Table 5.4
PROFILE GEOMETRY OF PARABOLAS (f = 0.9 mm, 0.7 mm, 0.66mm)
f
r
x
z
F
(deg.)
F
(rad.)
(mm)
(mm)
(mm)
(mm)
0.9
20
22
25
30
35
40
45
50
55
60
65
70
20
22
25
30
35
40
45
50
55
60
65
70
20
22
25
30
35
40
45
50
55
60
65
70
0.35
0.38
0.44
0.52
0.61
0.70
0.79
0.87
0.96
1.05
1.13
1.22
0.35
0.38
0.44
0.52
0.61
0.70
0.79
0.87
0.96
1.05
1.13
1.22
0.35
0.38
0.44
0.52
0.61
0.70
0.79
0.87
0.96
1.05
1.13
1.22
29.85
24.72
19.21
13.44
9.95
7.69
6.15
5.04
4.22
3.60
3.12
2.74
23.21
19.23
14.94
10.45
7.74
5.98
4.78
3.92
3.28
2.80
2.42
2.13
21.89
18.13
14.09
9.85
7.30
5.64
4.51
3.70
3.10
2.64
2.29
2.01
10.21
9.26
8.12
6.72
5.71
4.95
4.35
3.86
3.46
3.12
2.83
2.57
7.94
7.20
6.31
5.22
4.44
3.85
3.38
3.00
2.69
2.42
2.20
2.00
7.49
6.79
5.95
4.93
4.19
3.63
3.19
2.83
2.54
2.29
2.07
1.89
28.05
22.92
17.41
11.64
8.15
5.89
4.35
3.24
2.42
1.80
1.32
0.94
21.81
17.83
13.54
9.05
6.34
4.58
3.38
2.52
1.88
1.40
1.02
0.73
20.57
16.81
12.77
8.53
5.98
4.32
3.19
2.38
1.78
1.32
0.97
0.69
0.70
0.66
Collimating Lens Design
In this section we will deal with spherical lenses
and geometrical optics design techniques,
treating the LED as a point source of light. More
sophisticated and accurate methods exist, but
are beyond the scope of this application note.
Where:
f = focal length of the lens
n = index of refraction of the lens material
R1= radius of lens surface nearest the LED
R2= radius of other lens surface
T = thickness of the lens
An LED signal lamp with a dual-convex,
collimator lens is shown in Figure 5.28. The
“lensmaker’s” formula for this arrangement
is shown below:
If T is less than one sixth of the diameter of the
lens, then this equation simplifies to:
17
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