HSDL-3220-001 HP [Agilent(Hewlett-Packard)], HSDL-3220-001 Datasheet - Page 16

• Manufacturer Part Number: HSDL-3220-001
• Manufacturer: HP [Agilent(Hewlett-Packard)]

16
Appendix D: Window Designs for HSDL-3220
Optical port dimensions for
HSDL-3220
To ensure IrDA compliance, some
constraints on the height and
width of the window exist. The
minimum dimensions ensure
that the IrDA cone angles are met
without vignetting. The maxi-
mum dimensions minimize the
effects of stray light. The mini-
mum size corresponds to a cone
angle of 30° and the maximum
size corresponds to a cone angle
of 60° .
In the figure below, X is the
width of the window, Y is the
Figure 19. Window design diagram.
IR TRANSPARENT
MATERIAL
OPAQUE
WINDOW
Y
Z
D
IR TRANSPARENT WINDOW
A
X
K
height of the window and Z is the
distance from the HSDL-3220 to
the back of the window. The
distance from the center of the
LED lens to the center of the
photodiode lens, K, is 5.1mm.
The equations for computing the
window dimensions are as
follows:
X = K + 2 * (Z+D) * tanA
Y = 2 * (Z+D) * tanA
The above equations assume that
the thickness of the window is
negligible compared to the
distance of the module from the
back of the window (Z). If they are
OPAQUE
MATERIAL
comparable, Z' replaces Z in the
above equation. Z' is defined as
Z' = Z + t/n
where ‘t’ is the thickness of the
window and ‘n’ is the refractive
index of the window material.
The depth of the LED image
inside the HSDL-3220, D, is
3.17 mm. ‘A’ is the required half
angle for viewing. For IrDA
compliance, the minimum is 15°
and the maximum is 30° . Assum-
ing the thickness of the window
to be negligible, the equations
result in the following tables and
graphs.