NANO-STRUCTURED OPTICAL FILTERS FOR LASER SAFETY - George Palikaras, Themos Kallos, LamdaGuard Ltd. Nano-technology film developed which is optically transparent but filters out multiple lasers Flexible film sticks inside the windscreen, visor or goggles/glasses Threat from 5mw laser which is eye hazard at 16 m Threat of 1000mw laser - eye hazard at 80m Existing solutions filter just single wavelength This Metamaterial film used to make an optical filter is another potential solution Specified light at a single wavelength is turned into heat from light Patent applied-for solution first prototype has been developed Q1 in 2012 ‘Lambda Guard’ aims to prevent laser interference altogether Filters applied to Aircraft cockpit windscreens, Police helmet visors, Police shields etc.

2. 2008

3. Risks & Hazards

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Courtesy: www.laserpointersafety.com

5. 90000
Forecast
80000
Reported Incidents
70000
60000
50000 UK
US
40000 EU
World
30000
20000
10000
0
2007 2008 2009 2010 2011 2012 2013 2014 2015
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6. Beam size: A laser's beam spreads out. At
long ranges the beam can be many inches or
even feet in diameter. When laser light hits an
aircraft's windscreen, tiny scratches and dirt
spread the light out even more, causing glare
around the beam center. The result is that
pilots do not see a small dot, they see a
large glow similar to being in a flashlight or
searchlight beam. It can be difficult or
impossible to see through the glow.
Beam flashes: It is hard to hand-hold a
laser on a moving target that is far away.
That's why in most laser pointer incidents,
pilots don't see a steady light on them.
Instead, they see one or more flashes.
The flashes are distracting at best, and at
worse, they can be bright enough to
cause temporary flashblindness.
Example: This is similar to having a camera
Courtesy: www.laserpointersafety.com flash (or flashes) go off in your face

7. Eye injury: Though it is unlikely, high power
visible or invisible (infrared, ultraviolet)
laser light could cause permanent eye
injury. The injury could be relatively minor,
such as spots only detectable by medical exam
or on the periphery of vision.
Pilots are not expecting bright lights during
landings, their eyes are exposed to potential
illuminations by powerful laser beams.
Courtesy: www.laserpointersafety.com

8. Visual Hazard Distances for 532nm (green) pointer lasers
Power Max flash Max glare/ Max
Sqrt of Max eye
Increase blindness disruption distraction
Laser Power power hazard
(compared hazard hazard hazard
increase distance
to 5mW) distance distance distance
5 mW x1 1.0 16 m 80 m 366 m 3560 m
50 mW x10 3.2 50 m 250 m 1156 m 11276 m
125 mW x25 5.0 79 m 396 m 1829 m 17830 m
250 mW x50 7.1 112 m 560 m 2586 m 25216 m
500 mW x100 10 160 m 800 m 3660 m 35600 m
1000 mW (1W) x200 14.1 320 m 1600 m 7320 m 71200 m
Distraction Glare/Disruption Flash blindness
A solution needs to attenuate power ~20 times
Patrick Murphy, Lasers & Aviation Safety, International Laser Display Allocation, Sep 2010

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Array of 24 Blue Lasers
Courtesy: frigginSmift via youtube.com

10. FACT: Laser protective FACT: It is likely that many pilots would go
goggles and glasses must be through their entire career without ever
on before exposure to the encountering laser interference so wearing
laser. They operate at a goggles against lasers is a less attractive
broad spectrum not at the solution
laser wavelengths only

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Pendry, Metamaterial Congress 2008; www.news.iastate.edu; http://www.metaphotonics.de

13. λ λ
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λ λ

14. Positive Index η>0 Negative Index η<0
Concept

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Maier & Atwater, JOURNAL OF APPLIED PHYSICS 98, 011101 2005

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Microwave 1cm
Filter!
200 nm
Z. Liu et al., Science 315, 5818 (March 23, 2007).

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• ε

19. Developing an optimal solution:
Metamaterial
Nano-particles

20. Nano-particle
Metamaterial Array
Unit cell Cross-section Fields on surface
100x
zoom
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•
α
ε
ε

21. In-house Computational Capability
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•
www.cst.com

22. Fields on surface Cross-section of electric field at resonant
frequency (λ=500 nm)
•

23. @ 332.9778 nm (900.9611 THz)
30
20
 m=1.0
 m=1.5
•
 m=1.7
10
 m=3.0
Im( )
0
 m=1.0
 m=1.5 -10 ε
 m=1.7
-20
 m=3.0
-30
00 400 600 800 1000 200 400 600 800 1000
Wavelength [nm] Wavelength [nm]
1
D=10 nm
D=20 nm •
0.8
21
Amplitude S
0.6
0.4
D=10 nm
0.2 D=20 nm
0
00 800 1000 1200 600 800 1000 1200
Frequency [THz] Frequency [THz]
Kallos et al., PHYSICAL REVIEW B 84, 045102 (2011); Kallos et al., RADIO SCIENCE, VOL. 46, RS0E06

24. Proposed use in Civil Aviation

25. Protective Layer
[Inside cockpit]
Metamaterial
Adhesive layer
Cockpit Glass
10x [Outside]
Laser Lights Blocked: Nano-particle
30 zoom Nano-particle
 m=1.0
20  m=1.5 Metamaterial Array
 m=1.7
10
 m=3.0
Im( )
0
-10
100x
zoom
-20
-30
200 400 600 800 1000
Wavelength [nm]

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First Prototypes in Q1, 2012

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30. LAMDA GUARD LTD.
London, UK
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Prof. Clive Parini Prof. Pandurang Ashrit Prof. Filipe Chibante
Director of Antenna & Director of Thin Films and Head of Nano-Composites
Electromagnetics Research Group Photonics Research Group Engineering Research Group

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Kallos et al., RADIO SCIENCE, VOL. 46, RS0E06, (2011)

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Kallos et al., PHYSICAL REVIEW A 79, 063825 2009; Zhang et al., PRL 106, 033901 (2011);

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• Δλ
T. Scharf, Polarized Light in Liquid Crystals and Polymers; http://en.wikipedia.org/wiki/Distributed_Bragg_reflector

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T. Scharf, Polarized Light in Liquid Crystals and Polymers; TyrionL (Own work) [Public domain], via Wikimedia Commons

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Hwang et al., nature materials | VOL 4 | MAY 2005

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Polarized Light in Liquid Crystals and Polymers; Ha et al., Nature Materials, vol.7, pp.43-47 (2008)

38. Microwave negative index metamaterial Schematic diagram for light bending metamaterial,
at 1.5 micrometre wavelength. Courtesy of G.
Dolling et al., Opt. Lett. 31, 1800 (2006)
•
λ λ
• λ
• λ
•
http://en.wikipedia.org/wiki/Split-ring_resonator; Shelby, R. A.; Smith D.R.; Shultz S.; Nemat-Nasser S.C. (2001). "Microwave
transmission through a two-dimensional, isotropic, left-handed metamaterial". Applied Physics Letters 78 (4): 489