Laser weapons

Where’s My Laser Shark? Laser
Weapons Demystified
Nerd Nite
November 12, 2010
Olivia Koski

The Ultimate Laser Weapon
“Now all we have to do is build it.” – Real Genius (1985)
http://www.oliviakoski.com

Incoherent Versus Coherent Light
50 Watt bulb = harmless
50 Watt laser = DANGER!
Irradiance = Power / Area
Dime radius = 0.895 cm
Irradiance = 50 Watts* / p r2
Safest exposure for
1 second of green beam = 0.03 J/cm2 20 W/cm2 or 20 J/cm2 for 1 second
For a focused beam at 0.05 cm,
that’s 6,366 J/cm2
*Laser Weapon = 100,000 W OUCH!

Semiconductors Lasers
What Do You Mean By Laser?

Chemical Lasers
Free Electron Lasers
(Requires Particle Accelerator)
Jefferson Laboratory
Gas Laser (like Helium-Neon)

The chemical laser is the most
powerful laser weapon
Solid state lasers weapons are
more compact but less powerful
than chemical laser weapons
Textron
Northrop Grumman

Some Quick Laser Physics
E = mc2
DE = hn = hc/l
h = Plank’s constant
v = frequency
l= wavelength
c = the speed of light
DE = hn

How to Build a Laser
LASER = Light Amplification through Stimulated Emission Radiation
Get a laser rod (your gain medium)
Add pump powerPut on your laser
goggles
Put mirrors around itPut mirrors around it

The Real Genius Popcorn Fantasy

The Multi-Billion Dollar Reality

The Real-life Missile Shoot Down
The Airborne Laser Shot down a missile on February 11, 2010 off the coast of California

A Flaw in the Laser Science of Real Genius
The real Airborne Laser is actually invisible (1315 nm)

Ray Guns versus Light Sabers
When was the last time soldiers had a sword fight?
Soldiers still shoot at each other all the time.

An Elegant Weapon For A More Civilized Age?
“Not as clumsy or random as a blaster.”
Obi-Wan Kenobi

A laser makes a much better gun than a sword.
Just saying.
But there are still major flaws in the laser science of Star Wars:
silly noises and random visible wavelengths

The U.S. Air Force Built a Non-Lethal Laser Gun
Personnel Halting and Stimulation
Response Rifle (PHaSR)
Low power Infrared and Visible lasers
It will not hurt you, but it will startle
you temporarily
“PHaSR, or Personnel Halting and Stimulation Response, is a rifle sized
counter personnel nonlethal laser weapon system. PHaSR achieves the
desired degree of protection through the synergistic application of two
non-lethal laser wavelengths during the course of protection activities
that will deter, prevent, or mitigate an adversary’s effectiveness. The
laser light from PHaSR temporarily impairs aggressors by “dazzling”
them with one wavelength. The second wavelength causes a repel
effect that discourages advancing aggressors.” –U.S. Air Force

This is not an elegant weapon for a more civilized age
1 Watt 445 nm made by
Wicked Laser - $300
But it can hurt you!
Especially your eyes – wear goggles!
No plans to issue these to soldiers any time soon.
It’s a novelty.

Okay, so what about those laser sharks?

Seriously, It Wouldn’t Be That Difficult.
http://www.flickr.com/photos/the-lees/134610871/in/photostream/
500 mW green laser for $2000
1. Buy a green laser
2. Design a head piece
3. Hire a trained professional to attach it to the shark*
* I don’t actually recommend doing this but it is
technically quite possible http://www.oliviakoski.com

How Well Would The Shark’s Laser Move
Through Water?
Hot air makes giraffes look all wonky because
it acts like a bunch of little tiny lenses.
FACT: Light interacts with matter
Water absorbs light
green ~ 510 nm
High Absorption
Low Absorption
Green is not a bad choice
for a shark laser

But Lasers Are Perfect For Space
There is less pesky matter in space to mess up your laser

Lasers In Space, Underwater, or In the Air Are
Still Dangerous To Your Eyes
Always wear your goggles!
Danger Zone
400 nm 1400 nm
Light penetrates eyeball,
can damage the retina
light is absorbed
by cornea, lens
light is absorbed
by cornea, lens

The Most Important Thing About A Laser Weapon
Is Power On Target
It’s all about
Beam
Quality
Good Laser
Bad Laser
Bad Laser

This Is What Happens When BQ Is Good
Boeing’s Advanced Tactical Laser lights the hood of a truck on fire

Why Laser Weapons Are Like Ninjas
Invisible
Silent
Deadly

Thanks!
Learn About 3D Printing:
http://www.makerbot.com
Follow me on twitter:
http://twitter.com/oliviakoski
Find out what Nerds in New York do
from the Urban Scientist:
http://www.scienceline.org/
A special thanks to all of the Laser Safety Officers out there and all of
my colleagues and friends in Boulder, Boston, and Sunnyvale

Eye damage
• 180–315 nm (UV-B, UV-C) photokeratitis (inflammation
of the cornea, equivalent to sunburn)
• 315–400 nm (UV-A) photochemical cataract (clouding
of the eye lens)
• 400–780 nm (visible) photochemical damage to the
retina, retinal burn
• 780–1400 nm (near-IR) cataract, retinal burn
• 1.4–3.0μm (IR) aqueous flare (protein in the aqueous
humour), cataract, corneal burn
• 3.0 μm–1 mm corneal burn
http://en.wikipedia.org/wiki/Laser_safety

Maximum permissable exposure as a function of wavelength
http://en.wikipedia.org/wiki/File:IEC60825_MPE_J_s.png

Laser weapons

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