作者s055072 (哈利)
看板Physics
標題[問題] paper內容看不懂 有關光學
時間Sun May 9 23:56:21 2010
內容是這樣
These data represent the total amount of the transmitted light
with both the propagating and evanescent light modes.
她量測了一張近場光學圖像有
包含propagating and evanescent light modes
As the evanescent modes are characterized by an in-plane
component of the wave vector (k平行) larger than its norm
and as the light intensity is periodic for each value of k平行,
the local distribution of evanescent modes can be extracted
by fast Fourier transformation (FFT) using a high-pass filter
with a cut-off frequency of 2/波長 which corresponds to
evanescent modes in air.
我想問的是為什麼
只要做FFT也就是使用一個high-pass filter去處理整個光場圖像
就可以得到evanescent mode的光??
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◆ From: 140.113.244.111
1F：推 mingweii:因為只要frequency滿足sqrt(fx^2+fy^2)>1/lambda, 則其 05/10 11:14
2F：→ mingweii:angular spectrum的transfer function (exp項)的指數會隨 05/10 11:15
3F：→ mingweii:傳播方向衰減, 可以看goodman的Fourier Optics chapter 3 05/10 11:15
4F：→ mingweii:這樣的衰減效應就是evanescent mode 05/10 11:16