Test of diodes in NUBM08 block one by one

[Light superglue]

From many tests with single laser diodes discussed here we know that the LDs with G-ball of even the same type can slightly (or not) differ in power, wavelength and quality of collimation by attached G-ball.

Since 2 years ago when the 8LD blocks have appeared on ebay I wanted to know if the LDs inside one block would be similar or not by all or some of these properties. But as far as I know no one has checked this and posted on LPF before.

So recently I have received a block of NUBM08 from a Chinese colleague who bought in taobao (kind of Chinese ebay) for pretty cheaper than prices in ebay here.

Testing each of 8 LD one by one with a shaped Teflon LD socket at 500mA I found that the collimations of these were pretty different changing from a rectangle spot to a good line at the wall 5m away (but still not as good as this line would be with G-2 lens).
The output powers of all LDs, however, were pretty close and in range of 6.0-6.9W at 4.5A.
The sum of outputs would be 36W at 3A and 51W at 4.5A for the whole block.

Then I did a kind of “WL tests” by passing the beams through Blue–Blue dichro which lets through up to 450nm but starts to reflex the beams from 460nm up.
Here most of the beams were passing with 80-97% efficiency and only one of them (from the weakest LD which gave 6.0W output) was reflected at 72%.

This is in agreement with what DTR and other members said earlier that the less efficient LDs usually have higher wavelengths.

 

[deadshadow]

i have 2 nubm08 diodes on my own(3 with one degraded) and i can confirm that the one that is not that strong and even at 5A the output is around 5950mw it has a very high wavelength compared to the other one that does 6w at 4.2A,the beam color looks pretty close to a nubm07, i could have mistaken it if i wasn't sure that is a nubm08

 

[JimK]

Your averages correlate well to DTR's sales ramp images which I graphed at the bottom.

Mass manufacture, especially samples, can be some crazy margins.
I've found LED's (Cree bins specifically) vary like this in color render index, temperature and luminous flux in the same way laser diodes do.

 

[GSS]

Nice individual block comparison.. Surprised RedCowboy didn't chime in, he lives for this stuff

 

[Benm]

Interesting to see how much variation there is in the output pattern of these diodes really, even in a single block where i'd expect all diodes to be from the same production batch.

I guess it doesnt really matter much when used in a projector or something like that, but if you want to make a handheld single diode laser out of it, the difference seems huge. Of course it's already hard to get a decent beam out of these multimode diodes, but it seems like each needs different corrective optics to stand any chance.

 

[Light superglue]

Hi Benm,

Me too expected to find that the LDs in a block would be from same batch, so easy to combine by usual means but it seems that either Nichia blocks are produced by a subsidiary from loose LD bins or the LD batch QC accepts margins like these ones...

Now I want to check how well parallel the 8 beams are placed but will not get the PCB (they are also sold in taobao) before summer. From parallel beams at least I could make a close range burner if all beams focused at same spot (like Death Star of LPF member with nickname anselmo... YT video).

 

[Benm]

I would expect them to be pretty parallel, otherwise the projector would not really function, would it?

Then again given the big differences in divergence and wavelength from those in a single block i would't be totally sure about it.

Apparently there is a fairly wide 'good enough' criterium for these blocks, which makes me wonder how good the finished projectors actually are. To be honest i have never seen one in operation, but this makes me wonder how uniform the white balance across the image is and such. Then again with projectors people rarely measure that at all.

With things like monitors color calibration on different parts of the screen are easily done with things like the datacolor spyder, and review websites will often talk about that aspect as well. With laser projectors it is a lot harder to do: those sensors aren't suitable and it also depends on how color-uniform the surface you're projecting onto actually is.

 

[RedCowboy]

Maybe some of the blocks we can buy without a PCB attached are rejects due to mis matched lenses ?
Although I know there are packs of blocks with no PCB.

I have seen other pics of the blocks running and the beams looked identical, and the spots all clumped together as they diverged.

I may have screen shots, but the images should be here somewhere unless photosucket lost them, I think it was a 05 block.

