>Psychtoolbox>PsychRadiometric>PsychAnsiZ136MPE

Psychtoolbox:PsychAnsiZ136MPE.

Partial and in progress implementation of Ansi Z136.1-2007 standard for computing
maximum permissable exposure.

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IMPORTANT:
a) Individuals using these routines must accept full responsibility
for light exposures they implement. We recommend that values computed
with these routines be carefully checked against independent calculations.
We have done our best to follow the standard, but it is very complex and
there may be errors.

b) There is now (Jan 2015) an updated version of this standard that is more
conservative. Thus these routines are now mainly for historical
reference. We would love it if someone were to provide a Matlab
implementation of the new standard.

b) As of March, 2013, these routines are still very much a work
in progress and should thus be treated with special caution. See
AnsiZ136MPEBasicTest and AnsiZ136MPEDeloriTest, both for test
code, and for comments about points of uncertainty.

c) Particularly obscure to me at present is the limiting cone aperture
section described with an asterisk in Table 2 of the 2007 standard
document.

d) The field’s knowledge of safe light levels is evolving, and it is important
to keep abreast of current research and not to rely soley on the
Ansi standard. In particular, note that there
are reports of disrubption at light levels below the limits specified
in the Ansi 2007 stanard. See for example:
Morgan et al., (2008), IOVS, 49, 3715-3729.
Morgan et al., (2009), IOVS, 50, 6015-6022.
Hunter et al., (2012), Prog. Ret. Eye. Res., 31, 28-42.

e) Apparently a new version of the Ansi Z136 standard is forthcoming,
but I do not have information as to what changed.

f) The Z136 standard is for laser light, which is coherent and monochromatic.
Different standards apply for broadband lights. Two relevant references are:
ISO 15004-2:2007, Ophthalmic instruments – Fundamental requirements and
test methods – Part 2: Light hazard protection.

ICNIRP (International Commission on Non-Ionizing Radiation Protection) Guidelines,  
(1997), Guidelines on exposure to broad-band inchoherent optical radiation (0.38 to 3 uM),  
Health Physics, 73, 539-554.     The second seems a little old, but is the most recent ICNIRP guideline for broadband     that I could easily locate.  

• David Brainard, March 6, 2013.
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REFERENCES.
Ansi Z136.1-2007. The standard document. The more recent Ansi Z136.8-2012
refers back to the 2007 document for the MPE calculations. But see
point d) in the notes above.

Delori et al., 2007, JOSA A, 24, 1250-1265. Provides explanation
about many of the calculations in the 2000 version of the standard.

AnsiZ136MPEBasicTest - Test the suite of routines. Generates many figures that should match those in the standard.
AnsiZ136MPEComputeCa - Compute constant Ca, Table 6
AnsiZ136MPEComputeCb - Compute constant Cb, Table 6
AnsiZ136MPEComputeCc - Compute constant Cc, Table 6
AnsiZ136MPEComputeCe - Compute constant Ce, Table 6
AnsiZ136MPEComputeExtendedSourceLimit - Compute overall MPE limit for extended sources, Table 5b
AnsiZ136MPEComputeExtendedSourcePhotochemicalLimit - Compute photochemical MPE for extended sources, Table 5b
AnsiZ136MPEComputeLimitingConeAngle - Compute limiting cone angle, Table 6
AnsiZ136MPEComputeT2 - Compute constant T2, Table 6
AnsiZ136MPEDeloriTest - Tests our computations against those from Delori’s spreadsheet.