27000 Hours

[AngelG]

Interesing. Too bad that there were no 405 nm diodes back then to compare.
I have tied 3 white LEDs on my door and 2 of them lasted ~ 2 years, then died. The third is still running for 4th year. The current I run them is within the proposed by the manufacturer, no heat generated since they're low power.
Nowadays there are $1 20mW 405nm LDs which could be put to test I've heard that UV causes the green plants to grow faster, probably it's suitable for а greenhouse.

 

[edslittleworld]

Sorry for perpetuating an OLD thread, but how much of that limited lifespan could have been attributed simply to natural degradation of the diode which occurs even in an unpowered state?

For instance, I have a 2014 Class 4 DPSS 532nm laser that has MAYBE 20 minutes of operating time. Even with a low MTBF rating of 5000 hours...the laser diode would theoretically last over 10,000 years if you consider operating time to be the sole determinate of diode life. Plus, there are other limited-life components of a DPSS laser like the KTP crystal, etc.

 

[ultimatekaiser]

This post makes no sense...? and no diode's don't go bad sitting around generally speaking.

The laser was run continually-all the time 24/7 as far as I know. Most laser diodes if run at rating and at between 20-25C usually last 5,000-10,000 hours, but I've seen plenty last longer, even approaching 20K+ in some instances. depends on a lot of factors, and some luck. We had an LWE and an Adlas last us since the mid 90s until recently down here with about 10K on one, and about 18K on the other. This was probably a higher power diode being somewhat underdriven.

Also, crystals in lasers don't degrade over time if they're in a sealed environment unless you push them beyond their damage threshold or the user scratches them or something.

Although, some will degrade from moisture, but that's an easy thing to solve, using dessicant and sealing the laser head, which most professionals do anyway when it is needed, or they will flush the head with dry inert gas or both.

 

[edslittleworld]

This post makes no sense...? and no diode's don't go bad sitting around generally speaking.

The laser was run continually-all the time 24/7 as far as I know. Most laser diodes if run at rating and at between 20-25C usually last 5,000-10,000 hours, but I've seen plenty last longer, even approaching 20K+ in some instances. depends on a lot of factors, and some luck. We had an LWE and an Adlas last us since the mid 90s until recently down here with about 10K on one, and about 18K on the other. This was probably a higher power diode being somewhat underdriven.

Also, crystals in lasers don't degrade over time if they're in a sealed environment unless you push them beyond their damage threshold or the user scratches them or something.

Although, some will degrade from moisture, but that's an easy thing to solve, using dessicant and sealing the laser head, which most professionals do anyway when it is needed, or they will flush the head with dry inert gas or both.

So...you're telling me that if I store my quality laser and use it only a few times a year, it should theoretically last forever? I understand that ALL electronics degrade over time...especially the dielectric components like capacitors. However, you apparently own enough lasers to know the answer. Have any of yours just died while only used a few hours total?

 

[lasersbee]

Sorry for perpetuating an OLD thread, but how much of that limited lifespan could have been attributed simply to natural degradation of the diode which occurs even in an unpowered state?

So...you're telling me that if I store my quality laser and use it only a few times a year, it should theoretically last forever? I understand that ALL electronics degrade over time...especially the dielectric components like capacitors. However, you apparently own enough lasers to know the answer. Have any of yours just died while only used a few hours total?

That would depend on the environment when the
Laser is turned 'ON'.
Electrolytic Capacitors can dry out... but I can't see
a ceramic capacitor drying out.

I'd be interested to see/read a link or datasheet that
shows/proves the amount of degradation of un-powered
electronic semiconductor parts that are not in adverse
environments.


Jerry

 

[GSS]

Come on ultimateK, how many of us just in for the hobby seal up are pointers to the extreme? edslittle, asked more of a crystal degrade over time which has been a topic quite a few times, and alot seem to agree as their 532's just aren't performing the same after a long lay off sitting in the box.
There are some threads out there with members opinions.

 

[edslittleworld]

That would depend on the environment when the
Laser is turned 'ON'.
Electrolytic Capacitors can dry out... but I can't see
a ceramic capacitor drying out.

