1w 532 nm dpss - did I broke it?

celas · Feb 22, 2015

Hello.
A few weeks ago I've bought a 532 nm 1000mw dpss laser with a defect - crystal was misaligned due to kinetic shock this device received and its output power was down to like 100mw. It came with a funny power supply. This power supply had some jumpers and I thought that connecting them will help (dunno even why I got this idea). After that laser immediately lost 90% of itz already lowered power, permamently - now it glows with full power only for a split second after power up (every time, thos can be repeated with the same result - switch - normal power - barely lasing). I am attaching a link to the video of this contraption recorded by me.
https://m.youtube.com/watch?v=7b5bW2ZYsgQ
Did I fry it, or it's just a Psu failure? How to check it? The pump diode is a 3w c mount with fac lens and it's pretty expensive (i gave 200pln=60 bucks for this stuff), changing the pump diode would cost more. I noticed that after failure, pump diode glows brighter red than before.

crazyspaz · Feb 22, 2015

Kinda hard to tell. You may have blown the diode. What exactly do you mean by "connected the jumpers"? Can you provide better pictures of the power supply, what you connected, and the inside of the laser itself?

Also, at one point you pointed that thing right into the camera- even though it MAY be dead and may APPEAR to not be outputting anything, do NOT shine it into your eyes or the eyes of any other person/thing. The pump diode may still be lasing, but it's IR which human eyes can't see- i.e. you could be destroying your eyes without knowing it. Laser protip #1: never look into a laser, ever, ever, ever.

Cyparagon · Feb 23, 2015

Diode is fine if you get any green at all. Step 1: measure the diode current (if you are unable to do this, this project is too advanced for you).

Hiemal · Feb 23, 2015

Also, it sounds like you're preventing the fan on the diode's heatsink from running properly when you set it down. Try and keep it propped up on something otherwise it'll get too hot, which may be one of the problems you're experiencing.

The Lightning Stalker · Feb 23, 2015

As others have stated, running it with the
cover off like that and looking inside
without eye protection is a VERY bad idea.
What your eyes see as a dim red glow is
actually hazardous infrared light. Even
looking at it from the side like that can
be very bad.

Hopefully you are leaving it covered most
of the time. The tiniest bit of dust on
the optics can really mess things up. It
seems obvious, but I don't know how much
you know about lasers.

Now to me it looks and sounds like it might
be running at the wrong temperature. There
is a TEC inside to regulate temperature and
it is very sensitive. If it isn't that,
then the crystals are probably shot. When
it flashes, do you get a nice dot or is it
fuzzy/smeary?

celas · Feb 23, 2015

Dot looks okay. I decided to disassemble everything and I left only pump diode. I wasnt looking directly (all time through camera). Pump diode INSTANTLY burnt a match but seems like its power is completely random - getting full powee spikes when I touch housing with a screwdriver (sometimes). I am completely sure something isnt right with the pump diode but it isnt the circuit.

Aleksa · Feb 23, 2015

The circuit that drives the pump diode is faulty. Sounds like a ground problem,or current feedback. If you don't know basic electronics,it will be impossible for you to solve this.

celas · Feb 23, 2015

Gonna buy a lab supply and check it. I know basic electronics and more, I just have no equipment

UPDATE: Those 'jumpers' were base and emiter legs of main power transistors. That means I probably destroyed the power supply (it was merged with a driver). Does short circuiting transistor legs immediately breaks them?

tttonyyy · Feb 23, 2015

celas said:
Gonna buy a lab supply and check it. I know basic electronics and more, I just have no equipment

UPDATE: Those 'jumpers' were base and emiter legs of main power transistors. That means I probably destroyed the power supply (it was merged with a driver). Does short circuiting transistor legs immediately breaks them?

If they're MOSFET, they're probably OK (though the gate drive circuit might not be), if bipolar almost certainly toasted if you connected collector to base.

Aleksa · Feb 23, 2015

Shorting them,no. I i don't think that the problem is in the output transistors. I think that circuitry that drives them is faulty or it has no feedback. You might have unhooked something. How about some pictures? Maybe its something simple... Good thing is that its not the diode. For future testing i don't recommend using the laser diode at all. Use a couple of silicon diodes in series to simulate a LD(there is a thread on how to make/buy this).

celas · Feb 23, 2015

View image: 20150222 224813
Photo of driver/psu unit. J1 was the problematic transistor (supplying vdc to diode) j2 supplying to fan. Fan works fine after shorting its psu transistor, diode doesnt

Aleksa · Feb 23, 2015

Are they mosfets or bipolar? Anyhow,if you have a DMM,you can measure the voltage on Gate/Base to see if there is anything there. Also,i would recommend getting them out and testing them on diode test. If they are fine,than its probably the drive/feedback circuit.

celas · Feb 23, 2015

Cant do anything until I buy new mm, one I have is broken. Transistors are probably mosfet because if they were bipolar, after shorting them diode wouldnt even react. Guess just gonna buy lab dc supply to be sure

celas · Feb 23, 2015

UPDATE: Pump diode glowing at low current (driver from 200mw diode). Doesnt even overload my phone camera nor heats anything. Here is the photo - does it show anything? The laser glows in line (without any optic except built in FAC ) , this means for sure it's fine?http://postimg.org/image/k00ca00jz/
Checked specs of my module - the ir diode is 5000mw max (not 3000 like I've thought)
so this (on photo) isn't even lasing yet?

Aleksa · Feb 23, 2015

Your phone camera has a IR filter. Hope you have some protection glasses, even 100mW of IR is really dangerous,imagine 5000mW... Its not going to heat up anything cause there is no focus,or the material is transparent to 808nm. The diode looks fine in the video. I don't know much how faulty diodes behave,but from my experience,if its dead,it will not produce a high output no matter what. Yours did,for a second. That's why i think its the problem with feedback. You should really not touch that diode anymore until you fix the PSU. If you dont want to use TTL,you can buy (or make) any other driver for that voltage/current that diode requires.

Aleksa · Feb 23, 2015

Also,there is a specific threshold voltage/current for the diode. So its not that suspicious that there is a weak output from 200mW driver. It might require more than your giving it.

1w 532 nm dpss - did I broke it?

celas

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crazyspaz

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Cyparagon

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Hiemal

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The Lightning Stalker

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celas

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Aleksa

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celas

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tttonyyy

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Aleksa

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celas

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Aleksa

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celas

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celas

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