Sharp Blu-Ray diode?

[iskor12]

Has anyone tried using a Sharp 405nm 125mW pulsed rated diode? :-?  I have recently been searching for a good 6x diode to use and a vendor that I contacted is trying to push it. I am going to try to get more information about it later.

 

[pseudolobster]

Sounds like a PHR-803T...
125mW pulsed means we won't be able to get much more than 150mW or so out of it.. What's its CW rating?

 

[iskor12]

Sounds like a PHR-803T...
125mW pulsed means we won't be able to get much more than 150mW or so out of it.. What's its CW rating?

I don't know yet. I am trying to get more information out of the vendor. I will likely know buy tomorrow.

I thoght that the phr's pulsed rating was 60mW

 

[Krutz]

i read in some thread here (bluray?) that we push them to twice their pulsed rating? they have quite little heatsinking in their original sleds, and are used much more in there. doesnt matter much if they only have an expected lifetime of 100 hours in a pointer..
i dont think i came across the sharp yet?
so we have four possible successors for the 6x diode?
-sharp
-nichia from o-like
-8x from whole drive
-SF-AW210

manuel

 

[ElektroFreak]

i read in some thread here (bluray?) that we push them to [highlight]twice their pulsed rating[/highlight]? they have quite little heatsinking in their original sleds, and are used much more in there. doesnt matter much if they only have an expected lifetime of 100 hours in a pointer..
i dont think i came across the sharp yet?
so we have four possible successors for the 6x diode?
-sharp
-nichia from o-like
-8x from whole drive
-SF-AW210

manuel

I think that must be a typo, since laser diodes' pulsed ratings are usually much higher than their CW. Take the LPC-815 LDOC diode for example. It's rated to 150mW CW but it's also rated to 400mW Pulsed. I've yet to see anyone get 800mW out of one though..

Here's a link to the datasheet for the open-can: http://www.glyn.de/data/glyn/media/doc/ML101U29.pdf

 

[Krutz]

no typo. i couldnt find the thread again, i am sure it was in the bluray section.. anyway.
it sounds crazy, sure. but then..
-at their pulsed rating, they cant go COD, or they would die, no matter if its pulsed or cw. so its only degeneration and heat that can kill them.
-the sleds are in warm optical drives, which are in warm computers. they have tiny heatsinks, if you want to call them that. so they definitely get warm in there.
-with selling thousands of diodes/sleds/drives, you want them to survive at a good rate. and they should at least survive for the warranty time at a good percentage.

all this summed up:
-they are high-power (relative) by nature, so COD becomes less and less the limiting factor. compare this with IR bars, you can overdrive them like crazy without COD!
-we have them in relatively cool conditions, if its a decent built.
-we dont need thousands of hours, for most of us even a few tens of hours will be more than enough.

with all this, i find "cw at twice their pulsed rating" less and less crazy, but almost plausible..
with phr, 60mw pulsed, 120mw cw, it more-or-less works actually!
its a totally different thing with reds. they seem to COD from one second to the next at the tiniest (final) current increase. if they survive a set current, they seem to survive for quite long..

wishful thinking? who said that! ;-)

manuel

 

[ElektroFreak]

no typo. i couldnt find the thread again, i am sure it was in the bluray section.. anyway.
[highlight]it sounds crazy[/highlight], sure. but then..

It sounds crazy because it IS crazy

-[highlight]at their pulsed rating, they cant go COD[/highlight], or they would die, no matter if its pulsed or cw. so its only degeneration and heat that can kill them.

They definitely can go COD while running pulsed. As easily as CW.. If you looked at the datasheet I gave you, you'd see that the duty cycle for pulsed must be less than 35% and pulse width less than 30ns. 30ns ain't very long. That's why they can be pulsed up to these powers.

-the sleds are in warm optical drives, which are in warm computers. they have tiny heatsinks, if you want to call them that. so they definitely get warm in there.
-with selling thousands of diodes/sleds/drives, you want them to survive at a good rate. and they should at least survive for the warranty time at a good percentage.

all this summed up:
-they are high-power (relative) by nature, [highlight]so COD becomes less and less the limiting factor[/highlight]. compare this with IR bars, [highlight]you can overdrive them like crazy without COD[/highlight]!

Diode bars are just as susceptible to COD as any other diode.

-we have them in relatively cool conditions, if its a decent built.
-we dont need thousands of hours, for most of us even a few tens of hours will be more than enough.

with all this, i find "cw at twice their pulsed rating" less and less crazy, [highlight]but almost plausible.. [/highlight]

except not really

with phr, [highlight]60mw pulsed, 120mw cw[/highlight], it more-or-less works actually!

You mean 120mW Pulsed, 60mW CW. The other way around just doesn't make any sense. The pulsed rating (if there is any) is ALWAYS higher than CW. ALWAYS. With ALL diodes. With ALL lasers for that matter. This isn't opinion, it's the laws of physics.

its a totally different thing with reds. they seem to COD from one second to the next at the tiniest (final) current increase. if they survive a set current, they seem to survive for quite long..

wishful thinking? who said that! ;-)

manuel

mmmm nah not buying any of this... I tell you what, If you can find me one single person who has seen 800mW from their LPC then I'll buy it..