I'd be interested to see/read a link or datasheet that
shows/proves the amount of degradation of un-powered
electronic semiconductor parts that are not in adverse
environments.


Jerry

Maybe, not EXACTLY what you're looking for...but this link discusses the increased power requirements for diodes as the age for the same output. I assume the additional power required will be generated as heat and the start of a very slow-paced "thermal runaway":

Laser Diode Lifetime, Failure & Reliability :: Radio-Electronics.Com

 

[ultimatekaiser]

So...you're telling me that if I store my quality laser and use it only a few times a year, it should theoretically last forever? I understand that ALL electronics degrade over time...especially the dielectric components like capacitors. However, you apparently own enough lasers to know the answer. Have any of yours just died while only used a few hours total?

Well, nothing lasts forever...but being facetious aside...if you only ran it once a year, vs once a month, then naturally the lifetime will be in accordance, but not they don't degrade on the shelf. as mentioned by jerry, there are some components that may go bad like the electrolytics but as a general whole, not usually, and not on any timescale that matters, it'd take years of sitting, and occasional use does help with this problem a lot.

As for random failure-sure. I've had diodes in professional setups die at all clock ticks. I've had some die at very low hours, I've had some last well beyond their rated life. As a matter of fact, I just replaced a diode in one of my melles griot RCS lasers at 570 hours ish! I have others at thousands of hours that are like new. You can predict, but you can never tell for sure just how long they'll last. remember that a laser diode is a high stress device...you're ramming amps of power through something maybe a few tens of microns in size! The paper you reference is a basic article, and I actually have the full version as a paper somewhere. It can be found by googling. lots of factors affect laser diode life, but sitting isn't one of them. I have diodes as old as I am that still work like the day they were made that have sat for tens of years that were never put into service.

Hell, I have power supplies that are from the 60s that still work, and before you ask....NO parts were ever replaced in them. They're all original. In fact my 119 supply, the one in question, is so old it has tubes in it!

Come on ultimateK, how many of us just in for the hobby seal up are pointers to the extreme? edslittle, asked more of a crystal degrade over time which has been a topic quite a few times, and alot seem to agree as their 532's just aren't performing the same after a long lay off sitting in the box.
There are some threads out there with members opinions.

Now you're just being rude. and yes plenty of us have sealed modules. pretty much any CNI, or professional laser is hermetically sealed for both lifetime, and tampering reasons. That being said, yes some of us DO seal our stuff, and I have done so with many of my DPSS that I've made/repaired, but it's more for protection of the parts than anything. I don't do it with direct diodes, but its not really needed as pointed out. Crystals do not degrade from sitting. A YAG or ruby doesn't change from the day it's made. You can damage it from misuse (optical damage or physical trauma) but simply using it in a proper manner doesn't harm it. KTP, and many other doubling crystals also don't care. There are some select crystals like an LBO that can be damaged from moisture, but they're a seperate case, and usually only used where no other option is available, and are generally used in a sealed environment for this reason.

Your handheld isn't going to decay sitting on the shelf, it just wont happen. and a minor loss of a few milliwatts on something that isn't thermally controlled and has irregular output is hardly conclusive. If the environment isn't appropriate when it starts up, then thermal shock and other things may come into play, but in and of itself, it isn't going to die simply from the act of sitting.

 

[Benm]

That would depend on the environment when the
Laser is turned 'ON'.
Electrolytic Capacitors can dry out...

Well, they can, but good ones don't at room temperature really.

If you look at vintage equipment, like hifi stuff from the 70s or 80s, the capacitors in those are often still fine and more or less within spec today.

At higher temperatures they often fail at some point, but just sitting idle those things last for decades at least. If you take a elco out of something like a hifi system built in the 80s that has been sitting on a shelf for a decade or two it will still measure as good today more often than not.

A big difference is that things were built larger back in those days allowing for more ventillation and hence capacitors running cooler compared to todays miniature switchmode supplies.

That said i do have some (50 Hz transformer based) power supllies that are somewhat cramped for space from the 90s that still work without any problems to this day.

 

[ultimatekaiser]

Agreed entirely, many of my old supplies from the 80s and 90s are just fine...heck I have an old analog oscilloscope (a tek 465b) that still works just fine too. don't think anything's ever had to be replaced on it.

