EL for Broadband Optical Radiation Karl Schulmeister ICNIRP SC-IV Member Seibersdorf Laboratories, Austria

ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

100 nm ~400 nm 780 nm 1 mm UV vis IR

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Exposure Limits

•UV –s()

• UV-A

• Retina photochemical • Retina thermal

•Infraredeye

• Skin (vis. and IR)

Photographs courtesy of P Söderberg JP Cesarini and Univ. Michigan, Kellogg Eye Center

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Exposure Limits

•UV –s()

• UV-A

• Retina photochemical • Retina thermal

• Infrared eye

• Skin (vis. and IR)

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Current Guidelines: ICNIRP Guidelines on limits of exposure to broad-band incoherent optical radiation (0.38-3µm) Health Phys. 73: 539-554; 1997

New Edition of Guidelines for visible and IR:

Open Consultation 2011 Health Physics Publication: End 2012/Beginning 2013

Product Standards updated in parallel: CIES009/ IEC 62471 (Lamp Product Safety Standard) IEC 60825-1 (Laser Product Safety Standard)

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Absorption location and mechanism overview

•UV-C, B

•UV-A P H O T O-

•vis C H E M I C A L E = h * 

•IR-A

•IR-B, C T H E R M A L

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Changes in Guidelines . Thermally induced retinal injury

. Near IR limit for cornea/lens

No changes: .photochemically induced retinal injury „blue light hazard“ (but averaging FOV defined for t > 100 s) .UV .skin

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Current EL - retinal thermal injury

Effective Exposure Exposure Limit

10.25  2  1  L RtkWmsr()  50   in rad! For t < 10 s – Wavelength dependence

– Base limit value

– Retinal spot size dependence

– Pulse duration dependence

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 R() Wavelength Dependence

10 Thermal Current 1

0.1

Thermal New 0.01 Action Spectrum (rel.) Spectrum Action 400 600 800 1000 1200 1400 Lund DJ, BE Stuck, P Edsall Wavelength (nm) Retinal injury thresholds for blue wavelength lasers Health Phys 90: 477-484; 2006

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 R() Wavelength Dependence

10 1.0 Thermal Current 1

0.5

0.1

Relative injury threshold Relative injury 400 500 600 700 Wavelength [nm] Thermal New 0.01 Action Spectrum (rel.) Spectrum Action 400 600 800 1000 1200 1400 Lund DJ, BE Stuck, P Edsall Wavelength (nm) Retinal injury thresholds for blue wavelength lasers Health Phys 90: 477-484; 2006

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

] Sun -1 105 weighted, current nm -1 sr -2 Unweighted 104

103 weighted, new

Spectral Radiance [W m Spectral Radiance [W 102 400 600 800 1000 1200 Wavelength [nm]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

] Sun -1 105 weighted, current nm -1 sr -2 Unweighted 104

103 weighted, new

7 W m-2 sr-1 eff. Spectral Radiance [W m Spectral Radiance [W 102 400 600 800 1000 1200 Wavelength [nm]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

] Sun -1 105 weighted, current nm -1 -2 -1

sr 16 W m sr eff. -2 Unweighted 104

103 weighted, new

7 W m-2 sr-1 eff. Spectral Radiance [W m Spectral Radiance [W 102 400 600 800 1000 1200 Wavelength [nm]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Wavelength Evaluation Less Restrictive 3.5

3.0

2.5

2.0 ite Wh 1.5 ld Co

Old/New Effective Radiance 1.0 1000e 2000 3000 4000 5000 6000 7000 hit W Colour Temperature [Kelvin] rm Wa

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Current EL - retinal thermal injury Radiance Effective Exposure Exposure Limit

10.25  2  1  L RtkWmsr()  50   in rad! For t < 10 s – Wavelength dependence

– Base limit value

– Retinal spot size dependence

– Pulse duration dependence

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Angular Subtense of Source & Image Diameter  []rad  Distance

 

Sun:  = 0.01 rad Image: 170 µm

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Solid Angle of Source & Image Area []sr Distance2

   []sr  2 4

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012  W  Irradiance W m2  Radiance 2  m sr Solid Angle[] sr W/m2

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

WW Ret.Irrad.Tsr Radiance  Solid Angle Pupil[ ] 22 mmsr

W/m2

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Properties of Radiance . Does not depend on distance



Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Properties of Radiance . Is not changed by optical intruments

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Telescope: 7 Magn. Image: 1.2 mm 50 mm Optics Diam. 72 x Irr. x 

 Same ret. irradiance!

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Spot Size Dependence Retinal diameter [µm] 110100 ] -2

 -2 a) 1000 d e p .

