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mophead
05-17-2010, 08:03
Here are a few hi-res shots of the driver, control pcb and head (thanks to kyle for the head pics).

Maybe we can figure out pinouts, serial connections, and which pot is which.

16753167541675516756

Diachi
05-17-2010, 08:15
Head pics aren't showing up for me, anyone else seeing them? :confused:

allthatwhichis
05-17-2010, 08:24
I see em fine. *vigil

mophead
05-17-2010, 08:24
My bad, they didn't attach.

167571675816759

Kyle
05-17-2010, 09:34
Thanks mophead, great shots! I see that you have a newer, version 5.0 board which has two additional pots in comparison with the version 4.0 board.

drlava has confirmed that the pot closest to the laser head DB connector sets the maximum output with the regulation photodiode assembly in place.

I can't swear to it, but I believe the pot I've labeled 3, at least on my version 4.0 board, controls the maximum diode current. For me, turning this pot two revolutions yielded 50% higher output even with the pickoff assembly attached. I made about one-quarter turns each time and a slight increase in power was seen nearly immediately after turning the laser on, although it seemed to take a little bit longer for the green stabilization LED indicator to go off each time. If I remember correctly, the laser head ran noticeably warmer as well.

- Kyle

MechEng3
05-17-2010, 14:47
Just for kicks and grins....

Kyle
05-17-2010, 18:53
Just for kicks and grins....

Thanks for the pic! That many optics to correct the beam of the pump diode, with the crystal set completely encapsulated in the white container? Seems pretty interesting; now I think I have a better understanding of your post in the previous thread.

- Kyle

flecom
05-17-2010, 20:40
anyone tried removing the pickoff assembly or is that a stupid idea? lol *retardo

Kyle
05-17-2010, 21:18
Yes, I've done it several times and it seems to simply ramp the diode current up to some maximum set point. My unit does about 30mW with the pickoff assembly removed.

But it probably isn't such a great idea for the laser's longevity. Although I haven't ran it very long without the pickoff I imagine that it will run warmer and you may risk burning the coatings on the crystals due to the increased output from the pump diode. According to what drlava has said about the maximum current setting on his unit it sounds like these lasers use 2 or 2.5 watt pump diodes. I can't say for certain that the crystals can take this much power.

In short, the laser will operate without the pickoff assembly but it may be risky to do so. :)

- Kyle

flecom
05-18-2010, 18:27
could you turn it back down somewhere? I am sure there is a bit of loss from the pickoff that really isnt nessicary for our purposes anyway?

also I am guessing these things have no kind of modulation inputs right?

Kyle
05-18-2010, 20:05
could you turn it back down somewhere? I am sure there is a bit of loss from the pickoff that really isnt nessicary for our purposes anyway?

also I am guessing these things have no kind of modulation inputs right?

Yep, without going so far as to connect the diode in series with a multimeter, I've nearly confirmed that the pot I labeled 3 on mophead's photo of the driver board controls the diode current, at least on the version 4.0 boards that have three pots total. If I remember correctly, turning pot 3 counterclockwise will decrease the diode current.

If you do this, be sure to mark the original position of the pot if you want to return the laser to its original output later. Also turn the pot in small increments to be sure that I'm correct on the direction of rotation. :)

EDIT: I believe these lasers accept TTL modulation via the thin black and white wires coming from the power supply. The seller twisted them together so that the laser would fire immediately after the 5 second emission delay. I'm not sure what the maximum modulation frequency is, however.

flecom
05-19-2010, 07:35
I will have to try that out... figure could probably run the diode at the same current and get a little extra power, or turn it down to even less current to maintain the current output minus losses...

dont suppose anyone has an idea for decreasing divergence? *retardo

Kyle
05-19-2010, 08:27
While I don't have a wide selection of lenses to choose from a simple double convex lens from a magnifying glass worked somewhat well, IIRC it decreased the divergence from something like 8mRad to under 2mRad, so it's not too great but is still a definite improvement.

If you have a variety of lenses to chose from I'd try out different focal lengths, etc. to see what best collimates the beam. I'm thinking you won't need a complete beam telescope because single lenses seem to work fine as is and beam telescopes would increase the beam diameter about eight times to achieve ~1mRad divergence.

