Please help identify for repair and modding...

Recently I bought some pointers from a manufacturer in China.
It seems to me they are different from most other pointers since the crystal is richt on the diode, without any optics in between.

I fried a diode and want to replace it with something more powerful.
I tried a standard 5mm 250mW diode, but the crystal doesn't do a thing then.
Guess it needs lenses.





Can anyone help identifying the used diode so I can find a good replacement?
Any info is welcome!

Regards,
Marcel

What color does this assembly output? If it makes green, the diode is probably a 1064nm device since there does not appear to be any Nd:YVO4 crystal (which is what a 808nm diode pumps to get 1064nm, which is then doubled by the KTP to get 532nm). That slice of optics in the end piece could be the KTP.

If it is indeed based on a 1064nm diode then I am very excited to see these become affordable, this means a whole new generation of small / short length, cheap (albeit low power, that's OK) pointers coming. And the need for an IR filter might be eliminated due to the low power with suitable coating of the other optics...

Thinking it must have poor divergence - unless there is a collimator lens downstream of what you have shown here.

What does the driver board look like? Post a picture of that, OK?

All in all - verrrry interesting. Unless, of course, it is a cheapie red

I agree it does seem very interesting! He did mention using a 5mm 250mW diode, which would indicate it might just be a green laser!

It's very hard to tell what I'm looking at, though I see there might be a KTP in the piece pictured above the diode. it's also possible the enitre crystal set is in that piece as a hybrid Nd/KTP rig. I also don't see any collimating lens, so I can only assume there is another piece?

Anyway very interesting stuff, I've not seen a setup quite like this before...hopefully it's not a red laser

Hi guys, I'll help you out

YES! It produces green.
Of course there is more than tis diode and crystal. There is a brass tube with two lensens as a collimator. But that's all.
I pushed out one of those crystals and it consists of two pieces, one layer I would say 'pink' and a bigger piece that is normal clear transparant crystal.
Greenish coating on both ends.
There is no IR-filter anywhere in the set, so maybe the coatings are doing the job? (Or it just radiates high amounts of IR )

I have tried to make some pics of the board.








And here you see what they look like....

I have had 10,20,100 and 120mW but I cant really measure the output.
The 100 and 120mW are awesome!

I tried to align the crystals on a few of them and a 10mW laser produced a guessd 30-40mW then!

This 'aligning' I tried through rotating the bus that is holding the crystal set, but while rotating it, of course it comes in or out (it's screwing in and out).
I then screwed it in too far, crusching the diode. My way of 'screwing up' :laughing:

So, the square hole you see is actually the crystal set. The complete unit you see on the picture with the laserdiode in place, consists of only 5 parts:

Small tube, with crystal set inside, bigger tube where the diode will fit in, and the bigger ring, keeping the diode in place. (and a tiny little spacer ring, on the back of the diode, but that doesn't do anything special).

Hope this helps!

Regards,
Marcel

Sounds indeed like a hybrid crystal, and if it doesn't lase with your 808nm pump, it could have separated. According to sam's laser faq, DPSS lasers without lenses betwen the diode and crystal set are about 1/2 as efficient as ones with lenses. Also, diodes that aren't enclosed are very sensitive to any particulates that may fall onto the light output section, causeing them to eventually fail, so they should be handled in a cleanroom or HEPA hood.. or be very liberal with the dust-off can!

If you have more of these, maybe take the diode/driver off a working one and test to see if these crystals still lase. It's possible that they just need to be driven harder. What current does a working one draw from the batteries?

It sounds like the coatings are acting as the IR filter as normally the IR filter is greenish in colour. Definately sounds like a hybrid crystal and that they have tried to make it as compact as possible. First time I've seen one that used coatings instead of an actual filter in place though.

Interesting setup, when you replaced the diode as it an open diode or a sealed can? If using a sealed diode you might need a lens, however 250mW is enough to get the crystals to lase. Though your 120mW version is probably using a 500mW diode.

That driver board is extremely simple, it APPEARS that the PD connection of the IRLD is being used, which implies that these are constant IR power. Interesting. If this is the case, it could explain why your replacement LD did not work; if the PD polarity is reversed, the driver board may not turn the LD on at all.

Did you measure the LD current with the replacement diode in there? If it was something like 200~300mA then I would guess it was lasing OK.

The original LD itself seems to have a fairly large block of stuff at the output facet, perhaps this is the Nd:YVO4 resonator?? Building it onto the LD would be an interesting integration approach, and help to heatsink that bit of crystal as well.

I agree with dr_lava that the non-hermetically sealed LD (if you didn't pull the can off) is prone to failure from environmental contaminants, even humidity. Seems pretty lame, unless that is a chunk of Nd:YVO4 on there, in which case it is a non-standard assembly and the top half of the can (with the aperture and window) might still be "under development".

What's the price point of the lowest power unit? Just curious and if you would rather not say, I understand...

Uh ... Wurf ... please re-size your pics to max 800pixels width ... they cause horrible scrolling :green:
thanx.
bernhard

Corona:

I think the replacement diode I used did turn on. I use an infrared-camera to check. When aimed at a near surface I can see a rough line being emitted on that surface.

The original LD is as shown, so I didn't pull the can off.

A 5mW costs about $32 FOB.
20mW does $43 FOB

I used new pictures of the board. I found these somewhere on the net. They are identical to my boards, exept the board isn't glued to the LD in my lasers.

I also see a difference in the beam characteristics of this lasers.
At the aperture, the beam is SO narrow, even a 20mW produces smoke when aiming on I.E. leather, at about 3 inches. But at 20ft the dot has diverged to 1/2 inch.
This week I received some 'normal' pointers, built more commonly, and I noticed the beam was about 3mm at the aperture. These lasers didn't diverge as much as the ones we are talking about.
So, in short, my lasers do diverge a lot, but they start off very narrow.

What is the distance I should keep between the LD and the crystal set?
As you probably see in the pictures, I can move the crystal in and out by twisting. This is how I destroyed it. Turned it in only a little and then apparently crushed the LD.....

I don't know if I explained things well. English is not my native language.
I'm from The Netherlands.