gbeampro
gbeampro is a small Python package for designing gaussian laser beam propagation and transformations (e.g., focusing and collimation, refraction at crystal interface, etc.).
Example: Beam focusing into a slab of crystal
To compute the waist diameter inside the crystal and find the confocal parameter (collimated range).
import ndispers as nd
import numpy as np
import matplotlib.pyplot as plt
from gbeampro.beambase import GaussBeam# setup a GaussBeam instance
b1 = GaussBeam(wl_um=1.064, n=1.0, z_mm=0, R_mm=np.infty, w_mm=1.5)b1GaussBeam(wl_um=1.06400, n=1.000000, z_mm=0.00000, R_mm=inf, w_mm=1.50000)
q : 0.00000e+00 -6.64341e+03i
theta : 2.257878e-01 mrad
# converge by a thin lens (f=150 mm)
b1.thinlens(150)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=0.00000, R_mm=-1.50000e+02, w_mm=1.50000)
q : -1.49924e+02 -3.38509e+00i
theta : 2.257878e-01 mrad
# propagate upto crystal interface
# + 5 distance tries to bring the wasit location at the center of the crystal
b1.propagate(150 - 20*0.5 + 5)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=145.00000, R_mm=-7.25091e+00, w_mm=0.05977)
q : -4.92357e+00 -3.38509e+00i
theta : 5.666828e+00 mrad
# Air-Crystal interface
Xtal = nd.media.crystals.LBO_Newlight_xy() # crystal object
n2 = Xtal.n(1.064, 0, 149, pol='o') # refractive index of the crystal
b1.interface(n2)GaussBeam(wl_um=1.06400, n=1.604333, z_mm=145.00000, R_mm=-1.16329e+01, w_mm=0.05977)
q : -7.89905e+00 -5.43082e+00i
theta : 3.532224e+00 mrad
# propagate inside crystal (length 20 mm)
b1.propagate(20)GaussBeam(wl_um=1.06400, n=1.604333, z_mm=165.00000, R_mm=1.45383e+01, w_mm=0.08270)
q : 1.21010e+01 -5.43082e+00i
theta : 2.552784e+00 mrad
# Crystal-Air interface
b1.interface(1.0)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=165.00000, R_mm=9.06187e+00, w_mm=0.08270)
q : 7.54267e+00 -3.38509e+00i
theta : 4.095503e+00 mrad
# propagate in air upto a lens
# + 5 distance tries to collimate after lens 2
b1.propagate(200 - 20*0.5 + 5)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=360.00000, R_mm=2.02599e+02, w_mm=2.02623)
q : 2.02543e+02 -3.38509e+00i
theta : 1.671490e-01 mrad
# collimate by a thin lens (f=200mm)
b1.thinlens(200)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=360.00000, R_mm=-1.55891e+04, w_mm=2.02623)
q : -5.87433e+03 -7.55432e+03i
theta : 1.671490e-01 mrad
# propagate in air by distance 100 mm
b1.propagate(100)GaussBeam(wl_um=1.06400, n=1.000000, z_mm=460.00000, R_mm=-1.56573e+04, w_mm=2.01330)
q : -5.77433e+03 -7.55432e+03i
theta : 1.682224e-01 mrad
# plot beam trajectory
fig, (ax1, ax2, ax3, ax4) = plt.subplots(4, 1, sharex=True, figsize=(8, 16), facecolor="white")
b1.plot_n(ax1)
b1.plot_w(ax2)
b1.plot_R(ax3)
b1.plot_theta(ax4)
# search beam waists
b1.search_BeamWaists()Beam waists in z range [0.000, 460.000000] mm
--------------------------------------------------
No.0:
Waist location, z : 0.0000 mm
Refractive index, n : 1.0000
Waist spot diamter, 2*w0 : 3000.0 µm
Confocal parameter (2*Rayleigh range) : 13286.81 mm
2.84 * Confocal parameter : 37734.54 mm
No.1:
Waist location, z : 152.9000 mm
Refractive index, n : 1.6043
Waist spot diamter, 2*w0 : 67.7 µm
Confocal parameter (2*Rayleigh range) : 10.86 mm
2.84 * Confocal parameter : 30.85 mm
No.2:
Waist location, z : 360.0000 mm
Refractive index, n : 1.0000
Waist spot diamter, 2*w0 : 4052.5 µm
Confocal parameter (2*Rayleigh range) : 24244.54 mm
2.84 * Confocal parameter : 68854.49 mm
You can see the focusing condition at the above result No.1.
