Raw LD output...pouring into the first cylindrical.....Holy Sh$t.....Well.....therein lies the problem of not fitting that Near Field geometry onto this very small Cylindrical lenses.
The beam slow axis is rapidly diverging....every mm down beam of the LD window !!!
I do not know what you have room for....but I would sure throw a 2mm EFL Collimation lens in front of that LD !!!!!!
I appreciate the drive to keep things small....but....elimination of the Collimation lens...is....well....unadvisable !!
Good Luck !!
Though I've searched the interweb I've not found an answer.I hear ya.
The loss from that first optic is not huge. As I said, the divergence figures straight out of the diode, in reality, seem to be a bit worse than what is specified on the datasheet.
Theoretically, the small diameter lenses should have been sufficient but I didn't expect it to be perfect. I am pretty content with the beam profile despite the 25% loss to the optics (excusing the wings).
Seeing what I have here I wonder if the aspheric collimator will help a bit with the lobes/wings/whatever.
Do you report a number for losses in your Dragon's Head build?
I'll go check that thread again...
Edit: it appears you're getting just under 1W at around 1200mA.
Based on what to expect with a regular ol' lens in front of the diode, that doesn't seem too bad.
When beam correcting to a circular profile do you first collimate then circularize?
Or do you circularize the beam then collimate.
Can the beam be circularize to round sufficiently to not need additional collimation for lowering the beam divergence?