The accessible emission limits (AEL) for the retinal thermal hazard as specified in the international standard series IEC 62471 for photobiological safety of lamps and lamp systems depends on the angular subtense of the apparent source α. No method is specified how to determine α for complex sources such as LED arrays or image projectors. Currently, the peak radiance has to be compared against the AEL determined with largest value of α that can be associated to the apparent source, often leading to overly restrictive results. A method was developed for determining the size of the apparent source and permitting averaging radiance over a certain field of view, with the aim of producing appropriate safety margins for any possible irradiance profile. It was validated against more than 250 exposure scenarios by means of a computer model for laser-induced retinal injury to ensure that the injury threshold level is in no instance lower than 1.5 times the AEL. The proposed method for complex apparent sources is up to 10 times less conservative than using the outer edge for the determination of α and the peak radiance.

1.
Söderberg
P.
,
Stuck
B.E.
 et al (
2013
)
ICNIRP Guidelines on limits of exposure to incoherent visible and infrared radiation
,
Health Phys
105
:
1
.
https://doi.org/10.1097/HP.0b013e3182983a22
Google Scholar
Crossref
Search ADS
PubMed
 
2.
European Parliament and the Council
(
2006
) Directive 2006/25/EC on artificial optical radiation.
3.
International Electrotechnical Commission
(
2013
) IEC 62471-1 draft for comments, IEC document 76/495/DC.
4.
International Electrotechnical Commission
(
2014
) IEC 62471-5 Ed. 1.0 Photobiological safety of lamp systems. Part 5 Image projectors, IEC document 76/504/CDV.
5.
Schulmeister
K.
 (
2005
)
The ‘Apparent Source’ – A Multiple Misnomer
, Conf. Proc. of ILSC,
91
–
98
.
Google Scholar
 
6.
Henderson
R.
 &
Schulmeister
K.
 (
2004
)
Laser Safety
,
Taylor & Francis Group
:
New York, London
.
Google Scholar
Crossref
Search ADS
 
7.
Schulmeister
Κ.
,
Stuck
B.E.
 et al (
2011
)
Review of thresholds and recommendations for revised exposure limits for laser and optical radiation for thermally induced retinal injury
,
Health Phys
100
:
2
.
https://doi.org/10.1097/HP.0b013e3181ea51e3
Google Scholar
Crossref
Search ADS
PubMed
 
8.
Schulmeister
K.
 (
2010
)
Present and alternative dosimetry concept for laser exposure limits
,
Med Laser Appl
25
.
Google Scholar
 
9.
Schulmeister
K.
 (
2013
) The radiance of the sun, a 1 mW laser pointer and a phosphor emitter,
Conf. Proc. of ILSC
, paper #107.
10.
International Electrotechnical Commission
(
2014
) IEC 60825-1 Ed. 3.0: Safety of laser products – Part 1: Equipment classification and requirements.
11.
Jean
M
 &
Schulmeister
K.
 (
2013
)
Validation of a computer model to predict laser induced thermal injury thresholds of the retina
,
Conf. Proc. of ILSC
, paper #1002.
Google Scholar
Crossref
Search ADS
 
12.
Lund
D.J.
,
Edsall
P.
 &
Stuck
B.E.
 (
2001
)
Ocular hazards of Q-switched blue wavelength lasers
,
Proc. of SPIE
4246
,
44
–
53
.
https://doi.org/10.1117/12.426722
Google Scholar
Crossref
Search ADS
 
13.
Atchison
D.A.
 &
Smith
G.
 (
2000
)
Optics of the Human Eye
,
Butterworth-Heinemann
:
Edinburgh
.
Google Scholar
 
14.
Sliney
D.H.
,
Mellerio
J.
 et al (
2002
)
What is the meaning of threshold in laser injury experiments?
Health Phys
82
:
3
.
https://doi.org/10.1097/00004032-200203000-00006
Google Scholar
Crossref
Search ADS
 
15.
Stuck
B.E.
 (
1984
)
Ocular susceptibility to laser radiation: human vs. rhesus monkey, Chapter 4 in Handbook of laser bioeffects assessment – volume 1 – Bioeffects data
,
Letterman Army Institute of Research
,
San Francisco CA
.
Google Scholar
 
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