 

[Krutz]

even for a single pulse as short as 30ns, (i believe) it doesnt make any difference for COD. if a diode will COD at 100mw, it will do so no matter if you try to cw it with 100mw or give it a 30ns pulse. in relation to the speed in which the optical power builds up in the cavity, its both really long. with the facets coatings being that thin, its just so little thermal mass that really little energy is needed. once you give it more (optical) energy (converted to heat at the facet) than it can get rid of by heat radiation, it will burn out.
thats what i read at sam's (from memory) and it does make sense to me.
IR diodes: a bar could be rated at 20w, and push out twice of that with still having several thousand hours life.

this all isnt really backed up by hard evidence on my side. there are people here who can prove me wrong with one sentence, if i am ;-)

for phr: i read its rated 60mw. but then we dont have datasheets.. but i am quite sure the "reader" and "4x" and "6x" diodes you find in datasheets arent rated to what we push them, not even pulsed.
do we have *any* br diode with a real datasheet? the nichia one from o-like perhaps?
its driven to 230mw by igor, and rated (on o-like's datasheet) for 120mw max. not even stating if its cw or pulsed, i assume they took the larger number from the original datasheet ;-)

anyway, its not much use to try to discuss with me, i have no prove, but ask for proving me wrong ;-)

manuel

 

[pseudolobster]

No, pulsed rating is always higher. You'll always be able to drive a diode at higher currents so long as you keep it under a few thousands of a second.

For example here's a 16x red's datasheet: http://stonetek.org/shop/SLD1239JL-54.pdf

As you can see the CW rating is only 100mW, yet if it's pulsed it's rated for 180mW. We've been able to run them at 200mW CW but that's shortening its lifespan.

 

[Krutz]

huh? of course i know that in the manufacturer's datasheet the cw rating is substantly lower than the pulsed rating, and would normally be in the range of a half the output! and i am talking about blu-ray only with "we use them in cw at twice their pulsed rating"!

manuel

 

[BlackCandlez]

Pulsed is ALWAYS lower, cause its like this VERY quickly so quick that we can't see it like this in 0.1 secounds On off On off On off On off.

Making it have a higher pulsed cause a CW is On not On off, the On off some how makes it capable of higher pulsed power.

But pulsed sucks for burning.

Also if you move it fast somtimes you can see lots of dots but with CW you will sea line.

 

[jander6442]

pulsed or CW how much is the sharp. Cause if it is $120.00 for 1 piece than it better by at least 80mW of CW.
or we'll not see much fruit from that tree.
Blue Laser Diode FVLD-120S-405
• Absolute Maximum Ratings (Tc=25°C)
Item Symbol Absolute Maximum Ratings Unit
Optical Output Power CW Po 140 mW
LD Reverse Voltage Vr(LD) 5 V
PD Reverse Voltage Vr (PD) 20 V
Storage Temperature Tstg -40 ~ 85 °C
Operating Case Temperature Tc -10 ~ 70 °C
Initial Electrical/Optical Characteristics (Tc=25°C,
Item Symbol Min. Typ. Max. Unit
Optical Output Power Po - - 120 mW
Peak Wavelength lp 400 405 410 nm
Threshold Current Ith - 35 50 mA
Operating Current Iop - 120 150 mA
Slope Efficiency h 1.2 1.4 1.9 W/A
Operating Voltage Vop - 4.8 5.5 V
parallel 7 9 12 deg.
FWHM Beam Divergence
perpendicular 15 19.5 23 deg.
Emission Point Accuracy Position DX,Y,Z - - ±80 [ch956]m
Monitor Current** Im 0.2 0.4 0.7 mA


This is the chart for the sharp I got a quote for. Nice diode but at $250.00 per 1 and quoted for the amount of 100 pieces
=$25,000
You can see where this is going just pony up for the 8x whole burner.
Damn Dave for putting all this in our heads ;D ;D ;D ;D

 

[Krutz]

from sams laser faq:


http://repairfaq.ece.drexel.edu/sam/laserdio.htm#dioldl

I will assume the effect is Catastrophic Optical Damage (COD) of the facet. This is an interaction between the temperature of the facet and its optical absorption. When the temperature of the facet grows, the absorption can also grow which feeds back positively to the temperature and the temperature "runs away" until it is physically damaged. My understanding is that this is extremely fast, certainly less than a microsecond, probably less than a nanosecond. COD is often cited as the mechanism which makes laser diodes extremely ESD sensitive and the ESD discharges can be quite brief.

...

High power diodes (e.g., 1 W) on the other hand are rated near their maximum optical power. How much higher they can be driven is a function of pulse width and duty cycle. To give some typical numbers at a pulse width of 1 ms and duty cycles of a few percent: A diode may be driven at up to 50 percent higher and at pulse width of about 50 ns; at a duty cycle of 0.1% it may driven at up to 5 - 10 times the rated power.

...

We performed experiments with low cost 5 mW, 650 nm CW laser diodes (red laserpointer) with 50 ns, 3 A, 1 kHz, and the LDs worked without pain (no degradation) for months. 100 to 200 ns seems to be the critical pulse length. Also the effective emitting aperture size is important, a 400 mW LD may have a typical 100 um aperture - compared to a red pointer diode of typical 3 to 5 um. The power density mW/aperture size is the most critical value, normally you cannot go much higher than 10MW/cm2 to 30MW/cm2 (Megawatt). Higher power density at the outcoupling facet means sublimation of "mirror" material.
We applied current pulses (fp~10..100 Hz) up to 6 A, typ. 50 ns, but recognized a fast degradation and EELED metamorphosis within few minutes to hours of running.

#######################


so i stand corrected, i think!

well, these quotes just talk about red diodes, nothing about violet diodes. and it still doesnt say much about how the manufacturer "calculates" the ratings.
anyway, i certainly am sure that the phr diodes dont burn out immediately after their rated limits.. ;-)

oh, and sorry for all this threadjacking! *smiles*

manuel