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< >Broadband AR for a Cone of Light</P>! {4 c; y6 m) l% i/ b' h
<>Here we consider a coating on glass that reflects only 0.5% of a cone of light for a range of wavelengths from 420 to 680 nm. The cone axis is normal to the glass. The cone has an F-number of 0.778, which means the half-angle is 40 degrees. An uncoated glass surface reflects 4.4% of this cone of light. We use a feature new to version 3.5: cone-angle targets. As optimization targets we use 7 e3 j! g/ a, B0 f! N2 B
<><BR>R < 0.5% for wavelengths 420, 425, 430,..., 680 and for a 40-degree cone
+ z0 G1 g6 z8 x0 l9 J<><BR>In TFCalc, these targets are easy to enter by using the "Generate Cone Targets" command on the Options menu of the "Targets - Cone Angle" window. We use TFCalc's needle/tunneling optimization to design the coating from "scratch". That is, we begin the design process with a single thin layer of TiO2 and allow TFCalc to increase the thickness and number of layers in the design. TFCalc finds a 6-layer design in a few minutes. The performance of this design is shown below. The little circles indicate the optimization targets.
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< align=center> </P>
& L5 T7 s# n+ B9 M* J<>Here is the design, starting with the layer closest to glass, and with thicknesses given in nm: </P>. T# x( }, u8 L/ A$ g8 @5 ?
<><RE>TIO2 11.04
4 F. d5 Q/ `: m8 j; [SIO2 44.43
& s2 `3 W( y( y0 t8 L* U% A% Y1 sTIO2 34.99! S/ u( C# v* m
SIO2 28.25
5 D) ^" T4 q- ^, N! a' zTIO2 30.464 q, V* e: O; }8 Q' k
SIO2 104.92
8 N' o* y V! K/ h5 G$ L</PRE> |
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发表于 2005-8-23 06:28:01
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