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40-50W blue laser from tightly packed parallel 08 beams

RedCowboy

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How hard are you driving your 08 block ? That is what is the output from your power supply going into the 8 diodes ?
I am curious how many watts are you putting through the PBS cube from techhood because I did not think they would take tens of watts ?

Are you still planning to do this with a nubm44 block from a V1 using G2's ? If so I would be interested to know how much a PBS can take.


--edit--

I see 1.99a on your power supply display, so if you are driving two strings of 4 in series parallel @ 15v and 2a then each diode would be getting 1a making 1.1w at each Gball for a total of 8.8w raw for the block and maybe 7w after losses in your final beam ? or are you driving them all in series at 32v and 2a ?

I have under driven GBalls before to get a smaller/tighter beam but I have not attempted to knife edge from GBall intact diodes, it's cool to see you have made it work but I am curious about your final beams wattage, can you share a result please ?
 
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brianpe

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Great work. I didn’t know you could get knife edging that tight. It looks like your cylindrical lenses are about 1-2 cm from the collimating lenses. Was that where you got the tightest beam? When I’ve used cylindrical pairs I‘ve had to butt them as close to the collimator as possible to keep the divergence tight.
 

Light superglue

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Brianpe, yes, they are 1 cm away, this is needed to keep space for temperature sensors on the block. I do not think that a 1cm separation would make a huge rise in divergence.

Red, did you look at the original thread? I always connect all LDs in series, never in parrallel, because less current means less losses in the curcuit. 32V at 2A make 64W load. But with 12V, 15A max. rated power supply at the moment I cannot make more than 3.3A current at 35V.
I am replacing it by 24V supply in order to make the block glow at full power at 4.5A current.

About v1 light engine with 7 G-2 on top I did proof of concept and it seems to work but I would post this in another thread due to different design and many pictures to follow.
 

Light superglue

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Now I have replaced 12V AC-DC adapter by 24V one and can reach 4.5A current through all 8 LDs in the block.
Since my walls already have many marks, I wanted to protect the wall by a thin PTFE sheet (thickness might be 0.2mm) but it did not help much - after half a minute the sheet and wall behind were burning again. Then I replaced it by a thicker one (0.5mm) and this protection has been doing well.
The beam spot at 4.5A is still the same 2cm square as before at 2A but the beam itself is very bright and well visible even at day. The spot is very bright even if shot through OD6 googles and my camera can hardly see the ruler under such a brightness...

About PBS:
I mesured its temperature by a tiny IR-thermometer holding it very close to the top of the cube.
Another NTC thermal sensor is attached to the N. block.

So if current of 3A runs for 5min, the T on the surface of the block stabilises at 50ºC with HS fan working and PBS surface reaches 65ºC (very hot to touch).
Then I wait 2-3 min untill block is down to 30ºC and PBS to 35ºC (there is no fan cooling it) and start 4.5A current.
In 1 min block is 50ºC, PBS 53ºC.
In 2 min block is 60ºC, PBS 62ºC. Here I stop and wait again.

I have repeated it twice, and do not notice any visible damage to PBS cube. Maybe they have to be of special quality for hours of constant working but for 1-2 min the Techhood one seems OK.

23 (4.5A).jpg24 (4.5A).jpg25.jpg
 

RedCowboy

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Great, I am glad the cube is holding up, when I talked to OPT in Poland they said I would need a special made cube for over 10w but they may have been thinking about continuous duty.
 

Light superglue

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I wonder what could be the temperature inside of the cube. What I can mesure by IR thermometer is on the surface.

Question:
When PBS suppliers say about damage threshold what do you think they mean: damage of the beamsplitting layer inside, glass material itself (from unequal heat distribution because glass is not a metal to evacuate heat to surface quickly) or AR coating on the surfaces?

Anyway yes, for continuous duty it might be better to think about PBS cooling as well - something like putting it steadily on a HS with small fan and adjusting the 2nd beam direction by moving the side mirror.

Thorlabs also has polarizing BS plates (which have bigger surface compared to cubes) but very expensive and not for 450nm.
 




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