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FrozenGate by Avery

Mitsubishi-G84-638nm-2500mW-Laser-Diode

styropyro said:
My diode is behaving very oddly...don't know if this is a sign of imminent death or not as I have never seen this before...

I was running the diode at 2.5A (direct from my PSU, shorted before applying power) for something like a minute and it dimmed out to nearly no output over a period of a few seconds. But, when I give it juice again, it runs at apparently full power for about 10 or 15 seconds before dimming out again. The voltage of my PSU is set well above the forward voltage of the diode so that isn't the problem.

I don't have my LPM on hand so I can't tell if there has been a change in output power, but the raw output has nothing odd in it compared to when I first powered it up.

Weird.
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See bens post right above yours...Logsquared has a valid point, but the p73's are also meant for pulsed operation ;) I think static discharge from the plastic bag it was packaged in is to blame.
 





The graph on the datasheet struck me as strange when I first looked at it. They are actually rating it for higher current at higher amperage. Usually it the other way around. My guess is they want to keep the optical power below 2.5W and the diode gets very inefficient at higher temps.

The P73 is rated at 1W 33% IIRC? Pretty close to this new diode if you account for double emitters.

The fact that this diode emits 3 beams is really strange. Very curious... Is it a different diode all together with 3 emitters? Or is it damaged by poor packing? Very sad if its damaged by a cheap bag!
 
Yeah it's a miracle that this diode even lased at all considering what it has been through. It likely suffered at least some damage along the way though...I'll have to experiment with cooling the diode to see what happens.
 
styropyro said:
Yeah my setup is definitely far from optimum, and the operation is definitely not pulsed, but I've just never seen a laser diode behave like this before. Usually when a LD dims out it is either dead, or for the case of the indestructible blue LDs, at too high of current.

Edit: Oh, and my laser diode spits out three beams, not two!
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Thats what ive been hearing! Cant wait to see what you do with it
 
styropyro said:
Just posted a video of this laser diode! I didn't address the weird behavior of my diode, but at least gave a quick overview of the output. Enjoy!


https://www.youtube.com/watch?v=clGhGacfiqI&feature=youtu.be
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I would comment but the second you upload it already has 500 views lol, cant wait to see it in that pointer. Can you power it with 2x16340s? Also to answer your question at the end, its apparently for a scanner (exactly thats rediculously high for a scanner), but i cant get o like to tell me what scanner exactly
 
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No doubt that is a new diode with three emitters. With the correct mag cylinder beam expander you should be able to make the beams parallel. Unfortunately no optics can overlap the individual beams.
 
This certainly is one of the oddest laser diodes to ever hit the market.

I see it is supposed to have 2 beams but apparently can have 3 as well, which would sort of rule out two cavities running side by side as the cause for this strange beam pattern.

As for its intended application i'm really curious. It could be for a barcode scanner of some kind, just sweeping all the beams over the barcode. At very high throughput speed it would make sense to use very intense light for that, though i don't really see the point of 638 vs 660 nm light at all.

Also, having 2 beams is not an advantage in that application (though not a problem either). I doubt this randomly runned off the production line producing two beams, so perhaps it's intended purpose was something very different. I can imagine some spectrophotometic setup where one beam passes through a sample and the other is the reference, though that would require the intensities of both beams to be very well matched (no idea if that is the case?).
 
Benm said:
This certainly is one of the oddest laser diodes to ever hit the market.

I see it is supposed to have 2 beams but apparently can have 3 as well, which would sort of rule out two cavities running side by side as the cause for this strange beam pattern.

As for its intended application i'm really curious. It could be for a barcode scanner of some kind, just sweeping all the beams over the barcode. At very high throughput speed it would make sense to use very intense light for that, though i don't really see the point of 638 vs 660 nm light at all.

