Re: FS: >110mW PHR, >140mW 4x & >170mW 6x Blu-Rays
Helioplasma said:
I'm starting to get impatient hehehe.
You have nothing to be impatient about. I told you when i get more 6x's. That's when i get them, and that's when i will ship your upgraded laser back to you.
You should be HAPPY you're getting a 6x at all!
I paid $350 for my first, and waited over a month for it! But i was still happy, and i NEVER regretted it!
Helioplasma said:
I forgot to ask you something : 6x can handle higher currents, but will there be a stricter duty cycle?
No.. You see, contrary to the popular belief (aka "The Duty Cycle Monster" myth), higher power does NOT mean a shorter duty cycle. Higher power means a shorter life!
Duty cycle is only required, when a diode is overheating. And when it is not overheating, all a duty cycle does is, it makes you use your laser less.
That way it can actually prolong the life of a diode in days, or even months, but in hours, the difference is actually the opposite - it can be shorter, from more power-up/down related stresses.
In reality, the difference in heat created by a 6x at 160mW and a 6x at 200mW is not that big. Let's look at my old 6x for example..
The heat is very easy to calculate. I have a full P/I/V plot of my diode (as will you, of your diode), all the info is in it, and the heat created, is simply the difference between the power going in (electrical), and the power coming out (optical). Since it is impossible for less power to come out, than what goes in, the difference has to go somewhere too - it is converted to heat. The ratio of optical vs. thermal power created by a diode is called "efficiency"....
My old 6x at 150mW:
Pin = 0.180A x 5.21V = 0.9378W
Pout = 0.160W
Heat =
0.0.7778W
My old 6x at 200mW:
Pin = 0.215A x 5.38V = 1.1567W
Pout = 0.200W
Heat =
0.9576W
Difference between heat at 200 and 160mW = 0.1789W
So at 160mW it only produces 18.7% less heat than at 200mW. That doesn't really make much of a difference, when it comes to the temperature of the diode, in a well heatsinked laser. But at 160mW it will live a LOT longer than at 200mW, because at 160mW after a plastic lens, the raw output is below the diode's pulsed ratings, while at 200mW after plastics, the raw output is quite a bit above pulsed ratings (over 250mW!).
For a diode to survive, it has to be capable of withstanding it's own output power. Theoretically, every diode can be set to ANY power. But the quetion is - how long.. A 5mW diode can produce a short burst of 100mW, but it will fry in a split second. Or it may fry half way to 100mW..
For the manufacturers to make more powerful diodes, they have to make diodes with end facets, that can withstand a higher optical flux (among other things). If the tiny mirrors can't withstand the optical energy, they can start burning up, and once a spot on it burns up, the diode is practically dead. That point will stop reflecting light and start absorbing it, and become a hotspot, increasing the "strain" on the areas around it. Once a large enough area fails, it takes the whole diode down with it, almost in an instant. That is what we call CO(M)D - Catastrophic Optical (Mirror) Damage.
Basically, the mirrors have to be capable of withstanding the diode's output power. If they are not, the diode will die. And usually, diodes don't like to be set above their pulsed ratings.
Surprisingly enough the 6x can survive even 200mW after plastics for a very long time, but at a certain small risk, which is always present....
Helioplasma said:
What diode lifetime can I expect if I ask you to run mine at 180mA (with custom lens obviously)?
I can't tell you the specific lifetime in hours just yet. I will have to murder three 6x's to figure that out. And i can't do that from the first package, so it'll have to be from the second one.
However, the one i bought almost half a year ago.. It cost me a fortune. But i risked it and set it to 200mA. I used it A LOT. More than you ever will.
When i use a PHR at 160mW that much, it is dead in one to three weeks! But my 6x is still alive. On top of that, i used it for numerous experiments, when it was on for a lot of time. Heatsink testing, lens testing, you name it... And this one time, i fell asleep with the 6x ON. It turned off when the battery protection kicked in an hour and a half later! But it's still alive and well!
Based on that, i believe a 6x in the hands of an average user would last a year if not longer, even if set to 200mW. However the higher you go, the higher the risk, that a weaker one will suddenly reveal itself by popping unexpectedly....
You have to know, there is always a small risk, when using diodes outside their ratings. You never know what will happen. With testing, you can establish some general guidelines, where the risk is small and acceptable. But even within the diode's ratings, a weakling can still pop - if you read a diode datasheet, it will say, that statistically one diode out of so many can and will always fail, no matter what you do.
From my experience with other 405nm diodes and my personal 6x, i believe 170-200mW is a reasonably high range for 6x's. Altho many engineers would tell you it's too much - to set it to 130mW! But i know you all want power! ;D
So i try to find a balance between power and acceptable risk... I don't like going too high, or i'd be selling 150mW PHRs. So if i am willing to set a 6x to 180mW for a good, high, but still decently lasting power, then you don't have to worry too much. Altho my Maximum Reliability recommendation would be 165mW, because there the raw output is at the diode's pulsed power raitng. 200mW is my Max Power recommendation, 180mW is almost in the middle..
Problem is, no one respects 165mW anymore these days, altho it is a LOT of power! But people expect that much from PHRs! But i have a personal high power PHR laser, in which
i had to replace the PHR diode, set to 150-170mW, almost ten times, during the same time in which my 6x at 193mW just kept going! And that with the same use or even higher on the 6x, since i use the most powerful laser the most!
With a PHR at 165mW, you get a high power laser you can have, but if you actually use it, you don't have it for very long. With a 6x, you get a high power laser you can USE. As much as you like! And it'll just keep going...
PHRs (and seemingly most 405nm's) have this unusual ability to be set to powers, where any normal diode should pop instantly, at first powerup, But they just keep on going! Often long enough to fool you into thinking they will survive (happened to me every time). They had the ability to show us, what high powers look like, but only 6x's can actually also deliver those powers with any kind of reliability. The PHR is a
reader diode. The 6x is a
WRITER! A 6x speed writer!
Helioplasma said:
I remember tbe PHR didn't pass the 15 hour bar running at 115mW (130-140mA is it ?). At what mA do you usually set your lasers before you sell them ?
No, you mixed something up here. The 27 PHR diodes i killed in testing were set between 150-170mW. They lasted 3-15 hours, 20 hours in one case (= lifetime when cycled - much longer when just left on continuously).
If they would only live 15 hours at 115mW, i would NOT be setting them this high! But most PHRs can survive 115-125mW for a decent duration of average use.. In some cases they will even outlive the user's interest. That's why this is the power i use for PHRs - the risk is low and acceptable IMO.
But just like i mentioned above, there are always weaker diodes, that won't survive what most will. You have to understand, we are squeezing these for all they are worth (and more).. There is no way to identify the weaker ones up front.. You only know they WERE weaker, once they are dead..
Helioplasma said:
PS : when you send my laser back, don't forget to send me my hard pencil case, coz it's the only one that can hold four lasers at the time
Of course, your laser is still safelly stored in there. Don't worry about it..
(thanks Jayrob and Scopeguy20!)
