※ 引述《melvyn (Aeneas)》之銘言：
: [領域] 光學
: [來源]   課本習題(Pedrotti, Introduction to optics 3rd Ed.
:                   Pearson Education, 2007)
: [題目]Q1. The separatopm pf a certain doublet 0.0055 nm at a wavelength of
:           490 nm. A variable-spaced Fabry-Perot interferometer is used to
:           examine the doublet. At what spacing does the (m)th order of one
:           component coincide with the (m+1)th order of the other.
:       The ans of Q1 is 2.18 cm
:       Q2. White light is passed through a Fabry-Perot interferometer in the
:           arrangement shown in Figure,where the detector is a spectroscope.
:           A series of bright bands appear.When mercury light is simultaneously
:           admitted intto the spectroscope slit,150 of the bright bands are
:           seen to fall between the violet and green lines of mercury at
:           435.8 nm and 546.1 nm,respectively.What is the thickness of the
:           etalon?
:           Figure:http://0rz.tw/b04d4
:        The ans of Q2 is 0.161 mm
: [瓶頸]
: 這兩題我都利用 d = mλ/2 ,可是都與課本給的答案不符
: 想請問錯再哪？

L = mλ/2

=> λ = 2L/m

=> dλ/dm = -2L/(m^2)

=> Δλ≒ (2L/(m^2))*Δm   or   將 m = 2L/λ代入可得

=> Δλ= ((λ^2)/2L)*Δm

=> 2L = ((λ^2)/Δλ)*Δm

For Q1:

        Δλ= 0.0055nm ， λ= 490nm  且 Δm = 1

      => Ans: 2.18 cm

For Q2:

        Δλ= 546.1nm-435.8nm = 110.3nm ， Δm = 150

        且 λ≒ (546.1nm+435.8nm)/2 = 490.95nm

      => Ans: 0.164 mm (誤差有點大)

我想大概是這樣吧

有錯請指教

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※ 編輯: jack6353        來自: 140.113.94.97        (05/29 23:33)