Óptica Moderna Fundamentos e aplicações - Fotonica.ifsc.usp.br ...
Óptica Moderna Fundamentos e aplicações - Fotonica.ifsc.usp.br ...
Óptica Moderna Fundamentos e aplicações - Fotonica.ifsc.usp.br ...
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182<<strong>br</strong> />
Logo,<<strong>br</strong> />
0<<strong>br</strong> />
-0.5<<strong>br</strong> />
ω2<<strong>br</strong> />
ω2 ω2 ω1<<strong>br</strong> />
∫ = + = −<<strong>br</strong> />
ω ∫ ∫ 1 ω1<<strong>br</strong> />
0 ∫0 ∫0<<strong>br</strong> />
0.5<<strong>br</strong> />
S(ω)<<strong>br</strong> />
0.5<<strong>br</strong> />
0.5<<strong>br</strong> />
C(ω)<<strong>br</strong> />
Difração<<strong>br</strong> />
S. C. Zilio <strong>Óptica</strong> <strong>Moderna</strong> – <strong>Fundamentos</strong> e Aplicações<<strong>br</strong> />
-0.5<<strong>br</strong> />
ω<<strong>br</strong> />
Fig. 8.21 - Espiral de Cornu.<<strong>br</strong> />
= C<<strong>br</strong> />
No caso da eq. (8.42) que estamos estudando,<<strong>br</strong> />
( ω2<<strong>br</strong> />
) − C(<<strong>br</strong> />
ω1<<strong>br</strong> />
) + iS(<<strong>br</strong> />
ω2<<strong>br</strong> />
) − iS(<<strong>br</strong> />
ω1<<strong>br</strong> />
CπL<<strong>br</strong> />
U( P)<<strong>br</strong> />
= { [ C(<<strong>br</strong> />
u 2 ) − C(<<strong>br</strong> />
u1<<strong>br</strong> />
) ] + i[<<strong>br</strong> />
S(<<strong>br</strong> />
u 2 ) −S(<<strong>br</strong> />
u1<<strong>br</strong> />
) ] }<<strong>br</strong> />
k<<strong>br</strong> />
x{ [ C(<<strong>br</strong> />
v ) C(<<strong>br</strong> />
v ) ] + i[<<strong>br</strong> />
S(<<strong>br</strong> />
v ) − S(<<strong>br</strong> />
v ) ] }<<strong>br</strong> />
2<<strong>br</strong> />
1<<strong>br</strong> />
2<<strong>br</strong> />
1<<strong>br</strong> />
) (8.44)<<strong>br</strong> />
− (8.45)<<strong>br</strong> />
Para uma abertura infinita, isto é, sem nenhum obstáculo para<<strong>br</strong> />
2<<strong>br</strong> />
difração, u1<<strong>br</strong> />
= v 1 = -∞ e u2<<strong>br</strong> />
= v 2 = ∞ e, portanto, U 0 = (CπL/k)(1 + i) .<<strong>br</strong> />
Assim, a expressão para a difração por uma abertura retangular pode ser<<strong>br</strong> />
re-escrita como:<<strong>br</strong> />
U 0<<strong>br</strong> />
U( P)<<strong>br</strong> />
= { [ C(<<strong>br</strong> />
u 2 ) − C(<<strong>br</strong> />
u1<<strong>br</strong> />
) ] + i[<<strong>br</strong> />
S(<<strong>br</strong> />
u 2 ) − S(<<strong>br</strong> />
u1<<strong>br</strong> />
) ] }<<strong>br</strong> />
2<<strong>br</strong> />
1+<<strong>br</strong> />
i<<strong>br</strong> />
( )<<strong>br</strong> />
{ [ C(<<strong>br</strong> />
v ) C(<<strong>br</strong> />
v ) ] + i[<<strong>br</strong> />
S(<<strong>br</strong> />
v ) S(<<strong>br</strong> />
v ) ] }<<strong>br</strong> />
x − −<<strong>br</strong> />
(8.46)<<strong>br</strong> />
2<<strong>br</strong> />
1<<strong>br</strong> />
2<<strong>br</strong> />
1