Back to me some situation. At internal modulation (EI=1=torn on laserhead at max output) head works fine. But when try to modulate it then head like to work with much smaller output... like 200mW not 3000. Signal have 5Vpp for sure
Now, when I write here then works fine. ;/ LD current about 10,5A, output OK but I think why U3 parameter show only 2,8V (not 5V) at modulation input?. It looks like problem in driver (VD-IIIA). This problem exist from long time. At now they run about 300hrs, with two other the same laser head and they work fine.




Next my question, brand new 4W laserhead. I but 3pcs and in each divergence is else and worse like from diode with good lens ;(
Any one try to change it bu yourself?. It's possible without moving crystal or any risk?
Frank suggest to send it back, but it's not fun (shipping cost, time, and litlle too many bug like for me)