Originally Posted by
planters
I didn't know that CN modules were available with this kind of beam spec. In all my experience this is the best laser beam I have ever seen including the ions. But, when using the direct diode pump I can understand why. You actually have to align the cavity for each power level because unless you are incredibly fortunate the thermal lensing is not just a low order plain-o positive lens, but rather an asymmetrical, high order, un-aligned blob. This is much less with a Gaussian or bell shaped and focused fiber homogenized spot.
The problem as I see it with the 888 is that aside from the real benefit of the lower quantum defect, the problem of the very low absorption coefficient is that in order to take advantage of the spreading out of the heat effected region you have to produce a very tight and well collimated pump beam to avoid wasting the pump in regions of the crystal that never "see" the mode.