fft beam

calculate the spatial frequency

Parameters

beam frequency

f \(Hz\)

Grid Size

l \(m\)

Sample point

N \(\)

Output

wavelength `lambda`

`lambda=c/f`

wave number k

`k=omega/c`

Max spactial frequency `f_max`

`f_max=N/l 1/2`

spactial resolution `Delta f`

`Delta f=1/l`

Angular spatial frequency `k_max`

`k_max=2pi*f_max`

angular resolution `Delta k`

`Delta k=2pi/l`

max angle `theta_max`

`sin(theta)=sqrt(2) k_max/k`