Theꢀrecommendedꢀminimumꢀapertureꢀwidthꢀandꢀheightꢀ
isꢀbasedꢀonꢀtheꢀassumptionꢀthatꢀtheꢀcenterꢀofꢀtheꢀwindowꢀ
andꢀtheꢀcenterꢀofꢀtheꢀmoduleꢀareꢀtheꢀsame.ꢀItꢀisꢀrecom-
mendedꢀ thatꢀ theꢀ toleranceꢀ forꢀ assemblyꢀ beꢀ consideredꢀ
asꢀwell.ꢀTheꢀminimumꢀwindowꢀsizeꢀwhichꢀwillꢀtakeꢀintoꢀ
accountꢀofꢀtheꢀassemblyꢀtoleranceꢀisꢀdefinedꢀas:
Module Depth
Aperture Width (x, mm) Aperture height (y, mm)
(z) mm
Max
min
Max
4.99
Min
2.32
2.85
3.39
3.92
4.46
4.99
5.53
6.07
6.60
7.ꢀ4
0
ꢀ
2
3
4
5
6
7
8
9
ꢀ0.09
ꢀꢀ.24
ꢀ2.40
ꢀ3.55
ꢀ4.7ꢀ
ꢀ5.86
ꢀ7.02
ꢀ8.ꢀ7
ꢀ9.33
20.48
7.42
7.95
6.ꢀ4
Xꢀ (minꢀ +ꢀ assemblyꢀ tolerance)ꢀ =ꢀ Xminꢀ +ꢀ 2*(assemblyꢀ
tolerance)ꢀ(Dimensionsꢀareꢀinꢀmm)
8.49
7.30
9.02
8.45
Yꢀ (minꢀ +ꢀ assemblyꢀ tolerance)ꢀ =ꢀ Yminꢀ +ꢀ 2*(assemblyꢀ
tolerance)ꢀ(Dimensionsꢀareꢀinꢀmm)
9.56
9.6ꢀ
ꢀ0.09
ꢀ0.63
ꢀꢀ.ꢀ7
ꢀꢀ.70
ꢀ2.24
ꢀ0.76
ꢀꢀ.92
ꢀ3.07
ꢀ4.23
ꢀ5.38
Window Material
Almostꢀ anyꢀ plasticꢀ materialꢀ willꢀ workꢀ asꢀ aꢀ windowꢀ
material.ꢀ Polycarbonateꢀ isꢀ recommended.ꢀ Theꢀ surfaceꢀ
finishꢀ ofꢀ theꢀ plasticꢀ shouldꢀ beꢀ smooth,ꢀ withoutꢀ anyꢀ
texture.ꢀ Anꢀ IRꢀ filterꢀ dyeꢀ mayꢀ beꢀ usedꢀ inꢀ theꢀ windowꢀ toꢀ
makeꢀitꢀlookꢀblackꢀtoꢀtheꢀeye,ꢀbutꢀtheꢀtotalꢀopticalꢀlossꢀ
ofꢀ theꢀ windowꢀ shouldꢀ beꢀ 10%ꢀ orꢀ lessꢀ forꢀ bestꢀ opticalꢀ
performance.ꢀLightꢀlossꢀshouldꢀbeꢀmeasuredꢀatꢀ885ꢀnm.ꢀ
Theꢀrecommendedꢀplasticꢀmaterialsꢀforꢀuseꢀasꢀaꢀcosmeticꢀ
windowꢀareꢀavailableꢀfromꢀGeneralꢀElectricꢀPlastics.ꢀ
25
20
15
10
5
Xmax
Xmin
Recommended Plastic Materials:
Material #
Lexan ꢀ4ꢀ
Lexan 920A
Lexan 940A
Haze
ꢀꢁ
Refractive Index
ꢀ.586
88ꢁ
85ꢁ
85ꢁ
ꢀꢁ
ꢀ.586
ꢀꢁ
ꢀ.586
Note:ꢀ920Aꢀandꢀ940Aꢀareꢀmoreꢀflameꢀretardantꢀthanꢀ141.
0
0
1
2
3
4
5
6
7
8
9
RecommendedꢀDye:ꢀVioletꢀ#21051ꢀ(IRꢀtransmissantꢀaboveꢀ
625mm)
Module Depth (z) mm
Figure D2. Aperture Height (x) vs. Module Depth (z)
Shape of the Window
Fromꢀ anꢀ opticsꢀ standpoint,ꢀ theꢀ windowꢀ shouldꢀ beꢀ flat.ꢀ
Thisꢀ ensuresꢀ thatꢀ theꢀ windowꢀ willꢀ notꢀ alterꢀ eitherꢀ theꢀ
radiationꢀpatternꢀofꢀtheꢀLED,ꢀorꢀtheꢀreceiveꢀpatternꢀofꢀtheꢀ
photodiode.ꢀIfꢀtheꢀwindowꢀmustꢀbeꢀcurvedꢀforꢀmechani-
calꢀorꢀindustrialꢀdesignꢀreasons,ꢀplaceꢀtheꢀsameꢀcurveꢀonꢀ
theꢀbacksideꢀofꢀtheꢀwindowꢀthatꢀhasꢀanꢀidenticalꢀradiusꢀasꢀ
theꢀfrontꢀside.ꢀWhileꢀthisꢀwillꢀnotꢀcompletelyꢀeliminateꢀtheꢀ
lensꢀeffectꢀofꢀtheꢀfrontꢀcurvedꢀsurface,ꢀitꢀwillꢀsignificantlyꢀ
reduceꢀtheꢀeffects.ꢀTheꢀamountꢀofꢀchangeꢀinꢀtheꢀradiationꢀ
patternꢀ isꢀ dependentꢀ uponꢀ theꢀ materialꢀ chosenꢀ forꢀ theꢀ
window,ꢀtheꢀradiusꢀofꢀtheꢀfrontꢀandꢀbackꢀcurves,ꢀandꢀtheꢀ
distanceꢀfromꢀtheꢀbackꢀsurfaceꢀtoꢀtheꢀtransceiver.ꢀOnceꢀ
theseꢀitemsꢀareꢀknown,ꢀaꢀlensꢀdesignꢀcanꢀbeꢀmadeꢀwhichꢀ
willꢀ eliminateꢀ theꢀ effectꢀ ofꢀ theꢀ frontꢀ surfaceꢀ curve.ꢀTheꢀ
followingꢀdrawingsꢀshowꢀtheꢀeffectsꢀofꢀaꢀcurvedꢀwindowꢀ
onꢀtheꢀradiationꢀpattern.ꢀInꢀallꢀcases,ꢀtheꢀcenterꢀthicknessꢀ
ofꢀtheꢀwindowꢀisꢀ1.5ꢀmm,ꢀtheꢀwindowꢀisꢀmadeꢀofꢀpolycar-
bonateꢀplastic,ꢀandꢀtheꢀdistanceꢀfromꢀtheꢀtransceiverꢀtoꢀ
theꢀbackꢀsurfaceꢀofꢀtheꢀwindowꢀisꢀ3ꢀmm.
18
Ymax
Ymin
16
14
12
10
8
6
4
2
0
0
1
2
3
4
5
6
7
8
9
Module Depth (z) mm
Figure D3. Aperture Height (y) vs. Module Depth (z)
ꢀ6