Laserwave PBS loss questions

[swamidog]

I'm assembling a dual beam combiner and I'm noticing quite a bit of loss from my PBS cube.

I glued the cube to the mount, then I'm turning it by rotating the diodes and keeping an eye on the power level fluctuations on my laser meter. I think I've got things aligned pretty well, but I'm seeing a loss of about 30mW per diode through the PBS cube.

These are red diodes (lpc-815's) and a red PBS cube from Laserwave. I happened to also have a 405nm Laserwave PBS cube sitting around and I dropped that in the beam path and metered only 10mW loss. (21% loss on the red PBS, and 7% loss on the blue).

Any suggestions? What sort of loss should I expect, and why would I see less loss on the blue?

Here's a few thousand words. The red PBS is mounted in the red flexure mount. The blue PBS is unmounted. The 172mW meter reading is without either PBS cube.

dual-on-4.jpgpbs-red.jpgpbs-blue.jpg

[Doc]

This is a known issue with the current Lasrwave red PBS, they have a new unit in testing and due for release.

I am losing 400mW of red through my cube

[Laserman532]

When you were measuring the blue cube were you measuring the thru beam or the reflected beam...that is important.

hoping bridge gets to see this when he is back from holiday...we need very good notch PBS cubes. If anyone can do it for us bridge can!

[swamidog]

I just measured the through beam on the blue PBS. I wrote to
Bridge and am waiting for his reply.

When you were measuring the blue cube were you measuring the thru beam or the reflected beam...that is important.

hoping bridge gets to see this when he is back from holiday...we need very good notch PBS cubes. If anyone can do it for us bridge can!

[Laserman532]

it dosnt make sense that you lost 21% on the thru for the red pbs...that seems real high. Are you confident diode rotation is optimized?

The reflected % is the more important measurement, it determines coating efficiency.

[Doc]

it dosnt make sense that you lost 21% on the thru for the red pbs...that seems real high. Are you confident diode rotation is optimized?

The reflected % is the more important measurement, it determines coating efficiency.

Very much like the problem with the original LW red dichro; there is an angle problem.

You can set it so there is very little loss, but only with the reflected beam exiting 15 degrees or so away from the through beam. Turn the cube to realign the the farfield and you lose the power from the through beam. Doh.

[daedal]

I believe LaserWave has repaired this issue now. I have some new PBS cubes from Bridge and they measure reflection at ~99% and transmission at ~95%!!

Shameless plug: These will be available on the store below tonight

--DDL

[swamidog]

any trade up policy?

I believe LaserWave has repaired this issue now. I have some new PBS cubes from Bridge and they measure reflection at ~99% and transmission at ~95%!!

Shameless plug: These will be available on the store below tonight

--DDL

[daedal]

any trade up policy?

Haha... doubt it...

--DDL

[Laserman532]

I bought those cubes 1-10-10...i doubt much has changed since then...hmmmmmmm

I would hate to think that bridge would have dumped bad stock on this illustrious forum member

may be marc or bridge will chime in and explain the difference between mine and daedals (if any)

I'll see if i can get a red running and do some testing of my own...in all honesty...the test procedures and results there of, in this thread (and no offense to anyone) are vague at best...not a very scientific approach.