Extreme Lasers... good or bad?

[MichaelH]

If anyone's interested in buying mine, I've got my replacement GBS-100 going on eBay here.

http://cgi.ebay.com/ws/eBayISAPI.dll...MESE:IT&ih=002

The one it replaced was only doing about 30mW but this one seems (my meter only does 60mW) to be putting out over 80mW, accounting for enough divergence that my meter doesn't top out.

[allthatwhichis]

I wanted to drag this one to the top for a moment... I got my 50mW blue dpss form extreme a couple of days ago and for not having a meter I am very pleased. I paid for two day shipping and got it right on time and have had all my email answered in about a day. 3 or 4 now. I also have a GBS-100 and questioned it's strength until I saw a picture of a 300+mW that looks A LOT like the GBS sitting next to a 50mW blue that looks a lot like my 50mW blue. To me the picture looks like what I pictured my GBS looking like in comparison to my 50mW. ops: Guess I was wrong. I still plan on getting both of my lasers from extreme measured before I leave him feedback on eBay for the blue, but, and this may be because this time I spent twice as much, the customer service so far from Jure has been acceptable. We'll see how the lasers measure...

[nono shen]

Laser is a sensitive thing , it will has some different when the temperarure and enviorent changed, though it is the quite good laser before it leave factory , but when they arrived to a new place , when the different current , temperatrue , voltage change , maybe a few will has some difficulties , it is so stange ,I don't know why .

So laser is a sensitive thing , we should value them and maintain it clearn and keep the operation temperature .

Nono Shen :P

[eyceage]

My latest thoughts on the GBS-100 are this:

If you want stable output, turn down the pot.

I think part of the reason these things are so unstable is that they're being pushed to near their limit, and the TEM mode(s) being used to achieve this power are prone to fluctuation. With goggles, I could easily see the beam structure, and how it's shape changes with pump power.

As they come, the beam shape is like 3 or 4 "lines" packed together. The brightest "line" is usually the center one, but sometimes one of the ones closer to the edge is the primary. As you turn down the pot, interesting things happen:

First, the brightness shifts from one line to another, and total power goes down gradually.
Suddenly, one of the lines disappear, and power goes up again.
Then, more regular behavior until each line (TEM mode?) disappears, accompanied by a small power boost.
When only two lines are left, power will become very dim (approx 15mw) right before it snaps into single mode and becomes very bright again (~50mw)! The beam shape is now very round, diameter is small, and I would guess that coherence length is much better.

So, it's interesting that turning down the pump power sometimes increases output!

I'm keeping my 80 turned down to 45-50 for nice, stable output.

[allthatwhichis]

:!: :!: :!:

Awesome, what I really want to do to my gbs it to turn it down to mix with my 50mW blue. Any chance you could take a picture if where the pot is?

Here are a couple of pics of my gbs' power supply with no cover...





Is it that blue box in the upper right corner, relative to screen, with the flathead screw in it? If yes, which way do you turn it and for how long? I turned mine a few turns in each direction with no change... I didn't go toofar and made a mark and counted the turns so I could get back to the was it was/is when I opened it.

[jkaiser3000]

That blue box is a pot, but I can't say if that's the one eyecage meant. Your power supply is completely different from mine (I have a GBS-80 though). Mine does not have a pot that I can see. Not that I mind though, that laser is rock solid and it only starts to mode hop when I try to blank it at around 1KHz or more, from a home made square wave generator. Haven't tried the signal from a DAC, yet

[allthatwhichis]

Well... I just killed it... ops: :? Not sure what I did, one moment it was on and I was turing the pot, the next it was out... :cry:

[jkaiser3000]

Sorry to hear that. Heve you tried turning the pot back to its original position?

That's why I'm glad mine doesn't have a pot. I don't want to mess with it, and I know if it had one, I'd be really tempted to tamper with it :roll:

Anyway, how much did you turn that pot?, one turn?, more?. I don't think you could've killed it by just a bit of turning. However, if you overdid it, things could be different

[allthatwhichis]

I was turing it a lot. In 5 to 10 turn increments. I started slow, but nothing seemed to happen. I turned it back and no good... The day before it's beam looked like it was separating into a beam and a smear anyway at about 8 to 10 feet. :? I'm not nearly as impressed with my green from there as I am the blue. :roll: I may just try to find a little 50mW green, hopefullly analogue to replac it with. It WAS too much for the projector I am building. Would've been nice to have intergrated it into something I could have sold though...

[eyceage]

That sucks.

That is the same pot I was using. I'm really suprised you didn't see big changes as you turned it. For me, I could see power go up with about 2 turns (I *think* clockwise), and had about 6 turns the other way until the laser was near off. I even pushed it pretty far in the increasing direction and could easily get 120 or so mw output (I was afriad to go any further).

I wouldn't be suprised if each one behaves differently, but I would have expected you to see some better results.