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Beam divergence was measured using a method called "Focal Length Divergence Measurement Method"
Where a lens of a known focal length is placed on the beam path and the beam waist is measured at the focal distance using a beam profiler.
We ramped the power up to 10 W
for a focal length = 400 mm,
we measured a FWHM = 2.1 mm,
corresponding to a divergence = 4.45 mrad (edit : wrong software use)
for comparison, we measured the FWHM 8.1 mm @ 1.55 m and extracted the divergence directly 4.46 mrad (edit : this measurement is wrong - wrong use of the software)
Note: better to use a lens of a focal lens higher than 100 mm (to reduce the error in the distance measured)
| Manar Amer wrote: |
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The previous Sbox telescope was dismantled and the mechanical components cleaned.
its lenses are still in the mounts, it looks that two of them are spherical and two are cylindrical
2 are -100 mm and 2 are +150 mm, there is also a box containing fused silica lenses that could be used.
Note: at high power use only fused silica lenses not BK7 type
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