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FrozenGate by Avery

Little help please?

C

craigrose

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Jul 13, 2011
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I recently finished constructing a 405nm, 120mw laser using this module

Laser module w/ heatsink and AR coated glass lens (405-450nm) [M0019] - $12.99 : Modwerx Shop

and this diode

PHR-805T laser diode 405nm 100-120mW [M0025] - $9.99 : Modwerx Shop

I built my own driver circuit using an lm317. So here's the deal: I had it perfect last night. It was lighting matches in less then a second and burning the wooden worktable i had it on. So i go to fire it up today, lens is set the same, the beam appears focused, but no burning anything. What happened? Any input would be appreciated. Thanks
 





Which LM317 circuit did you use.... and how did you adjust
the LD's current and what current was your Driver set to...:thinking:

Jerry
 
If you're running off battery power, it is very possible they are run down. Linear drivers rely on battery voltage to stay within nominal range to operate, once they run down you're not getting enough voltage tot he LD to satisfy the Vf and the LM317's drop.
 
i have it running from a power supply. 8.5 volts coming in. after the driver, i had originally about 150-200 mA. then i started increasing it slowly to see if i could juice it up a bit. it was running around 500-600mA when i was done and it was burning like a dream. so could i have burnt something in the diode? it still shines just as brightly so i think the diode is fine...
 
Um...120mA max for a PHR. Most people set it to 90-100mA for longevity.

You degraded the diode. I'm surprised its still lasing.
 
i was trying to see when it would break down. Im doing a project for school. So i took temp measurements and current measurements and charted it with performance. I don't know a whole lot about the actual building process or the proper procedure yet as I'm just getting started. I believed that the diode would essentially just stop working when it broke down. so when it dies, it can still appear to work at full capacity?
 
Tech_Junkie said:
Um...120mA max for a PHR. Most people set it to 90-100mA for longevity.

You degraded the diode. I'm surprised its still lasing.
Click to expand...

I dunno, I've pushed an 805 to 145mA and it lasted me a good four months with heavy use. The 805's are more robust than the 803's. I have an 805 @ 130 in a pen right now and it run's with no kinks!
 
Fretwrecker94 said:
I dunno, I've pushed an 805 to 145mA and it lasted me a good four months with heavy use. The 805's are more robust than the 803's. I have an 805 @ 130 in a pen right now and it run's with no kinks!
Click to expand...

You need to read more. We all push these diodes waaay past their ratings. Some diodes can handle it, some dont. Its always a roll of the dice. Just because you got good results doesnt mean everyone else will too. The extra 10-25mAs dont really add up to that much extra power. And obviously Craig pushed it much further.
 
Tech_Junkie said:
You need to read more. We all push these diodes waaay past their ratings. Some diodes can handle it, some dont. Its always a roll of the dice. Just because you got good results doesnt mean everyone else will too. The extra 10-25mAs dont really add up to that much extra power. And obviously Craig pushed it much further.
Click to expand...

I understand that people get freak diodes. I know people push them past their recommended current ratings. I was just stating that you don't need a freak diode to push an 805 more than an 803.
 
i wasn't really concerned about the money, like i said the point of that little experiment was to test the durability of the diode and the amount of stress it can handle. thanks for the resources and all the input. this was a learning experience! and i haven't really gotten to the research portion of my project yet, actually I'm beginning the real meat of it in about an hour. I did enough research to learn the very basics of building and operating a laser. i was really excited to get it working and see it in action, so i neglected a little bit of the heavy details. i plan on make this a serious hobby now, so ill be sure to check everything out before i go frying things on accident and asking stupid questions about what happened XD

thanks everyone =)
 
One more quick question; the diodes of the same model number are built to the same specs, so how much of a difference can there be? Is it just by absolute chance, or is there another factor to how far you can push a diode?
 
They have to grow crystals to make the lase medium. As with all organic substances, and product productions, there are variations. Efficiency is what makes one diodes more durable then another. They are best compared to computer chips. The chips do not come out all the same, and are binned according to performance. Most laser diodes are the same. The new M-140 445nm diodes seem to be the same as the previous diodes, but with higher efficiency. The PHRs are more than likely the same.
 
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