 

[Razako]

In my experience, parts like capacitors tend to go bad as a result of use more than age. In a laser power supply which hardly ever gets turned on, they'll probably endure for a long time. They tend to go bad more often in electronics which see a lot of use such as audio power amplifiers, old radios and the like.

 

[GSS]

ultamiteK, wasn't meant to be rude, its just more for what I see how the just hobbiest like me might store their pointer or portable builds. I just tend to cap the front and keep them in a box.
Razako, didn't you have "Optotronic's" RGL 532 portable that lost some output over time and it wasn't due to over use?:thinking: If I remember correctly you just took it out one day and it just didn't perform the same?

 

[ultimatekaiser]

In my experience, parts like capacitors tend to go bad as a result of use more than age. In a laser power supply which hardly ever gets turned on, they'll probably endure for a long time. They tend to go bad more often in electronics which see a lot of use such as audio power amplifiers, old radios and the like.

yeah, usually seems to be usage and heat related. Electrolytics are like batteries, they do start to crystallize or dry up over time from the above, and eventually they bulge and then leak. I've had to replace a fair few. those and tantalums. ceramic disk ones generally are tough and rarely do I have to replace them unless something is very wrong.

ultamiteK, wasn't meant to be rude, its just more for what I see how the just hobbiest like me might store their pointer or portable builds. I just tend to cap the front and keep them in a box.
Razako, didn't you have "Optotronic's" RGL 532 portable that lost some output over time and it wasn't due to over use?:thinking: If I remember correctly you just took it out one day and it just didn't perform the same?

I figured it wasn't meant to be. and frankly just capping it and storing it in a cool dry place is best. I'd be interested too, but there's lots of reasons why power loss can happen. it'd be hard to determine just on a whim.

 

[Razako]

ultamiteK, wasn't meant to be rude, its just more for what I see how the just hobbiest like me might store their pointer or portable builds. I just tend to cap the front and keep them in a box.
Razako, didn't you have "Optotronic's" RGL 532 portable that lost some output over time and it wasn't due to over use?:thinking: If I remember correctly you just took it out one day and it just didn't perform the same?

Correct, and I never really figured out why. When I last metered it, the laser was only putting out 150-190mw despite being rated at 300mw. I'm not sure when exactly the output loss occurred because this laser goes way back (Was my 3rd laser purchased way back around 2008ish). It probably only has around 20 hours of use at max, which is far below the rated 80,000 hour diode lifespan. I can only assume that the crystals must have degraded, something got bumped out of alignment, or a component in the driver has drifted out of tolerance.

I also had a blue RPL which drifted so far underspec that I eventually took it apart to use the host for something else. It was rated at 35mw peak and after 7-8 years it had fallen down to like 15mw peak, and that was only after warming up for several minutes. For the first 2-3 minutes on a cold start it would barely lase.

Not saying that ALL optotronics products are bad, but something was definitely fishy with my 2 RPL's. I wonder if it was just a bad batch with defects that would cripple the lasers in the long run. I never abused the lasers or ran them past their 5 min rated duty cycle. Never dropped them or bumped them into anything.

 

[ultimatekaiser]

Did you ever check the mode? If it was accompanied by a power loss and it was an alignment problem usually there will be a symptom in the beam profile, but not always. Could also be a temperature problem, or as you mentioned it could be an electronics problem. My old Aries eventually had a problem with alignment, as it turned out the crystal hadn't been fastened by CNI correctly and so it slid out of position slightly.

Especially after a cold start I usually don't meter things first run for handhelds. I usually give them one or two short runs at maybe 10-40sec to get the module slowly up to temp first. Some of them, especially my blues can behave very weird when they're cold even though they don't feel cold by hand.

I highly doubt the crystals have been damaged from normal operation. A couple of watts of hours not enough to damage the cryatals. I have had a couple of the cases were a laser got too hot though and so I turned it off and it never quite made it up to power again after the fact, possibly diode damage..Especially with older pump diodes. Newer ones are considerably more robust. One time I found one that was working perfectly fine but the emitter junction wires had sagged. Lifted them carefully with a sheet and it worked again.