Instructions

HD2402 - 29 - V1.3
If the preceding limit is not exceeded, t_100 will be above 10000s; if this is be-
low, the succeeding limit will have to be taken into consideration.
o L
B
(11mrad) [W/(m² sr)] radiance calculated assuming that all light comes from
a circular area whose angular dimension is 11mrad.
This is true if the observation time is above 10s and below 100s; in fact, for time
periods within this interval the smallest source detected by the human eye is
11mrad (CEI IEC 62471).
If value L
B_11
<= 10000 [W/(m² sr)], the limit is not exceeded and the other lim-
its have to be taken into consideration. The source belongs to risk class 1.
If L
B_11
> 10000 [W/(m² sr)], the limit is exceeded and it is necessary to take in-
to consideration the succeeding limit (the observation time is below 100s, so
even the minimum angular dimension that can be focused by the human eye be-
comes smaller, the succeeding limit is that with an angle of 1.7mrad).
o t_11 [s] time period during which the source can be observed without damages
to the visual system.
If the preceding limit is not exceeded, t_11 will be above 10s; if this is below,
the succeeding limit will have to be taken into consideration.
o L
B
(1.7mrad) [W/(m² sr)] radiance calculated assuming that all light comes from
a circular area whose angular dimension is 1.7mrad.
This is true if the observation time is below 0.25s (CEI IEC 62471).
If value L
B_1.7
< 4
•
10
6
[W/(m² sr)], the limit is not exceeded. The source belongs
to risk class 2.
In any case, the maximum exposure time can be calculated, that will always be
below 0.25s.
o t_1.7 [s] t time period during which the source can be observed without dam-
ages to the visual system, calculated from t_1.7=10
6
/L
B_11
.
• Alpha [rad] , the user supplies the angular dimension of the source in radiants or
degrees:
o Alpha [rad] angle subtended by the source in radiants or degrees.
o Omega [sr] solid angle subtended by the source, calculated starting from Alpha
angle assuming that the source shape is circular:
Omega = 2π (1-cos(Alpha/2))
o L
B
(100mrad) [W/(m² sr)] radiance calculated assuming that the source has an
angular dimension of 100mrad.
o L
B
(11mrad) [W/(m² sr)] radiance calculated assuming that the source has an
angular dimension of 11mrad.
o L
B
(1.7mrad) [W/(m² sr)] radiance calculated assuming that the source has an
angular dimension of 1.7mrad.
o L
B
(real) [W/(m² sr)] is the real radiance calculated starting from the entered
geometric parameters.