I wish the blocks of NUGM01 diodes would come down, 2 of them (16) diodes in total would make a neat long range green spotlight project.

New Blocks without PCB

 

[Benm]

There is always the chance them being rejects unless you have a source that can verify they are not.

I'm not really sure if the PCB being installed or not is any indication, but it could be. Perhaps they use some jig to give the blocks a quick test before mounting the circuit board, and if one of the diodes is a dud or something like that they reject the whole block.

That would only be a big problem if you wanted to use the block as a whole though, if you could get blocks with 7 out of 8 diodes perfect and one dud for half the price of a qc passed block it would still be a good deal.

 

[Light superglue]

When my chinese co-worker asked the seller if he had a block with PCB the answer was that "we only sell brand new blocks, not the used ones".
And other sellers from taobao (who were advertising blocks with PCB) answered that the pieces were not available.

I find it reasonable: when the prices are 20-30% lower than on ebay, the availability may be not granted.

BTW they have certain NUGM03T blocks there which look different from 01/02 we are used to see on ebay. 525nm but nothing special in power compared to older ones...
https://s.taobao.com/search?q=nugm0...2227oh.d100&from=sea_1_searchbutton&catId=100

 

[Benm]

Yeah, all sorts of options available for either with or without a pcb.

Without could mean perfectly good but never installed into a projector, or a reject from a testing jig before the pcb is soldered on.

With the pcb could be removed from a perfectly good projector, qc passed units taken before assembly, but also units from defective projectors that have been returned by customers.

The latter is a likely source to be honest, but a defective projector does not mean that there has to be anything wrong with the laser ofcourse, perhaps it just had broken hdmi connector or some other fault unrelated to the light source.

 

[RedCowboy]

NUGM03 Interesting. I like this design.

The Chinese hobby market is going to make a lot more possible/more affordable, this is a good thing.

I have seen the bags full of new blocks for sale, I thought all the GBalls would be the same, strange that there not, I need to see the rest of the phosphor light engine.

Looks like they are selling the PCB's to make use of the blocks too.

How much is 5500 Chinese Yuan in USD? Ok it's about 850.00 USD

 

[Alaskan]

That looks much easier to deal with, except G-Ball lenses

 

[deadshadow]

this new nugm03 diodes look to have identical gball lens with nubm08.anyone can confirm a degradetion or death on a decanned green diode?those might very well not degrade as are not the same as 4-7w blues.i do have a decanned nugm01 on my build,already passed a month without lossing any power,those could act like the older 1-2w range blues that wasn't degrading when deccaned for any reason.

 

[Alaskan]

Where can I find the specs on the NUGM03?

 

[RedCowboy]

Lot of info on this Chinese site, look at what 2 blocks ( 16 ) diodes shine into, it appears to be very short range, from there into the back side and then the phosphor, I have not found the phosphor yet, but new blocks may be coming, those thin blocks could be used for all the GBall diodes, maybe this is why the GBall diodes are falling in price. ( NEW ) 05 blocks for 220.00 and single 05's ( NEW ) for 24 dollars, I hope we see some new diodes as well, but I think the old high security block is going away.

The NUGM03 you can translate the text but I can't seem to copy and paste the translation, it says newest and 0.1w increase and 0.4a increase over nugm02 at 525nm and they say brightness will look a lot brighter.

此款主要用于激光彩色投影仪的显示光源,目前是市场上绿光管里最高功率的.相对于02T功率提升了0.1Ｗ，波长增加了5nm,电流增加了0.4A,亮度就会感觉亮了很多.

Here is the NUGM03 link >>> https://item.taobao.com/item.htm?sp...ia4SNm&id=565007134010&ns=1&abbucket=8#detail

----EDIT----

Look at this, the price just can't be right.

https://item.taobao.com/item.htm?sp...720&pvid=7fd9c44c-2bec-40b0-8b6b-75a23a3575a3

Price for this also can't be right.

https://item.taobao.com/item.htm?sp...334&pvid=4397edf9-f0e1-4938-a17a-c64b9b2861a6