光學作業 應物三甲 0932350 葉昭呈
8-21
Consider a light source consisting of two components with different wavelength
1 and  2 . Let light form this source be incident on a scanning Fabry-Perot
interferometer of nominal length d  5cm . Let the scaled transmittance through the
Fabry-Perot as a function of the change in cavity length be as shown in Figure 8-20a
and 8-20b. Figure 8-20b shows the first set of dual peaks of Figure 8-20a over a
smaller length scale in order to allow a closer examination of the structure of the
overlapping peaks.
(a) What is the nominal wavelength of the light source?
(b) Estimate the difference  2 - 1 in wavelength of the two components presuming
that the overlapping transmittance peaks have the same mode
number , m2  m1  m
(c) Estimate the difference  2 - 1 in wavelength of the two components presuming
that the overlapping transmittance peaks have mode number that differ by 1,so
that m2  m1  1
Ans:
(a) the nominal wavelength very near 1 and  2
1
 0.298-0.048=0.25 m ,
2
the nominal wavelength= 1 =0.5 m
由圖知
(b)
d1  m
1
2
d 2  d1 
 =
, d2  m
2
2
m
m
( 2  1 )  d  
2
2
2(0.002)
2d 2d


=2  10 8 m
2
2
d
m
2  5  10

0.5  10  6
(c)
d1  m
1
2
d 2  d1 
 =
, d 2  (m  1)
2
2


m
m
( 2  1 ) + 2  d   + 2
2
2
2
2
2
0.5
)
2 
2 = -2.48  10 6 m
m
2  5  10  2
0.5  10  6
2(d 
)
2(0.002 