Is my blue labby DOA?

docjohn · Oct 6, 2008

I bought a used 300mw blue laser that was removed from a RGBLP1000 RGB projector (made in Hungary). The blue laser head and the driver board were removed from the projector and sold on e-bay. The owner wanted to increase his blue power with another blue. The driver board requires an input of 12v, 5v, and a 0-5v. analog input for modulation. They were connected by an umbilical cord. When all voltages were connected, It did not lase.

[highlight]Observations[/highlight]

The 12v drew 1.5 A. and was labeled TEC. The 5v. drew 4.5 A. The mod input drew 1ma no matter where it was set (0 to 5v.)

The heat sink of the driver and the heat sink of the laser head got warm as expected.

Nothing was registered on a LPM in front of the laser (no IR)

No current changed anywhere by varying the mod input voltage.

The voltage reading on the board where the 5v. 4.5A connected read 3.2v and did not change by changing the 5v input. (just like a zener diode)

[highlight] Questions[/highlight]

Do the currents sound right?

Is the 3.2v 4.5A going to the laser head probably driving the IR diodes?

How could I determine if the IR diodes are good or DOA?

Picture of it

Docjohn

FokoF · Oct 6, 2008

Photonlexicon might be a better place to ask...... :-?

diachi · Oct 6, 2008

It sounds like the blanking might not be working, it usually draws more than 1mA at 5V .

-Adam

EDIT : as said above www.photonlexicon.com would be a better place to ask ,

docjohn · Oct 6, 2008

thanks will post there also

diachi · Oct 6, 2008

Your welcome !

docjohn · Oct 6, 2008

Diachi said:
It sounds like the blanking might not be working, it usually draws more than 1mA at 5V .

-Adam

EDIT : as said above www.photonlexicon.com would be a better place to ask ,

Adam, how much current would you expect the blanking input to draw?

John

laserfreak3d · Oct 7, 2008

4.5 amps sounds about right for a ir diode
300 mw of blue should need about 3-4 wats of ir power
the tecs current also sounds right at 1.5

but.

Normaly with no blanking input active the diode should be in idle.
So normaly thats just bellow threshold power of the diode.
So if its already drawing 4.5 amp with no input on the analog input there's something wrong.
Could be that the driver is faulty.
If its stil drawing 4.5 amps when u disconnect the head from the driver (if possible) (use esd precautings if possible )
the driver is faulty.
Could also be that the analog blanking input is faulty but at 4.5 amp current draw the diode should have full output.
It could also be that the diode is defective or whas damaged by esd.
In that case it could stil draw 4.5 amps with just a couple of hundred mw's of ir output and thats not enought to excite the crystals in the head.
Most likely the output window has a good quality ir filter so normaly u should not be able to measure any output or just a slight amount
best way to make sure the diode is stil lasing is to open the head pwr up the laser and check for ir output with a camera or power meter.
Also make sure u dont take any risk with your eye 4 watts of ir is a lot of power even when reflected from a surface and not focused

If all of this fails
I can always take a look for u.
I have been repairding dpss and diode lasers for several years now

Cyparagon · Oct 7, 2008

Yes, I'd suggest disconnecting the head to determine if it draws the same power. I suspect it's dead.

Even if the value decreases, it could be the TEC that causes it. (Does this head have TEC? I would hope so)

laserfreak3d said:
300 mw of blue should need about 3-4 wats of ir power

Blues operate at 1-3% pump efficiency, not 7.5-10%. 300mW of blue requires anywhere from 10-30 watts pump power depending on crystals.

thesk8nmidget · Oct 7, 2008

yes this laser is tec cooled! thats pretty mandatory with dpss blue

docjohn · Oct 7, 2008

laserfreak3d said:
4.5 amps sounds about right for a ir diode
300 mw of blue should need about 3-4 wats of ir power
the tecs current also sounds right at 1.5

but.

Normaly with no blanking input active the diode should be in idle.
So normaly thats just bellow threshold power of the diode.
So if its already drawing 4.5 amp with no input on the analog input there's something wrong.
Could be that the driver is faulty.
If its stil drawing 4.5 amps when u disconnect the head from the driver (if possible) (use esd precautings if possible )
the driver is faulty.
Could also be that the analog blanking input is faulty but at 4.5 amp current draw the diode should have full output.
It could also be that the diode is defective or whas damaged by esd.
In that case it could stil draw 4.5 amps with just a couple of hundred mw's of ir output and thats not enought to excite the crystals in the head.
Most likely the output window has a good quality ir filter so normaly u should not be able to measure any output or just a slight amount
best way to make sure the diode is stil lasing is to open the head pwr up the laser and check for ir output with a camera or power meter.
Also make sure u dont take any risk with your eye 4 watts of ir is a lot of power even when reflected from a surface and not focused

If all of this fails
I can always take a look for u.
I have been repairding dpss and diode lasers for several years now

I will check it tonight with the top off and my goggles on.

Thanks, John

docjohn · Oct 9, 2008

[highlight]I also poster this at LP but I think the more heads the better. We all have something to contribute
[/highlight]
Last night I took the lid off the head. I applied all voltages. I saw a faint red glow where the 808 diode is. It was a much brighter white thru my CCD camera. There was no change in intensity of the red with changing the mod voltage from 0 to 5v. Also the current going to the diode remained at 4.5 amps. Very faint blue-purple dot seen by CCD camera when looking into the output of the laser head. My conclusion is that the 808 is putting out very little 808nm. 10 watts of 808nm should be more than a faint red glow with the top off. Its seems that the crystals are ok.

Tonight I will check the current going to the diode as measured after the driver. So far I have only measured the current that the 5v bench supply is supplying to the PCB driver input.

Thanks,John

MarioMaster · Oct 9, 2008

sounds like the diode may just be sitting at the idle current - or the diode is damaged

sucks to have problems with such a nice laser

GooeyGus · Oct 11, 2008

Well even if the diode is totally toasted (which I really doubt! Usually these diode are ran at a power level LOWER than their rated power), the good news is a diode isn't too expencive and relatively easy to change, but I still suspect that there is something else causing your problem

thesk8nmidget · Oct 11, 2008

yeah i think we have come to the conclusion that the driver is what needs to be sorted out.

ie the power supply/s

and getting the right kind of power to the driver to get it to lase

docjohn · Oct 12, 2008

[highlight] author=thesk8nmidget .yeah i think we have come to the conclusion that the driver is what needs to be sorted out.

ie the power supply/s

and getting the right kind of power to the driver to get it to lase[/highlight]

That would be great Josh. I am on LP now with this thread. Many thanks guys for your input !!!

http://photonlexicon.com/forums/showthread.php?t=5488

John

Is my blue labby DOA?

docjohn

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