Also, having 2 beams is not an advantage in that application (though not a problem either). I doubt this randomly runned off the production line producing two beams, so perhaps it's intended purpose was something very different. I can imagine some spectrophotometic setup where one beam passes through a sample and the other is the reference, though that would require the intensities of both beams to be very well matched (no idea if that is the case?).
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Also some have 3 beams, styro can you do a closeup of the diode window for us? Ill post a macro in a few days
 
logsquared said:
The graph on the datasheet struck me as strange when I first looked at it. They are actually rating it for higher current at higher amperage. Usually it the other way around. My guess is they want to keep the optical power below 2.5W and the diode gets very inefficient at higher temps.

The P73 is rated at 1W 33% IIRC? Pretty close to this new diode if you account for double emitters.

The fact that this diode emits 3 beams is really strange. Very curious... Is it a different diode all together with 3 emitters? Or is it damaged by poor packing? Very sad if its damaged by a cheap bag!
Click to expand...

The 3 emitter model is a separate diode. Apparently it isn't in production yet, so idk if they are just samples or what.
 
crazyspaz said:
The 3 emitter model is a separate diode. Apparently it isn't in production yet, so idk if they are just samples or what.
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I have heard a few people say they got the three beam emitter not the two beam one.
 
Update: You can find this diode tin pin at 39 dollars each on ebay now, 55 for brand new/no solder on the pins.

www.ebay.com

ML562G84 φ9mm Red 638nm 635nm 2W+ 2.5W Laser Diode (Tin-Pin) High Power | eBay

Find many great new & used options and get the best deals for ML562G84 φ9mm Red 638nm 635nm 2W+ 2.5W Laser Diode (Tin-Pin) High Power at the best online prices at eBay! Free shipping for many products!
www.ebay.com

If this diode is kept to 25 C or lower temperature, the diode can output a total of over 5.5 watts pulsed power at a 30 percent duty cycle 120 Hz.




---------------------------------------------------

See this, the article mentions running the diode over 7 watts total output when using short pulse width and duty cycle (the total power split into three beams) in its test without a failure and estimating thousands of hours of MTTF at that power if the temperature is kept low enough.

The P-I characteristics of ML562G84 under Tc of -18 °C, pulse width of 6 msec, Dc of 10% is shown in Fig. 8. In the figure, not only the curve just after burn-in (initial) but also that after 2400 hours aging are shown.

The aging condition was initial output of 2.5W, ACC, CW, and Tc of 45°C. The curve at initial showed no degradation up to 10W, on the other hand the LD after 2400 hours aging degraded at power of 7.7 W, indicating PCOMD may decrease in the aging.

Note Fig. 7 PCOMD dependence on pulse width and duty cycle 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 0.1 1 10 100 PCOMD [W] Pulse width [ms] Duty 10% Tc: 0℃. The results mean that the PCOMD under the pulse operation with pulse width longer than 6 msec may be the same as that under the CW condition.
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The over-drive aging test method to estimate MTTF is a sure and powerful method in case that the LD under testing can output enough power for acceleration, because MTTF(COMD) is strongly affected by Pd. And it is desirable for the aging to be performed under CW, not pulse, because CW aging makes total on-time duration longer compared with pulse condition in the same duration. ML562G84, triple emitter BA-LD, is designed only for high power operation under pulse condition with Dc around 30% as mentioned in section 2, resulting not so excellent P-I characteristics under CW, especially highly input current and high temperature. Thus the new methodology to estimate MTTF(COMD) is required.
Click to expand...
 
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Alaskan said:
Update: You can find this diode tin pin at 39 dollars each on ebay now, 55 for brand new/no solder on the pins.

www.ebay.com

ML562G84 φ9mm Red 638nm 635nm 2W+ 2.5W Laser Diode (Tin-Pin) High Power | eBay

Find many great new & used options and get the best deals for ML562G84 φ9mm Red 638nm 635nm 2W+ 2.5W Laser Diode (Tin-Pin) High Power at the best online prices at eBay! Free shipping for many products!
www.ebay.com

If this diode is kept to 25 C or lower temperature, the diode can output a total of over 5.5 watts pulsed power at a 30 percent duty cycle 120 Hz.