You may get lucky and find a satisfactory lens with a short enough focal length to be mounted inside the laser head, as there is a bit of room available after the crystal set assembly. I'm not an expert on which epoxy or glue to use but you'll need something that doesn't outgas and has a low degree of shrinkage/expansion.

- Kyle

MarioMaster
05-19-2010, 11:02
Looks to me like the output beam is straight from the crystals. I made a very nice beam with my units by making a simple beam expander from a short focal length lens and a longer focal length lens - you'll probably need to experiment with the focal lengths as these are just lenses I had laying around.

I was lucky to get three of these units from the seller before they were all gone. With the pickup assembly they do about 10mW, on the one I removed it runs about 30mW. All have nice round spots although some have some spatter (I was told that this may just be from a dirty IR filter on the front of the unit but I have not tried to clean it yet)

allthatwhichis
05-19-2010, 11:03
Looks to me like the output beam is straight from the crystals. I made a very nice beam with my units by making a simple beam expander from a short focal length lens and a longer focal length lens - you'll probably need to experiment with the focal lengths as these are just lenses I had laying around.

I was lucky to get three of these units from the seller before they were all gone. With the pickup assembly they do about 10mW, on the one I removed it runs about 30mW. All have nice round spots although some have some spatter (I was told that this may just be from a dirty IR filter on the front of the unit but I have not tried to clean it yet)

Moar pics... *retardo

hologeek
05-19-2010, 11:10
'I was told that this may just be from a dirty IR filter on the front of the unit but I have not tried to clean it yet'

I've noticed that too on some of the units I have. On these, the cavity window/IR filter is scratched. I almost wonder if this was done on purpose, prior to them being sold to the surplus reseller...

Kyle
05-19-2010, 12:08
Looks to me like the output beam is straight from the crystals. I made a very nice beam with my units by making a simple beam expander from a short focal length lens and a longer focal length lens - you'll probably need to experiment with the focal lengths as these are just lenses I had laying around.

I was lucky to get three of these units from the seller before they were all gone. With the pickup assembly they do about 10mW, on the one I removed it runs about 30mW. All have nice round spots although some have some spatter (I was told that this may just be from a dirty IR filter on the front of the unit but I have not tried to clean it yet)

Yes, the output beam is coming straight from the crystals, as these lasers were designed to go straight to a fiber coupler a collimation assembly wasn't needed. I think I measured my unit to have about 8mRad raw divergence and was worried that I couldn't get the first lens of a beam expander close enough to the crystal to get a small one or two millimeter initial diameter out of the expander. I'll have to see if I can find some lenses with the right focal lengths so that I could place the first lens within the laser head itself and have the second lens on the outside.

Mine has some spatter around the raw beam and upon closer inspection it appears that the beam from the crystal is hitting the side of the crystal enclosure ever so slightly, causing a line to appear next to the main ovular beam.

krazer
05-22-2010, 13:44
aI am sorry I haven't been able to add much to this thread due to general lack of time, but I have got the serial ports working, it has 2 serial ports, which I am going to call 1 and 2. They are available from J10, and are RS232 compliant (can safely be connected directly to a computer). I haven't been able to figure a whole lot out, but it appears that one of them is associated with the automatic temperature tuning, and the other one lets you 'talk' to the laser.

Port 1: (general laser control)
9600 baud, 8 data bits, no parity, 1 stop bit
TX - pin 7/8 (connect to pin 2 on a normal db9 serial port)
RX - pin 9/10 (connect to pin 3 on a normal DB9 serial port)
Gnd - pin 5/6 (connect to pin 5 of a normal DB9)

Commands (all commands are followed with a new line, all appear to be case sensitive)
b - ??? - mine just echoes back a B, occasionally sending back a BX
e - setpoint? - mine responds E00829 - which matches with the setpoint read out from serial port 2, and does not change when the photodiode is blocked
s - status? mine responds S00000 with the pd in place, or S00003 with it removed or before the laser has powered up
v - version? - mine responds V45040
w - warming up? - mine responds with W00001 after I first plug it in, and W000000 after a few minutes


Port 2 - doubler temperature tune output
115200 baud, 8 data bits, no parity, 1 stop bit
TX - pin 3/4 (connect to pin 2 of a normal DB9)
RX - pin 1/2 (connect to pin 3 of a normal DB9)
gnd - pin 4/5 (connect to pin 5 of a normal DB9)

When I first power it up I get:


Save[5]=1525 Save[6]=1 Tcon_ld=1526

1895 0 1490 65503 1525 1
KTP temperature has been tuned 0 times!

