11

FN7464.2

December 12, 2006

Window with Light Guide Design

If a smaller window is desired while maintaining a wide

effective viewing angle of the ISL29003, a cylindrical piece of

transparent plastic is needed to trap the light and then focus

and guide the light on to the device. Hence the name light

guide or also known as light pipe. The pipe should be placed

directly on top of the device with a distance of D1 = 0.5mm

to achieve peak performance. The light pipe should have

minimum of 1.5mm in diameter to ensure that whole area of

the sensor will be exposed. See Figure 5.

TABLE 16. RECOMMENDED DIMENSIONS FOR A FLAT

WINDOW DESIGN

D1

VIEWING ANGLE

VIEWING ANGLE

1.5

0.50

2.25

3.75

2.0

1.00

3.00

4.75

2.5

1.50

3.75

5.75

3.0

2.00

4.30

6.75

3.5

2.50

5.00

7.75

t = 1

Thickness of lens

D1

Distance between ISL29001 and inner edge of lens

Diameter of lens

Distance constraint between the ISL29001 and lens

outer edge

* All dimensions are in mm.

t

L

LIGHT PIPE

ISL29003

FIGURE 5. WINDOW WITH LIGHT GUIDE/PIPE

ISL29003