Instructions

HD2402 - 41 - V1.3
Note: Alpha_1 and Alpha_2 values are those perceived by the visual system and
are calculated starting from α_1, α_2 angles calculated uniquely from geometric pa-
rameters.
α_1, α_2 Alpha_1 Alpha_2
α_1>100, α_1>100 2 x Tan
-1
(d1/2R) 2 x Tan
-1
(d2/2R)
11≤α_1≤100, α_2>100 2 x Tan
-1
(d1/2R) 100mrad
11>α_1, α_2>100 11mrad 100mrad
11>α_1, 11≤α_2≤100 11mrad 2 x Tan
-1
(d2/2R)
11≤α_1≤100, 11≤α_2≤100 2 x Tan
-1
(d1/2R) 2 x Tan
-1
(d2/2R)
α_1>100, 11<α_2<100 100mrad 2 x Tan
-1
(d2/2R)
11>α_1, 11>α_2 11mrad 11mrad
11<α_1<100, 11>α_2 2 x Tan
-1
(d1/2R) 11mrad
α_1>100, 11>α_2 100mrad 11mrad
o Alpha [rad] average angle subtended by the source calculated as the average of
Alpha_1 e Alpha_2. This angle must be known to be able to calculate the real ra-
diance perceived by human eye (CEI IEC 62471).
o Omega [sr] solid angle under which the rectangle is seen. Calculation can be per-
formed rigorously or approximately.
o L
B
(100mrad) [W/(m² sr)] radiance calculated assuming that the source angular
dimension is 100mrad.
o L
R
(11mrad) [W/(m² sr)] radiance calculated assuming that the source angular
dimension is 11mrad.
o L
R
(real) [W/(m² sr)] real radiance calculated starting from the entered geomet-
ric parameters.
o t_lim [s] exposure time limit, that is the time period during which a source can
be observed without damages to the visual system. This value is calculated with
the following procedure:
if Alpha > 100mrad it is assumed that C
α
= 100
if L
R_real
≤ 6
•
10
4
⇒ t > 10s (j limit satisfied)
if 6
•
10
4
≤ L
R_real
≤ 8.89
•
10
6
⇒ t_lim = (5
•
10
5
/L
R_real
)
4
[s] (k limit satisfied)
if 8.89
•
10
6
≤ L
R_real
⇒ t_lim < 10μs (l limit)
if 11mrad < Alpha < 100mrad it is assumed that C
α
= Alpha
if L
R_real
≤ 6
•
10
6
/Alpha ⇒ t > 10s (j limit satisfied)
if 6
•
10
6
/Alpha ≤ L
R_real
≤ 8.89
•
10
8
/Alpha ⇒ t_lim = (5
•
10
7
/(L
R_real
•
Alpha))
4
[s]
(k limit satisfied)
if 8.89
•
10
8
/Alpha ≤ L
R_real
⇒ t_lim < 10μs (l limit)
• Diameter d [m] – Distance R [m]:
o Alpha [rad] angle subtended by the source.
o Omega [sr] solid angle subtended by the source.
o L
R
(100mrad) [W/(m² sr)] radiance calculated assuming that the source angular
dimension is 100mrad.