Beginning temperature point tuning!
From 1892 to 1898, step 3.

Tcon=1859

And after a minute or so it will start scanning the doubler (it calls it KTP, I assume that is left over from driving a 532nm laser), giving a few thousand lines of:


Save[5]=1525 Save[6]=1 Tcon_ld=1526

1895 0 1490 65503 1525 1
KTP temperature has been tuned 0 times!

Beginning temperature point tuning!
From 1892 to 1898, step 3.

Tcon=1859
k=1 m=0 Tcon=1859 Trt=1886
k=2 m=0 Tcon=1865 Trt=1887
k=3 m=0 Tcon=1865 Trt=1887
k=4 m=0 Tcon=1865 Trt=1886
k=5 m=0 Tcon=1865 Trt=1887
k=6 m=0 Tcon=1865 Trt=1887
k=7 m=0 Tcon=1865 Trt=1887
[few hundred lines]
k=999 m=1 Tcon=1864 Trt=1893
k=1000 m=1 Tcon=1864 Trt=1893
k=1001 m=1 Tcon=1864 Trt=1893
k=1002 m=1 Tcon=1864 Trt=1893
k=1003 m=1 Tcon=1864 Trt=1893
got it!
k=1004 m=2 Tcon=1864 Trt=1893
got it!
k=1005 m=3 Tcon=1864 Trt=1893
got it!
k=1006 m=4 Tcon=1864 Trt=1892
got it!
k=1007 m=5 Tcon=1864 Trt=1893
got it!
k=1008 m=6 Tcon=1864 Trt=1892
got it!
[few hundred lines]
k=1499 m=497 Tcon=1864 Trt=1893
got it!
k=1500 m=498 Tcon=1864 Trt=1892
got it!
k=1501 m=499 Tcon=1864 Trt=1893
got it!

Pd=830

Pd is higher than 800!

Id=217

Id is below 330!

Id is below 300!

judge2=0 down2=1 all_down2=1

judge1=0 down1=1 all_down1=1

judge=0 down=1 all_down=1

[then it starts to repeat itself]

Tcon=1866
k=1 m=0 Tcon=1866 Trt=1895
got it!
k=2 m=1 Tcon=1866 Trt=1895
....



And with the photo diode removed off the front, I get:


Tcon=1859
k=1 m=0 Tcon=1859 Trt=1885
k=2 m=0 Tcon=1866 Trt=1885
k=3 m=0 Tcon=1866 Trt=1885
k=4 m=0 Tcon=1866 Trt=1885
k=5 m=0 Tcon=1866 Trt=1884
k=6 m=0 Tcon=1866 Trt=1885
k=7 m=0 Tcon=1866 Trt=1885
k=8 m=0 Tcon=1866 Trt=1885
k=9 m=0 Tcon=1866 Trt=1885
k=10 m=0 Tcon=1866 Trt=1885
k=11 m=0 Tcon=1866 Trt=1884
k=12 m=0 Tcon=1866 Trt=1885
k=13 m=0 Tcon=1866 Trt=1885
k=14 m=0 Tcon=1866 Trt=1885
k=15 m=0 Tcon=1866 Trt=1885
k=16 m=0 Tcon=1866 Trt=1885
k=17 m=0 Tcon=1866 Trt=1885
k=18 m=0 Tcon=1866 Trt=1884
k=19 m=0 Tcon=1866 Trt=1885
k=501 m=0 Tcon=1866 Trt=1893
[few hundred lines]
k=502 m=0 Tcon=1866 Trt=1893
got it!
k=503 m=1 Tcon=1866 Trt=1893
got it!
k=504 m=2 Tcon=1866 Trt=1892
got it!
k=505 m=3 Tcon=1866 Trt=1893
got it!
k=506 m=4 Tcon=1866 Trt=1893
got it!
k=507 m=5 Tcon=1866 Trt=1893
got it!
[few hundred lines]
k=1000 m=498 Tcon=1866 Trt=1893
got it!
k=1001 m=499 Tcon=1866 Trt=1892
got it!

