Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 23

Thread: opsl - when did these happen?

  1. #11
    Join Date
    May 2007
    Location
    Authentic Asian food area of SoCal
    Posts
    2,460

    Default

    Quote Originally Posted by buffo View Post
    Do you have a power meter? If not, do you have a wild guess at what the output power might be? Just curious...
    Sadly, I don't have an LPM. At rough guess, I would say this is hitting about 50~60mW. I am driving at 600mA. The pump diode can go higher, I don't know how this will affect the lifespan though. I saw on LPF people pushing these to 1A but I don't know that I will get that high. The green is indistinguishable from 532nm DPSS. If these units work well, I will have my yellows and oranges back!

    Another thing to note, the bare OPSL modules have a super thin beam at aperture with high divergence; 4+ mRad. These RGB modules look like they have either a telescope in front of the unit or some kind of grin assembly (see pic). Either way, the divergence is still not great but much better. Without doing any math, to my eye, it looks to be about 2 ~ 2.5 mRad. Very usable but since the assemblies are so small, there is no way to clean that up without affecting the other diode beams

    Click image for larger version. 

Name:	Screen Shot 2019-05-14 at 10.15.56 AM.png 
Views:	7 
Size:	898.6 KB 
ID:	55480

    Interesting about the thermal sensitivity... Would not have guessed that!
    Agreed. It was so touchy. I don't know a lot about OPSLs but I am pretty sure the heater is for the SHG crystal. The sensitivity seems to be limited to the crystal/heater though, not the ambient temp of the laser... e.g. placing my thumb on the top of the unit for a few minutes didn't affect the output. So, modulation might not be too bad although this is probably due to thermal lensing. I didn't think thermal lensing would be that extreme at these "lower" power levels, if that's what is happening.

    I ordered 5 of the RGB units. I am going to get the red and blue working on this one and then I am going to get the others going. I am curious if they are all this picky or if I just managed to pick a winner!
    Last edited by absolom7691; 05-14-2019 at 20:23.

  2. #12
    Join Date
    Feb 2007
    Location
    Fort Mill, SC USA
    Posts
    1,383

    Default

    Thank you for posting this information, Absolom! My plan was to make mini projectors out of the RGB units and beam bars from the green-only modules, but based on your findings, Iím better off just sticking with more powerful single mode diodes. Poor divergence, picky power and difficulty aligning just doesnít strike me as good candidates for projectors. I suppose when things sound too good to be true, they probably arenít. 😟

    David
    "Help, help, I'm being repressed!"

  3. #13
    Join Date
    May 2007
    Location
    Authentic Asian food area of SoCal
    Posts
    2,460

    Default

    Quote Originally Posted by dkumpula View Post
    Thank you for posting this information, Absolom! My plan was to make mini projectors out of the RGB units and beam bars from the green-only modules, but based on your findings, Iím better off just sticking with more powerful single mode diodes. Poor divergence, picky power and difficulty aligning just doesnít strike me as good candidates for projectors. I suppose when things sound too good to be true, they probably arenít. 😟

    David

    I am going to test the other units when I get home but yeah, it's looking that way. Here is the spec-sheet for those who might be interested. Looks like I might be over-driving mine by about 150 mA which might​ explain a little of the instability. It also shows that most of the IR is filtered with the exception of a few mW, which is good. In over-driving it, I am sure it was a little higher, that's probably what my camera was picking up. I might step it back a bit.

    http://optoengine.com/images/Documen...sers/PL530.pdf
    Last edited by absolom7691; 05-14-2019 at 10:44.

  4. #14
    Join Date
    Apr 2009
    Location
    North of Jackson Michigan USA
    Posts
    259

    Default

    Ah, this should work well for lumia!

    ...Mike
    Runs with Lasers

  5. #15
    Join Date
    May 2007
    Location
    Authentic Asian food area of SoCal
    Posts
    2,460

    Default

    Quote Originally Posted by clickamouse View Post
    Ah, this should work well for lumia!

    ...Mike

    They may just be good for that. The alignment on the first one is off. Not by a lot but enough to make it unsuitable for images and beams for anything beyond 10'.

    On to the next one... Hoping the alignment will be good on one of these.

    Hard to see in these pics but the red is way off. The green and blue are close but also off. I'm going to see if I can tweak the steering optic.
    Click image for larger version. 

Name:	IMG_20190514_175524579_LL.jpg 
Views:	0 
Size:	2.78 MB 
ID:	55482

    Click image for larger version. 

