光學系統的截止頻率計算

數值孔徑 (Numerical Aperture, NA) 計算

Na = \frac {D} {2f} 

解析度 (Resolution) 計算

Resolution = \frac {\lambda}{2NA} 

截止頻率計算

f_0= \frac {D}{2 \lambda f} 

f_0= \frac{1}{\lambda} \frac{D}{2f}

f_0= \frac{NA}{\lambda} 
```

解析度與截止頻率關係
----------

```
Resolution = \frac{1}{2f_0} = \frac{\lambda}{2NA} 
```