Pd=37
No Pd detected! Pd=37

Id=329

Power's too low!

judge2=0 down2=1 all_down2=1

judge1=1 down1=0 all_down1=0

judge=1 down=0 all_down=0

Tcon=1869


I am not sure what the numbers at the beginning mean, but Pd=xxx appears to be what the photodiode is reading, and Id appears to be the diode current. Its possible that Id reads in 10ma increments (ie Id=217 = 2.17A), but I have not been able to comfirm


One last comment to anyone looking to build a nicer box for the laser, the supply needs to be heatsunk with a fairly decent heatsink, and it does not appear to have any form of overheat protection integrated into it. The laser head seems to be fine without any additional heatsink, but the power supply definitely will overheat without some help.

Kyle
05-22-2010, 14:13
Thanks for the pinouts and info, krazer! Really good work. I take it that you haven't been able to override the automatic temperature tuning and manually tune the temperature of the crystal set for higher output, no?

And you're saying that the included heatsink is not sufficient? I've ran my unit for several hours at a time and the heatsink has never gotten extremely hot. I'll look around for a beefier heatsink to attack the driver to.

- Kyle

krazer
05-22-2010, 14:43
The piece of metal it is mounted on seems to work fine, but in testing with that plate removed the supply quickly warmed up to dangerous levels.

I haven't managed to get the laser to respond to anything on serial port 2, randomly mashing the keyboard seemed to have no response.

A few comments I forgot to add in the previous post-
1. serial port 1 - 9600 baud 8 bits no parity 1 stop bit
2. serial port 2 - 115200 baud 8 bits no parity 1 stop bit
3. the laser definitely has a light control loop, interrupting the beam before the photo diode sensor causes the current to very quickly ramp up to a maximum level. I lent my scope out so I can't see how quickly, but there might be hope to modulate this thing at a reasonable rate. You can see how much the current increases by looking at the printout in my previous post, with the pickoff in place it was running at 217 arbitrary units (I am guessing that means 2.17A?) and with it removed the current jumped up to 329 units (3.29A?). Has anyone been able to read the resistance of R53 (mounted on the heatsink between Q4 and Q6)? I am assuming it is the current sense for the diode, I measured 1.24v for 217 units of diode current as read out by the doubler tuning algorithm.
4. The warranty sticker on the back doesn't actually do anything, by removing the 6 screws on the bottom you can lift the whole inside of the laser out (although you can't do a whole lot due to the short length of the wires). I just thought I should mention it, just because the sticker is still there the head could be completely stripped for all you know.
5. Looking at the board, it appears that pots 5 and 4 appear to have been disabled (note how r54 and r55 labeled 0ohms have been removed), so I am assuming at least the settings those pots originally set are being set by the daughterboard on top.

Kyle
05-22-2010, 15:34
Thanks again krazer, once again a very informative post! You have done much more fiddling with these lasers than I have and I appreciate the extra information you've provided.

drlava said that his unit had a maximum diode current setting at around 1.95A, so your unit running at a max of 3.29A seems a bit high.

I have a version 4.0 driver board and it appears that R53 is absent. It is marked on a trace and there are two solder pads below this trace but there is no component present. For the record, I'm nearly electronically retarded so I may be overlooking something.

I was thinking about removing the base from the lid via the bottom screws but have not done so yet; it's nice to know that is somewhat possible.

I'm also relieved to here that pots 4 and 5 are nonfunctional, as the version 4.0 boards don't have them. That's one less thing to worry about as I try to squeeze a bit more power out of my unit.

- Kyle

krazer
05-22-2010, 16:33
R53 is a big transistor looking thing, soldered in from below like Q4 and Q6, and is bolted to the baseplate, between said Q4 and Q6. I got up the courage to take my driver apart, and have confirmed it to be a 1ohm resistor on my board, showing that in normal operation the diode is running at 1.24A, and 1.94A with the pickup removed. A quick comparison to my reported values and everything looks linear, with the output in the form of Iout [mA] = Id*5.8. If anyone else wants to 'calibrate' yours, just take the reading with the photo diode removed, take 2000 divided by the reading, and you should be fairly close (within 5%).

