7.11. 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.

[3]:

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_XZ import Scalar_field_XZ

7.11.1. Grating in x mode

Grating with correct phase

[4]:

wavelength = 1 * um
focal = 5 * mm

x = np.linspace(-3500,3500,2048*8)
z = np.linspace(focal - 2 * mm, focal + 2 * mm, 128)

[5]:

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

[6]:

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

[7]:

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_blazed_grating_7_1.png

Grating with wrong phase

[8]:

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

[19]:

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_blazed_grating_10_1.png

[10]:

txz=Scalar_field_XZ(x=x, z=z, wavelength=wavelength)
txz.incident_field(u1_x)
txz.RS()
txz.draw(logarithm=5)

../../_images/source_examples_blazed_grating_11_0.png

7.11.2. Grating in XY mode

Grating with correct phase

[11]:

num_pixels = 512

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

focal = 5 * mm

[12]:

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

[13]:

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

[14]:

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)

[15]:

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=1e1)

../../_images/source_examples_blazed_grating_17_0.png

Grating with wrong phase

[16]:

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)

[17]:

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=1e1)

../../_images/source_examples_blazed_grating_20_0.png