---------------------------------------------------

See this, the article mentions running the diode over 7 watts total output when using short pulse width and duty cycle (the total power split into three beams) in its test without a failure and estimating thousands of hours of MTTF at that power if the temperature is kept low enough.



Click to expand...
I'm curious how pulsed operation relates to perceived brightness. Does running a diode pulsed at 4 watts, 50% duty cycle appear to be brighter than the same diode running 2 watts CW? It would make sense to me that lower repetition rates for a given duty cycle would appear brighter than high repetition rates, I would guess as the repetition rate increases the more the overall brightness would appear "averaged" to match the duty cycle multiplied by the output, with longer repetition appearing brighter but having the unpowered segment of the cycle more noticeable.. but that's just a guess.
 
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Well, I hope so, ordered some of those diodes and already have the PWM module and driver which will accept pulse width modulation Redcowboy recommended. I've seen pulse modulated DPSS lasers look much brighter with higher peak power when pulsed, I'm hopeful these diodes will look brighter too.

Anyone here with experience pulsing visible wavelength diodes? I don't know why a manufacturer would make a 639 nm red diode at this power output to be pulsed unless it does make a big difference. Regardless, if you can keep the diode cooled to 25C with a TEC, the article I read shows they can produce over 5 watts output CW and last for thousands of hours, good enough for me!

According to the article, the reason this particular diode can produce double the rated output and still last that long is due to the three beams, since the power is split between three beams, the emitter output mirrors for each do not degrade very quickly when the output is doubled beyond design as it would with a single emitter diode being pushed that much over the design power, due to lower power density into the mirror. For example, each emitter this diode has is 60 um wide for a total of 180 um, the single emitter 2 watt 638 nm pulse LD this company produces has only a 40 um diameter emitter, so even at 2 watts there is far more power density into the output mirror deposited upon the LD emitter substrate. The study tried to see how well that diode would perform being pushed hard too, it died a toasted death very quickly from damage to its integral mirror. Compared to Mit's 2.1 watt single emitter 638 nm pulse diode, there is one more plus for this 3 beam diode, due to its wider emitters, they each have lower thermal resistance to the mounting structure inside the 9 mm housing, so don't get as hot for a given amount of input power to each of them.

Only thing is, this diode produces 3 beams, but I find that novel, like it. Something to be aware of, prior to collimation the output is like 70 degrees wide on one side and very thin on the other polarity. Due to this, unless using a short focal length lens, a 6.33 mm diameter lens like we commonly use in our pointers may not do well with it and truncate or cut off *some of the output power. So, unless using a very short FL 6.3 mm diameter lens such as a G2 (with about a 2 mm focal length) too much power might be lost, but I'm not even sure of that, maybe it will block far too much of the diode output.

If the G2 will allow all three beams to escape the small lens holder barrel, it would be moot to me anyway, still a poor choice of collimation lens because with such a short FL lens the divergence is going to be hell, horrible, crappy, shitty beyond comparison.... so my thought for pointer use is to use a 25.4 mm/1 inch diameter lens or larger with this diode.

Another issue for pointers though is the wide stripe each of the three beams will produce in the distance, quickly loosing visual power before the beam gets very far away, not to mention red wavelengths are so much less brilliant to our eyes at any power level, you still have that drawback. Beam shaping can help with the thin beam shape, but if you want to change the beam shape from a thin rectangle to more of a square shape, where can we get some cylinder pairs good for 9 to 10X expansion of the thin side which are fairly wide for all three beams? I guess we would have to use a prism pair, or more, those can be added to, just add more of them but at the cost of power from added loss.
 
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If you had 2 PBS cubes you could combine all 3 beams in to one by using bounce mirrors to make two 90 degree intersections, one after the other, and each of the two beams to be combined would need their own wave rotator.. but still would be neat to have a single, overlapped 5 watt beam. I think there was a dual beam USHIO 3 watt (may have even been 3.5 watts) unit that would be less work and money to combine the beams but I don't know if it has the durability of the Mits unit here to be overdriven and cooled to be able to achieve 5 watts from the one diode.
 
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