Kyle
05-22-2010, 19:01
Ah, okay, thank you! I saw the TO-220 package and thought that it was a transistor or IC of some sort. Maybe one day I'll get around to connecting the driver to a PC and toy around a bit. It's good to know that we can check the diode current quite easily now, that probably would have helped when I was trying to figure out which pot controlled that setting. :p

- Kyle

danielbriggs
06-24-2010, 02:38
Krazer,
Thanks for the info on the driver :)

This unit does 8mW with PD. 16mW without PD.

I know it's very similar, but here is the output of mine:

WITH Photodiode:


Save[5]=1400 Save[6]=65498 Tcon_ld=1362

1795 0 1380 8 1400 65498
KTP temperature has been tuned 0 times!

Beginning temperature point tuning!
From 1792 to 1798, step 3.

Tcon=1800
k=1 m=0 Tcon=1800 Trt=1790
k=2 m=1 Tcon=1801 Trt=1791
k=3 m=1 Tcon=1801 Trt=1790
k=4 m=1 Tcon=1801 Trt=1791
k=5 m=1 Tcon=1801 Trt=1791
...lots of lines...
k=500 m=1 Tcon=1801 Trt=1793
k=501 m=1 Tcon=1801 Trt=1792
k=502 m=1 Tcon=1801 Trt=1792
got it!
k=503 m=2 Tcon=1801 Trt=1792
got it!
k=504 m=3 Tcon=1801 Trt=1792
got it!
k=505 m=4 Tcon=1801 Trt=1792
got it!
...lots of lines...
k=998 m=497 Tcon=1801 Trt=1792
got it!
k=999 m=498 Tcon=1801 Trt=1792
got it!
k=1000 m=499 Tcon=1801 Trt=1792
got it!

Pd=827

Pd is higher than 800!

Id=186

Id is below 330!

Id is below 300!

judge2=0 down2=1 all_down2=1

judge1=0 down1=1 all_down1=1

judge=0 down=1 all_down=1

Tcon=1804
k=1 m=0 Tcon=1804 Trt=1795
got it!
k=2 m=1 Tcon=1804 Trt=1795
got it!
...repeats...



WITHOUT Photodiode:


Save[5]=1400 Save[6]=65498 Tcon_ld=1362

1795 0 1380 8 1400 65498
KTP temperature has been tuned 0 times!

Beginning temperature point tuning!
From 1792 to 1798, step 3.

Tcon=1800
k=1 m=0 Tcon=1800 Trt=1789
k=2 m=0 Tcon=1803 Trt=1789
k=3 m=0 Tcon=1803 Trt=1788
k=4 m=0 Tcon=1803 Trt=1789
k=5 m=0 Tcon=1803 Trt=1788
...lots of lines...
k=500 m=0 Tcon=1803 Trt=1792
k=501 m=0 Tcon=1803 Trt=1792
k=502 m=0 Tcon=1803 Trt=1792
got it!
k=503 m=1 Tcon=1803 Trt=1792
got it!
k=504 m=2 Tcon=1803 Trt=1792
got it!
k=505 m=3 Tcon=1803 Trt=1792
got it!
...lots of lines...
k=996 m=494 Tcon=1803 Trt=1792
got it!
k=997 m=495 Tcon=1803 Trt=1792
got it!
k=998 m=496 Tcon=1803 Trt=1792
got it!
k=999 m=497 Tcon=1803 Trt=1792
got it!
k=1000 m=498 Tcon=1803 Trt=1792
got it!
k=1001 m=499 Tcon=1803 Trt=1792
got it!

Pd=38
No Pd detected! Pd=38

Id=346

Power's too low!

judge2=0 down2=1 all_down2=1

judge1=1 down1=0 all_down1=0

judge=1 down=0 all_down=0

Tcon=1806
k=1 m=0 Tcon=1806 Trt=1795
got it!
k=2 m=1 Tcon=1806 Trt=1795
got it!
k=3 m=2 Tcon=1806 Trt=1795
got it!
...repeats...

Xplorer877
07-21-2010, 08:12
Hey guys, new here, but not to the hobby.

Thanks for all the information posted! I just picked one of these up and am really excited. Has anyone figured out a good setup for the beam correction optics? Any pics of your set ups?

It looks like I've got the old version of the board too.
http://i551.photobucket.com/albums/ii450/Xplorer822/DSC09249.jpg
http://i551.photobucket.com/albums/ii450/Xplorer822/DSC09242.jpg

-Tony