[ Jennie, Siva, Mayank]
Laser: Axcel ,Model Designation: BF-A64-0130-PP
We removed the Lens(f= 250 mm) in front of M2 meter and we placed a lens (1 m focal length) roughly 1 m away from the m2 meter.
The lens was adjusted so that the beam spot falls roughly at the center of traveling range of the stage.
We measured the M2 of the beam which gave the following result
M²x = 1.09 and M²y= 1.10.
Beam Waist Diameter X =702 µm
Beam Waist Diameter Y =703 µm
Beam Waist Position X =132 mm
Beam Waist Position Y =121 mm
Rayleigh Length X = 332 mm
Rayleigh Length Y =331 mm
The m2 value was better compared to the measurement done with the 250mm lens. However the Beam spot location of X and Y direction were off by 10 mm.
This astigmatism could be because of mismatch between beam and the optics axis of the lens.
We tried manually adjusting the lens but this was the minimum we could get by hand.
we can try tomorrow by placing the lens on a vertical x y stage to get fine movement.