Alfredo Dubra's PhD thesis - Imperial College London

Appendix B
Laser safety calculations
In all the experiments conducted for this thesis, the maximum permissible exposures
(MPEs) of the human eye to electromagnetic radiation were calculated based on the
British and European standard Safety of laser products (BS EN 60825-1:1994 with
amendments 1, 2 and 3). The MPE calculations below will only consider retinal
thermal damage as the cornea, aqueous humor, lens and vitreous humor are considered
transparent for all the wavelengths of the sources used in the experiments (i.e. within
the range 600 − 1400nm).
apparent
source
a
eye
r
Figure B.1: Definition of subtended angle α by an apparent source at a distance r.
The diameter of the pupil of the eye applicable to measuring laser irradiance exposure
for a wavelength between 400 and 1400 nm is 7 mm for t < 3 × 10 4 s, thus, the area of
the pupil to be considered is
A pupil ≈ 4 × 10 −5 m 2 .
(B.1)
123