100   d e

min p en max  de  nc 10 e no  dep. Retinal radiant exposure [units: J m Retinal radiant exposure 110100  [mrad]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Retinal diameter [µm] Retinal diamete r [µm] 110100 1 10 100 100

. p  b) e -2 a) d 2 1000 d

] e  p

10 -2 .

ce 100   n 1 de d

min e max

n min p max [units: µJ] [units: e e   p m [units: J n e  d de   n ce no  dep. 10 no  dep.

0,1 Retinal radiant exposure Total Intraocular Energy Total Intraocular 110100 1 10 100  [mrad]  [mrad] Radiance = Retinal Irradiance Solid Angle of Pupil

Retinal Irradiance = IOP/Image Area

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Larger Spot: Compromised Cooling 50 100 ms 1000 µm Temperature rise 100 µm 40 after 100 ms

10 Temperature difference [K] difference Temperature 0

-1000 -800 -600 -400 -200 0 200 400 600 800 1000 Radius [µm] For same retinal irradiance, larger spot higher temperature

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Larger Spot: Compromised Cooling 50 100 ms 1000 µm Temperature rise 100 µm 40 after 100 ms

30 Injury when critical temperature is exceeded →→ LargerLarger spotsspots havehave lowerlower20 injuryinjury thresholdthreshold

10 Temperature difference [K] difference Temperature 0

-1000 -800 -600 -400 -200 0 200 400 600 800 1000 Radius [µm] For same retinal irradiance, larger spot higher temperature

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Spot Size Dependence Retinal diameter [µm] 110100 ] -2

 -2 a) 1000 d e p .

100   d e

min p en max  de  Current: nc 10 e no  dep. max = 100 mrad 1.7 mm @ retina Retinal radiant exposure [units: J m Retinal radiant exposure 110100  [mrad]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Spot Size Study

. 532 nm (green), 1090 nm (IR) . Pulse durations 100 µs to 2 s . Spot Size: 20 µm to 2 mm

532 nm: 31 thresholds 170 samples 5000 exposures

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Spot Size Dependence

1000 ] -2 100 ] -2

2 s 1000 -2 655 ms  dep.

10 100 ms 100 min max 

10 ms    10  dependence no dep. Retina radiantexposurem J [units: 1 1 ms Radiant Exposure [J cm Radiant Exposure 110100  [mrad]

0.1 ms Diffusion length = 2 √(Dth t) 0,1 10 100 1000 Diameter [µm] Ex-vivo and computer model study on retinal thermal laser induced damage in the visible wavelength range K Schulmeister, et al J. Biomed. Optics 13, 054038 (2008)

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Impact of radial cooling 50 45 100 ms pulse duration 40 35 30 25 D = 1.6 mm 20 D = 400 µm 15 D = 200 µm D = 1.0 mm 10 D = 800 µm D = 100 µm Temperature rise [K] 5 0 -2000 -1000 0 1000 2000 Radius [µm]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

max . Retinal spot so large, that (during pulse), center is not affected by „cooling wave“

. Thermal diffusion length = 2 √(Dth t)

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

max depends on t •The longer pulse duration  • the more time the cooling wave has to reach the center, • the larger image has to be so that center is not cooled within 

• Diffusion length = 2 √(Dth )

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Time dependent max 0.5 max = 200 t 100 mrad @ 0.25 s 100 (for 625 µs < t < 0.25 s)

max = 5 mrad for t < 625 µs 10 max = 100 mrad for t > 0.25 s alpha-max [mrad] 5 mrad @ 0.6 ms

(currently = 100 mrad for all t) 1 1E-6 1E-5 1E-4 1E-3 0.01 0.1 1 10 Pulse duration [s]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

101 10 ms 1 ms

101

100

10-1 MPE MPE Radiant exposure [J/cm²] -1 Radiant exposure [J/cm²] 10 10-2 10 100 1000 10 100 1000 Retinal diameter [µm] Retinal diameter [µm]

Maximum increase from change of max: factor 20

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Time Dependence

Raise of limit due to time dependent max → lower base limit 10.25 2 1 LtkWmsreff  20  10 7 mm

Plot applicable for  < max Pupil

c ur re nt

Factorfactor 2,5 2.5 BUT: keep it constant

Exposure Limit (relative) Exposure Limit for t > 0.25 s new 1 (pupil constriction) 0.25 s 0.001 0.01 0.1 1 10 Pulse Duration [s] Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Time Dependence

Raise of limit due to time dependent max → lower base limit 10.25 2 1 LtkWmsreff  20  10 Decrease 2.5 Plot applicable for  <  max (Basic Limit)

c ur re Increase x 20 for > 100 mrad nt

pulsed sources Factorfactor 2,5 2.5 Net-Increase for large

Exposure Limit (relative) Exposure Limit pulsed sources: new 1 Factor 8 0.25 s 0.001 0.01 0.1 1 10 Pulse Duration [s] Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Time Dependence

