Simple and fast calculation of beam sizes from a single monochrome image based on the ISO 11146 method of variances. Some effort has been made to make the algorithm less sensitive to background offset and noise.
Just use pip:
pip install laserbeamsize
Finding the center and dimensions of a good beam image:
import imageio
import numpy as np
import laserbeamsize as lbs
beam = imageio.imread("t-hene.pgm")
x, y, dx, dy, phi = lbs.beam_size(beam)
print("The center of the beam ellipse is at (%.0f, %.0f)" % (x,y))
print("The ellipse diameter (closest to horizontal) is %.0f pixels" % dx)
print("The ellipse diameter (closest to vertical) is %.0f pixels" % dy)
print("The ellipse is rotated %.0f° ccw from the horizontal" % (phi*180/3.1416))
ellipticity = dy/dx
if ellipticity>0.87:
print()
print("The beam is circular because the ellipticity=%.2f > 0.87")
print("The circular beam diameter is %.0f pixels" % np.sqrt((dx**2+dy**2)/2))
Alternatively, one can get a quick visual report:
lbs.visual_report(beam) plt.show()
Which will show something like
Alternatively:
tem02 = imageio.imread("TEM02_100mm.pgm") >> 4
lbs.visual_report(tem02, title = r"TEM$_{02}$ at z=100mm", pixel_size=3.75)
plt.savefig("tem02.png", bbox_inches = 'tight')
Creates an image like
Documentation about backgrounds, integrations, and other issues are explained at <https://laserbeamsize.readthedocs.io>
laserbeamsize is licensed under the terms of the MIT license.