Coupling power from this 866nm #laser into a single-mode fibre took some aligning, but I got 1/3 of it in: 23mW of about 70mW total.   It helped when I installed the lenses and fibres for the correct wavelength range (it also helped when I hadn't bolted the coupler to the wrong set of holes and lost most of the beam).     #physics<p><a href='posts/202610/post-20261008-203552-a.jpg'><img src='posts/202610/post-20261008-203552-a.jpg' loading='lazy' /></a></p><p><a href='posts/202610/post-20261008-203552-b.jpg'><img src='posts/202610/post-20261008-203552-b.jpg' loading='lazy' /></a></p>