Raise of limit due to time dependent max → lower base limit 10.25 2 1 LtkWmsreff  20  10

Plot applicable for  < max For continous sources, c 0.25 s exposure duration: ur re nt Reduction factor 2.5

Factorfactor 2,5 2.5 Exposure Limit (relative) Exposure Limit new 1 0.25 s 0.001 0.01 0.1 1 10 Pulse Duration [s] Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Wavelength Evaluation Less Restrictive 3.5

3.0

2.5

2.0 ite Wh 1.5 ld Co

Old/New Effective Radiance 1.0 1000e 2000 3000 4000 5000 6000 7000 hit W Colour Temperature [Kelvin] rm Wa

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Sun

. Effective Radiance: 7 MW m-2 sr-1

. EL for 0.25 s: 3 MW m-2 sr-1 (7 mm Pupil)

. „Safe“ Pupil: 4.5 mm

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Relevance . Flashlights, pulsed LEDs

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Photoflash . regular photoflash for semi-professional cameras

1800

1600 ] -1 1400 nm -2 1200

1000

800

600

400 Radiant exposure [mJ m [mJ exposure Radiant 200

0 300 400 500 600 700 800 900 1000 Wavelength [nm] Pulse duration 2 ms

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

-1 -2 -1 t < 1 µs: Deff ≤ 0.6  J m sr

D… Time integrated radiance (L·t)

10.25  2  1 1 µs < t < 0.25 s: LtkWmsreff  20 

-1 -2 -1 t > 0.25 s: Leff ≤ 28  kW m sr

Averaging FOV th: cw: 11 mrad; Pulsed (t < 0.25 s): 5 mrad

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

1000 Decrease 2.5 ] -1 (Basic Limit)

sr  -2 m 100 a = x 5 m rad Increase 20 (max) 10 20 x  =  (t) max Net-Increase: 1 Factor 8 max = 100 mrad Radiance [MW m Radiance [MW 0,1 1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 Pulse Duration [s]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Multiple Pulses

 ≤ 5 mrad: C5 = 1

-0,25  > 5 mrad: C5 = N with following max N numbers (max reductions):

 ≤ max: max-C5 = 0.4 (max-N = 40)

 > max: max-C5 = 0.2 (max-N = 625)

 > 100 mrad: C5 = 1

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

Summary 10 Thermal Current up to – Wavelength dependence 1 Factor 2-3

0.1

Thermal New – Retinal spot size dependence 0.01 Action Spectrum (rel.) – Pulse duration dependence 400 600 800 1000 1200 1400 Wavelength (nm)

10 101 1 ms

c 100 Up to ur re nt

Factor 20 factor 2,5 Factor 2.5 10-1

MPE Radiant exposure [J/cm²] Exposure Limit (relative) new 1 10-2 0.25 s 0.25 10 100 1000 0.001 0.01 0.1 1 10 Retinal diameter [µm] Pulse Duration [s]

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Low Visual Stimulus

Luminance < 10 cd m-2

1400 10.25  2  1  L RtkWmsrsts() 20 (0.25  810)100 s) 780

1400 121  L RkWmsr( )  6000 (for t 100 810 s) s ) 780

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Low Visual Stimulus

c ur re nt

factor 2,5 Exposure Limit (relative) Exposure new 1

0.25 s 100 s 0.001 0.01 0.1 1 10 Pulse Duration [s]

6000 -1 Wm-2 sr-1

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 Photochemical Retinal

J D ≤ 106 B m² sr Solid angle (sr) Area (m²) 10 s < t < 10 000 s (Basic Limit)

Averaging Field of View ph „Small source limit“ -4 < 100 s ph = 11 mrad  = 10 sr 100 J/m² -6 100 s – 10 000s ph = 1.1√t mrad  = 10 ·t sr 1 W/m² -2 t > 10 000 s ph = 110 mrad  = 10 sr 1 W/m²

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012 IR-Limit Cornea/Lens

1000 3000 „Action Spectrum“ EEEIR 0.5   780 1000

0.75 2 EIR 18tkWmforts (  1 000 ) t ≥ 1000 s: 100 W m-2 (10 mW cm-2) High Irradiance Pulses: Long Term Chronic: (Glass blowers cataract)

Laser on Rabbit eye

courtesy of Tsutomu Okuno

Broadband Optical Radiation Karl Schulmeister ICNIRP 7th International NIR Workshop Edinburgh, United Kingdom, 9-11 May 2012

ThankThank YouYou

Broadband Optical Radiation Karl Schulmeister