

• Laser welding can be automated for high-precision tasks

• The process is cleaner

• The very high cutting speed makes it possible to produce "haute couture" jewelry at industrial prices

Back toGuiding

Light

Back toImplications

Menu


Lasers & EntertainmentLasers & EntertainmentThe Light and the dark sideThe Light and the dark side

One of the most popular applications of laser technology, the Compact Disc Player, marked a revolution in digital video and sound technology.

(Pictures from (9))



Whether you’re in your car, at your computer, or running down the street, music can enhance any atmosphere and take you away from thetrials of daily life. Escaping to the movies with your home entertainment system now includes features to adapt to individual wants and needs withspecial features such as subtitles, commentary tracks, and sound options. Software is now more compactly portable due to increases in data storage capacity available on compact discs. Laser technology has made leaps and bounds in improving the quality of recorded video and sound. In additionthe increase in accessibility and portability of information and media has helped people to learn faster and be more productive. Compact Discs appear in a variety of forms, they can hold music, videos, or even computer software. The low cost of production coupled with the durability of CD’s has contributed to their becoming the standard medium for distributing large quantities of information in a reliable package at an affordable price.



Click here to learn about How a CD Works

CD’s and DVD’s

• A CD holds 783 MB on a disc that is12 cm in diameter (10)

This caters to our information-hungry generation for which knowledge equals power…

Good things come in small packages!

• A DVD has 7 times the capacity of a CD (15)

• If an average DVD movie were to be uncompressed itwould take at least a year to download over a normal

phone line. (15)

• Special DVD features such as subtitles help bridge culturalgaps and allow people from diverse backgrounds to enjoy

the same media.

• With a DVD you can skip to your favorite parts(saving time not rewinding or fast forwarding)

• Interactive CD-Rom’s are helping kids to learn fasterin school because they can go at their own pace aswell as get extra help at home using their PC’s

• The increase in memory available on CD’s has resulted inbetter quality computer and video games


Lasers & EntertainmentLasers & EntertainmentHow a CD WorksHow a CD Works

The CD Player works by using a laser beam to determine the lengths of

a series of tiny ridges inside a compact disk.

Inside a CD Player

The music is digitally encodedin the ridge lengths which are measured by the reflected laser

light. (Pictures from (10))

23/4/12UP DOWN BACK

Lasers & EntertainmentLasers & EntertainmentThe Light and The Dark SideThe Light and The Dark Side

On a local level, one of the most widespread applications of laser technology on college campuses today is the reading and writing of compact discs. This seemingly benign application has had weighty implications on the music industry and has raised controversy between artists and consumers about

the right of the people to access media.

While the ease with which digital data can be put into a disk format and then read using laser technology has made media available to a larger economic group, producers of media have been unable to control the theft and widespread distribution of electronic forms of their works.

The proliferation of recordable compact discs and CD-burners has led to this application of laser technology becoming a nemesis of the Music industry. Not only can CD’s be burned directly from one CD to another, but downloaded software from the web such as Napster and Kazaa facilitate easy downloading from a vast community of users sharing media in a base of sorts.

23/4/12UP DOWN BACK


Consequences of “Burning” Desires

23/4/12UP DOWN BACK


• The number of units shipped from record companies to retail outlets and special markets dipped 10.3 percent in 2001.

• The dollar value of the shipments dropped from US$14.3 billion in 2000 to $13.7 billion in 2001.

(Recording Industry Association of America Inc.)



"Piracy is sometimes and mistakenly called a 'victimless crime.' It is not. The economic losses due to piracy are enormous, and they are felt throughout the music value chain. Piracy also nurtures organized crime across the world, and it stunts investment, growth and jobs."

-International Federation of the PhonographicIndustry Chief Executive Jay Berman

“ While debate intensifies within the music industry over the degree of impact that peer-to-peer file sharing and CD burning has had on the global downturn in music sale new findings from international research firm Ipsos-Reid show that an estimated one-fifth (19%) of the American population aged 12 and over have downloaded music or MP3 files from an online file-sharing service (such as Morpheus, Napster, or Audio

Galaxy). This translates into over 40 million users within the current U.S. population (according to 2000 U.S. Census figures).”

(2) Back toGuiding

Light

Back toImplications

Menu

23/4/12UP DOWN BACK

Concluding ThoughtsConcluding Thoughts

As we advance towards the next century, it is inevitable that laser technologywill play an increasingly important role in society. . .

Innovation

Laser technology has already contributed to furthering the

goals of humanistic scholarship

RevolutionNew ideas and applicationsare changing our every-day

Life as we know it…

The key to managing today’s rapidly evolving technology is to constantly analyze how each advance affects us as

individuals and as a society as a whole.

23/4/12UP DOWN BACK

“Our advancing technology, if separated from the human factor, I take to be part of the advance in the evolving quality of existence, something that gives added meaning and higher dimension to the human venture…”

- Roger Sperry Neuroscientist and Nobel Laureate

23/4/12UP DOWN BACK

Types Of Laser Outputs

Business

Transcript of Types Of Laser Outputs