Name:	IMG_20190514_175332658.jpg 
Views:	2 
Size:	3.07 MB 
ID:	55481

  6. #16
    Join Date
    May 2007
    Location
    Authentic Asian food area of SoCal
    Posts
    2,460

    Default

    Candidate #2... Alignment off. This one had way less beam trash than the first and seemed a little more stable. The heater was still sensitive (this one liked 60.5 mA) but I think with a rock solid constant current power source, it would modulate well. As for the alignment... it sucks because it's only off by a fraction of a degree but enough to be unsuitable for images.

    So, good for images/beams; no
    Good for lumia; Hell yes! The alignment is off by so little that a well placed torture tube yields amazing color blending. Because of this and the small size, I may just have a place for these yet!

    Unfortunately, a phone camera fails to capture the creamy blend of color.
    Click image for larger version. 

Name:	IMG_20190514_203650518_LL.jpg 
Views:	6 
Size:	2.76 MB 
ID:	55484

    Click image for larger version. 

Name:	IMG_20190514_203501249_LL.jpg 
Views:	4 
Size:	3.06 MB 
ID:	55483

  7. #17
    Join Date
    Apr 2009
    Location
    North of Jackson Michigan USA
    Posts
    259

    Default

    Excellent!
    Actually, for lumia, you want the beams to non-colinear.
    You spread them out so they hit different places on the diffraction media.
    Otherwise, you get 3 colors of the same pattern - not very interesting.
    In my RGB Lumiators, I first get them collinear, then nudge the steering mirrors so that they are parallel but offset from each other.

    HTH...Mike
    Runs with Lasers

  8. #18
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,772

    Default

    Quote Originally Posted by absolom7691
    the divergence is still not great but much better. Without doing any math, to my eye, it looks to be about 2 ~ 2.5 mRad. Very usable but since the assemblies are so small, there is no way to clean that up without affecting the other diode beams
    Could you simply cut the top edge of the aluminum frame off, eliminating the bounce mirror and the dichros? Then you could correct the green beam using whatever optics you wanted and then re-combine them further down your optical path? I mean, sure, it won't be as compact, but in theory you could get that beam divergence way down if you wanted.

    I am pretty sure the heater is for the SHG crystal.
    Almost certainly. Although it's still very interesting that it's so temperature sensitive. I think you're right, it's probably a thermal lensing issue and not just the efficiency of the doubling crystal itself changing due to temperature. (If memory serves, the optimal temp for KTP is around 70 C...)

    Adam

  9. #19
    Join Date
    May 2007
    Location
    Authentic Asian food area of SoCal
    Posts
    2,460

    Default

    Quote Originally Posted by buffo View Post
    Could you simply cut the top edge of the aluminum frame off, eliminating the bounce mirror and the dichros? Then you could correct the green beam using whatever optics you wanted and then re-combine them further down your optical path? I mean, sure, it won't be as compact, but in theory you could get that beam divergence way down if you wanted.
    This is true but I was hoping for something this small, with "fixed" dichros that would't drift as much as larger kinematics/dichros. The collimation for the red and blue diodes are also set similarly and can't be adjusted. I am not "too" concerned with the divergence as it isn't that bad. Besides, this is for a living room projector so I doubt the screen would ever be more than 20ft away.


    Although it's still very interesting that it's so temperature sensitive. I think you're right, it's probably a thermal lensing issue and not just the efficiency of the doubling crystal itself changing due to temperature. (If memory serves, the optimal temp for KTP is around 70 C...)
    I still need to test the modulation. It's very possible that the modulation will be rock solid even though the SHG temp is fairly critical. I am wondering it it's because the laser needed to be small and as a result, the crystal is a tiny chip that is very susceptible. I have a bit more testing to do but I think these are going to be relegated to lumia use.

    As far as alignment, the "steering" optics for the red and blue diodes are ball/socket lenses that are glued in place. I am pretty sure I will destroy one by trying to adjust it but if I can break the adhesive loose and try to adjust it, I might be able to get these lined up. I'll try on one of them and see how successful I am. It's most likely going to fail but unless I can align them, they are destined to just be rgb lasers for a lumia at this point. If bought separately, I couldn't get an rgb diode set with dichros for the same price. So, definitely not a loss.

  10. #20
    Join Date
    Nov 2014
    Location
    mid michigan
    Posts
    781

    Default thermal lensing?

    I don't think I have come across this term with a small laser so what does the thermal lensing do? does it drift with temp?

    Thanks

    The all-knowing "although sometimes un-knowing" Dragon of PL


    Draco
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •