6.4.1. Drawing in logarithm scale
When showing intensity distribution, sometimes we need to analyze tiny intensity distributions that are hidden by a high intensity peak. Most of methods for visualization of intensity, present the logarithm parameter, which can be False, True, or a number. the function used to increase the color scale is:
u = np.log(logarithm * u + 1).
We show two examples where this parameter is important: The intensity distribution at the focal distance from a len, and the far field diffraction pattern of a small square aperture.
[1]:
from diffractio import degrees, mm, um, nm
from diffractio import np, plt, sp
from diffractio.scalar_masks_XY import Scalar_mask_XY
from diffractio.scalar_sources_XY import Scalar_source_XY
6.4.1.1. Intensity at the focal distance from a lens
[2]:
radius = 3 * mm
x0 = np.linspace(-radius, radius, 512)
y0 = np.linspace(-radius, radius, 512)
xout = np.linspace(-100 * um, 100 * um, 128)
yout = np.linspace(-100 * um, 100 * um, 128)
wavelength = 550 * nm
focal = 250 * mm
z = focal
[3]:
t0 = Scalar_mask_XY(x0, y0, wavelength)
t0.lens(r0=(0, 0), focal=focal, radius=radius)
u0 = Scalar_source_XY(x0, y0, wavelength)
u0.plane_wave(A=1)
u1 = t0 * u0
[4]:
u1.draw('phase')
[5]:
u2 = u1.CZT(z, xout, yout)
[6]:
u2.draw(has_colorbar='vertical')
[7]:
u2.draw(logarithm=1)
6.4.1.2. Far field diffraction pattern of a small square aperture
[8]:
radius = 3 * mm
x0 = np.linspace(-radius, radius, 1024)
y0 = np.linspace(-radius, radius, 1024)
xout = np.linspace(-100 * um, 100 * um, 128)
yout = np.linspace(-100 * um, 100 * um, 128)
[9]:
focal = 2 * mm
z = focal
t0 = Scalar_mask_XY(x0, y0, wavelength)
t0.lens(r0=(0, 0), focal=focal, radius=radius)
t1 = Scalar_mask_XY(x0, y0, wavelength)
t1.square(r0=(0, 0), size=100 * um, angle=0)
u0 = Scalar_source_XY(x0, y0, wavelength)
u0.plane_wave()
u1 = t0 * t1 * u0
[10]:
u2 = u1.CZT(z, xout, yout)
[12]:
u2.draw(has_colorbar='vertical')
[13]:
u2.draw(logarithm=1)
[14]:
u2.draw(logarithm=1e2)
