8.14. Blazed gratings

In this example we show that blazed grating generates order 1, only when the angle of the grating is the correct one (maximum phase shift = 2\(\pi\)). On the other hand, for other grating angle, several diffraction orders are generated.

[17]:

from diffractio import np, plt
from diffractio import um, mm, degrees

from diffractio.scalar_masks_X import Scalar_mask_X
from diffractio.scalar_masks_XY import Scalar_mask_XY

from diffractio.scalar_sources_XY import Scalar_source_XY
from diffractio.scalar_fields_X import Scalar_field_X

8.14.1. Grating in x mode

Grating with correct phase

[18]:

wavelength = 1*um
focal = 5*mm

x = np.linspace(-3500,3500,2048*8)

[19]:

t_lens_x = Scalar_mask_X(x, wavelength)
t_lens_x.lens(x0=0, focal=focal, radius=0)

[20]:

t_blazed_x = Scalar_mask_X(x, wavelength)
t_blazed_x.blazed_grating(x0=125, period=10, phase_max=2 * np.pi)

[21]:

u1 = t_lens_x * t_blazed_x
u2 = u1.RS(z=focal)
u2.draw()
plt.xlim(-2000, 2000)

Good result: factor 2.04

../../_images/source_examples_scalar_blazed_grating_7_1.png

Grating with wrong phase

[22]:

t_blazed2_x = Scalar_mask_X(x, wavelength)
t_blazed2_x.blazed_grating(x0=125, period=10, phase_max=1.5 * np.pi)

[23]:

u1_x = t_lens_x * t_blazed2_x
u2_x = u1_x.RS(z=focal)
u2_x.draw()
plt.xlim(-2000, 2000)

Good result: factor 2.04

../../_images/source_examples_scalar_blazed_grating_10_1.png

[24]:

tx=Scalar_field_X(x=x, wavelength=wavelength)
tx.incident_field(u1_x)
xout = np.linspace(-3500,3500,512)
z = np.linspace(focal - 2*mm, focal + 2*mm, 512)
txz=tx.CZT(xout=xout, z=z)
txz.draw(logarithm=5)

../../_images/source_examples_scalar_blazed_grating_11_0.png

8.14.2. Grating in XY mode

Grating with correct phase

[32]:

num_pixels = 1024

length = 500*um
x0 = np.linspace(-length/2, length/2, 2*num_pixels)
y0 = np.linspace(-length/2, length/2, num_pixels)
wavelength = 0.6238*um

focal = 5*mm

[33]:

u0_xy = Scalar_source_XY(x=x0, y=y0, wavelength=wavelength)
u0_xy.plane_wave(A=1)
u0_xy.pupil()

[34]:

t_lens_xy = Scalar_mask_XY(x=x0, y=y0, wavelength=wavelength)
t_lens_xy.lens(r0=(0*um, 0*um), focal=focal)

[35]:

t_blazed_xy = Scalar_mask_XY(x=x0, y=y0, wavelength=wavelength)
t_blazed_xy.blazed_grating(period=20*um, phase_max=2 * np.pi, x0=0*um, angle=0*degrees)

[38]:

u1_xy = u0_xy * t_lens_xy * t_blazed_xy

u2_xy = u1_xy.RS(z=focal, new_field=True, amplification=(3, 1))

u2_xy.draw(logarithm=1e3)

../../_images/source_examples_scalar_blazed_grating_17_0.png

Grating with wrong phase

[40]:

t_blazed2_xy = Scalar_mask_XY(x=x0, y=y0, wavelength=wavelength)
t_blazed2_xy.blazed_grating(period=20*um, phase_max=1.5 * np.pi, x0=0*um, angle=0*degrees)

[41]:

u1_xy = u0_xy * t_lens_xy * t_blazed2_xy
u2_xy = u1_xy.RS(z=focal, new_field=True, amplification=(3, 1))
u2_xy.draw(logarithm=1e3)

../../_images/source_examples_scalar_blazed_grating_20_0.png

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