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Kaidomain 50mW CR2 - inital review

IgorT

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Bob..

Is it possible, that you just saw the bottom of the crystal through the square opening?
It would look green from that side.


Maybe this diode just has a much better beam profile, than the 9mm in the DX200. There the IR comes out as a very long stripe, not even a hint of roundness in it. Is it an open can?
 

bob12345

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IgorT said:
Bob..

Is it possible, that you just saw the bottom of the crystal through the square opening?
It would look green from that side.


Maybe this diode just has a much better beam profile, than the 9mm in the DX200. There the IR comes out as a very long stripe, not even a hint of roundness in it. Is it an open can?

I'm not sure to be honest. I'm just describing exactly what I see :)

The IR diode is more than an open can. As in the matrix - THERE IS NO CAN!!!
 

IgorT

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Anyway, i just spent a lot of time cleaning and adjusting the lasers. The best one didn't get worse. It was all bad contacts. It is still the brightest, when the contacts are good.

There are so many places, where the contact can get bad in this laser tho.. Cleaning it like Knimrod suggested is the best thing to do. I even had to swap the switches between the first and the best one, because it hardly had enough place for the battery and the switch didn't want to go deep enough into the tail cap. It was pushing at the board too much, and had a bad contact with the cap. Once i swaped them, they both go in equally deep. It's weird, but works.

Since they're not regulated, every tiny resistance changes in any one of the contacts affect the brightness a lot. Something, that will get much better with the driver replacement.


I also noticed a tiny bit of mode hopping in the best one. The spot becomes more egg shaped but doesn't split. It is related to the pressure of the battery on the PCB. The fact, that the spring is almost missing in this one, doesn't really help much.

It's not really bad, and the brightness isn't affected by it. Using the Nova Lasers standards, it still falls under "good" when it is the worst.


All in all, i like these lasers very much. Even with the few problems they have, they are amazing lasers for this money. At first i was planning on selling one or even two, but now i'm keeping all three. My friends will have to order their own...
 

zoriahnyc

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Is anyone else having the following issue with this laser: It comes on quite bright and then quickly dims to nearly half the initial blast of light? I have tried putting solder on the switch contacts and peeled a bit of the glue off the copper barrel, but neither made any difference.

This would be a really great little laser if it would stay at the peak brightness for more than a split second. If it is capable of that output, why would it not remain?

I have tried Lithiums and Alks...both are about the same as far as this issue goes.
 

pwnstar

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im sorry if im repeating this but...
is this laser pulsed???
i used it with a spirograph and i see a dotted line but no dotted line with my DX30
ill post a pic l8er
 

IgorT

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zoriahnyc said:
This would be a really great little laser if it would stay at the peak brightness for more than a split second.  If it is capable of that output, why would it not remain?
I have three, and they all behave slightly differently.

One of them is very powerfull, but i noticed it sometimes drops a bit, and it is a contact issue. If you touch the button very slightly, when it's on, and see the brightness change, you should clean the insides with something abrasive, and maybe solder the switch in place, so it can't move when you press it, and move itself and the battery down the barrel.


Otherwise, it could be an issue with heat. My other KD50s don't come on at full power. You can see the brightness increasing but it happens very fast. If i leave them all on after that and look at them later, i can see the brightness slowly decreased, but differently in each of them. In some of them, adding some cooling can help, while in others, it actually decreases the brightness.


Since these have many spots, where there can be a bad contact, and are also not regulated, it can be hard to pinpoint the problem. You should start by cleaning all the metal, where the parts touch.


If it is the diode changing it's wavelength with heat, you should provide some additional cooling at the lower end of the module. The same goes, if the crystals actually drop in efficiency with too much heat.

I've seen the crystals behave very differently, even with the same type of laser. Some liked being cold, others didn't work cold at all.


In the worst case, it could even be an alignment issue, as this is exactly what i observed when fixing my DX200. It would come on very bright, and immediatelly lose brightness. But it goes away, if i find the right alignment.

You should check the spot through a magnifying glass. If the beam splits in two it also loses much brightness. This would be the hardest to fix, but the KD50s seem to be much less sensitive about this. You would have to remove the glue and turn the diode (by turning the driver), to get the most brightness out, then glue it back in place in that exact position.. It might be usefull, to mark the original position.

