For product information and a complete list of distributors, please go to our web site: www.avagotech.com
Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries.
Data subject to change. Copyright © 2005-2009 Avago Technologies. All rights reserved. Obsoletes AV02-0779EN
AV02-2259EN - November 26, 2009
Appendix C: Recommended window and light guide for HSDL-9100
Option 1
Option 2
Option 3
Option 4
Close to the window
Flat Window (Transmission rate >85%)
Flat Window (Transmission rate >85%)
Flat Window (Transmission rate >85%)
Flat Window (Transmission rate >85%)
Photodiode
LED
LED
Photodiode
LED
Photodiode
LED
Photodiode
Some constraints on the design and position of the win-
dow are required so that the cross talk from the emitter
to the photodiode is minimized. Four recommendations
of window design are suggested as below:
x Put the optical sensor close to the window material.
(See option 1)
x Using baffle in between emitter and detector will
reduce the crosstalk caused by bottom surface. It is rec-
ommended to extend the baffle into the flat window as
to reduce the crosstalk caused by top surface too. (See
option 2)
x Using opaque material of light pipes with two holes as
light path. The structure need to be carefully designed
to minimize the signal loss and crosstalk. (See option 3)
x Using separate pieces of light guide bonded together
for emitter and photo sensor respectively. Insert a baffle
in between the two light guides. (See option 4)
Recommended Window Material
Almost any plastic material will work as a window mate-
rial. Polycarbonate is recommended. The surface finish
of the plastic should be smooth, without any texture.
The thickness of the window material is recommended
to be less than 0.5mm. An IR filter dye may be used in
the window to make it look black to the eye but the total
optical loss of the window should be 10% or less for best
optical performance. Light loss should be measured at
875nm. The recommended plastic materials for use as a
cosmetic window are available for General Electric Plas-
tics.
Recommended Plastic Materials:
Material #
Light
Transmission Haze
Refractive
Index
Lexan 141 88% 1% 1.586
Lexan 920A 85% 1% 1.586
Lexan 940A 85% 1% 1.586
Note:
920A and 940A are more flame retardant than 141.
Recommended Dye: Violet #21051 (IR transmissant above 625 nm)