There is a chance, you could ruin it with this, so only attempt it, if you're sure you want to risk it, and have the patience to fix it.
 

Benm

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pwnstar said:
im sorry if im repeating this but...
is this laser pulsed???
i used it with a spirograph and i see a dotted line but no dotted line with my DX30
ill post a pic l8er
I don't think mine is pulsed, at least not in any way that i can notice... line seems continous even if i swing it around by its cord. I dont see any reason why it should be pulsed either, circuitry doesnt indicate towards that at all.
 

bob12345

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Yes, very odd... My laser is definitely not pulsed.


OK, I opened the laser up yet again. There is no collimating lens or fast axis between the diode and crystal. The proper schematic is here:



So maybe it was a miracle I managed to line it up ;D. Either way, the beam is now VERY solid and yesterday I actually tested it at night, twice as bright as before and the beam is like a lightsaber.

On the other hand - when the batteries are on their last 30 seconds, the laser starts to behave very strangely. It starts to modehop like crazy and emit IR (I accidentally looked near the aperture and saw the red glow).

As far as I can tell, these lasers have no IR filter. In addition, IR can leak from the diode into the KTP cavity, without running through the 1064 crystal - this is not good at all. If there is any way to block the IR there and then (huge hole for it to go through) then I'd love to hear it. Maybe some kind of mirror, which will reflect it back and forth into the crystal.

It does seem to be the standard NewWish style assembly.
 

IgorT

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Yeah, that is odd. I just tried with all three of mine, and they don't do that.

Could your laser perhaps be vibrating somehow, on the spirograph? What are you feeding it with?
 

IgorT

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bob1122 said:
OK, I opened the laser up yet again.
How did you manage not to lose this great alignment, while taking it appart again? Or did you have to re-adjust it?

My DX200 made me very worried about ever taking another green appart completelly. But if these are not that complicated to align, i might just try it, to get the most out of them..


bob1122 said:
On the other hand - when the batteries are on their last 30 seconds, the laser starts to behave very strangely. It starts to modehop like crazy and emit IR (I accidentally looked near the aperture and saw the red glow).
If this only happens with very empty batteries, then it's not such a big problem. Many of these cheap lasers start doing this when the current drops too low. I haven't even tried running one of mine so long, that the batteries would be completelly empty. The brightness starts dropping very soon, so i just recharge as often as i can.



My AMC boards have been shipped, so i should have them in about a week. Can't wait to start modding these.
 

bob12345

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As far as I can tell, it's not too hard to line this laser up at all.

It will give off that weird "wave" pattern when it's not correctly lined up (I don't know how to explain but if you have a mode-hopping laser it usually casts a flat cone sort of shape on the wall in addition to the two beams). With this, you can just rotate the diode/driver until it's all lined up. You set it up by taking the brass laser module + driver out, screw the brass inner ring into the case (the side that holds the battery, not the side that holds the laser) and then rotate the diode+driver gently and keep testing by contacting the driver spring and brass housing against their respective spots.

Right now I'm very impressed by this laser, it's like a lightsaber outside at night and it definitely was not this bright when I recieved it. Now I don't have to even try to look for the beam, it stands out so much. How much intensity is required to sting the skin though?

Oh and good luck with the mods!
 

pwnstar

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IgorT said:
Yeah, that is odd. I just tried with all three of mine, and they don't do that.

Could your laser perhaps be vibrating somehow, on the spirograph? What are you feeding it with?
hm im not sure but ill try again when i get home.
the laser is running off a Rechargeable CR2 around 3.4V
maybe its the spirograph
i dont notice any difference holding the laser still. it still has a nice solid beam at night =P
 

IgorT

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pwnstar said:
maybe its the spirograph
i dont notice any difference holding the laser still. it still has a nice solid beam at night =P
Try drawing a pattern on the wall by hand.

If your spirograph exposes the laser to small but hard mechanical vibrations, it could be just a bad contact. My KD50s can lose as much as half the brightness (visually) just by gently touching the switch. Sometimes even more than half. Once i start modding them, i will mount everything permanently, so that it can't move. That and proper drivers (and maybe some realignment if i'm feeling lucky) should turn them into great lasers.
 

Benm

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Looking at the pulse pattern, it seems to be quite consistent in pulsetime, so i'd suspect the driver more than any mechanical malfunction as that would result in a more erradic on/off patern.
 




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