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Disappointing experience with 445nm

Seoul_lasers

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I finally got my 445nm diode in the mail from a member here at LPF.
I have a lab driver that I can preset current that I have used in the past to drive 405nm to 660nm diodes. It has worked beautifully up until this point.

I started my diode at 250mA, which is just above lasing, I got light from it, but just a little, then turned the driver off. On the second attempt I used ~320mA.
Here is the output at ~320mA.

The diode is a bloody glowplug heater. I don't think I have ever felt a diode get so hot as this one. WOW!

I double checked the driver, wires, PSU, current and heatsink. Nothing is wrong.
Diode I suspect might have been exposed to something during transport? but what ? the diodes leads were soldered together so static shouldn't have been an issue.

Has anyone else got this too?
This is out of a Casio A130 projector. Aren't these in recall due to overheating?
 

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Prototype

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Does it still output a dot when used with a lens, or is it just a big blue splotch no matter what? These diodes are rated for a fair amount of heat, but I'd look into a larger heatsink.
 

daguin

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I'm not sure what you are disappointed with.
Is it because the diode gets hotter than you are used to?
Is it because the light isn't as bright as your thought it would be?
Is it something else?

Why are you disappointed?

Peace,
dave
 

hakzaw1

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His sig tells a lot---RIP -Croaked- died -died

not trying to be a 'smart ass'--just sayin'
 

Seoul_lasers

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No, never got it lasing. That's my point. This driver currently drives a 10x diode without issues in the same kind of housing. These are finned heatsinks!

yes, indeed I had a few diodes die on me. I have got 5 at current that are all working perfectly.
My first few were from a local guy. His drivers killed them.
They were his own.

This is a new driver with mods, courtesy of a LPE member and slipped me the mods to do. IT's been my driver since May.
 

Benm

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Well, i suppose it will get pretty hot running like that - the big heatsink it lyes on top of won't contribute to cooling. With a forward voltage of about 5 and 320 mA you're burning 1.5 watts of electrical power in a relatively small package, so its quite normal that it gets hot.
 

lasersbee

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Yeah... I don't understand the Lab driver... I see a regular PCB
Driver... not a lab driver...

a) what exactly is your problem with your LD...??

1) do you have a DMM..??
2) do you have an O'scope..??
3) do you have an LPM..??
4) Who makes your PCB LD Driver...?
5) Is it a linear driver or boost driver.. the next questions depend on the
answers..

BTW... transferring all that heat though 2 fins of that small heatsink
is not very efficient...IMO

[EDIT]
I see you aswered some of the questions while I was typing..:evil:

What is the actual current with the LD connected...

If your Driver is adjustable cleanly... I would monitor the current
of your connected LD and start at a low setting up to 500mA and
note when the LD starts lasing... It should be below 250mA...
You will only easily see the lasing transition if you use a lens...


Jerry
 
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daguin

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No, never got it lasing. That's my point. This driver currently drives a 10x diode without issues in the same kind of housing. These are finned heatsinks!

yes, indeed I had a few diodes die on me. I have got 5 at current that are all working perfectly.
My first few were from a local guy. His drivers killed them.
They were his own.

This is a new driver with mods, courtesy of a LPE member and slipped me the mods to do. IT's been my driver since May.
So what is the blue light coming out of it here?



And that "set-up" is nowhere close to heat sinking that diode

Peace,
dave
 

Seoul_lasers

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Yes, I have a DMM, no money for a scope or LPM right now.

These diode modules are lab modules and have 3 fins on them. No the driver is a "lab style OEM driver" and not a boost. It's ment to be run off 12vdc at 1.5A, uses a HFreq switching IC to change voltage depending on the load. As I said it has worked great on LOC-815s and 6-10x 405nm diodes so far.
 

Seoul_lasers

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So what is the blue light coming out of it here?



And that "set-up" is nowhere close to heat sinking that diode

Peace,
dave
that's just a dim light. Not lasing at all . I have it at 250mA here. 50mA above threshold current.

DOA diode. The big heatsink is just a rest to have the diode module sit on.
 

lasersbee

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Do the test in my [EDIT] above.. you can do it with only a DMM..
With a second DMM you could also check the voltage across the
LD..
What worries me is that you say it is a Linear Driver and then
say it has a variable switching output...
Maybe your Driver is at it's switching limits or is not filtered
properly...
I have no clue as to what your driver is...

What does you beam dot look like through a Lens...????


The other answer to you low out put will be that the LD has LEDed
and is sucking a lot of current from the driver..

I damaged my first LD and it puts out ~150mW at over 1000mA
of current.. where a good LD puts out 200mW at 370mA


Jerry
 
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Ash

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...
I have no clue as to what your driver is...

...
Faulty. :undecided:
And, of course. That tiny black heatsink will not do much in the way of cooling a 445 that runs much hotter (on avg) than a 405, or 660.
You are probably overheating your diode really fast.
Go with something at least this big:


Also, try using a boost driver set at higher currents (after of course) installing the 445LD in a proper heatsink.
 

blrock

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If a diode gets really really hot and only glows without lasing....it has popped
 

Giface

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If a diode gets really really hot and only glows without lasing....it has popped
Well, that's what mine do. Then I try to put 3 amps through them and for some odd reason the light goes out :thinking:.

Dave
 

Seoul_lasers

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I starting to agree with laserbees end hypothesis.

The driver is a Constant Current driver that has an IC to control the voltage while leaving current set a given level. I don't know if you call this linear, or what...
As I say again this driver on the lowest output setting is 200mA, which is below threshold for 445nm. It will run blu-ray fine and 650nm LOC diodes without busting a sweat.

DMM is a Voltage across the diode is approximately 5.0v @ 250mA, so it should be lasing instead it's a glowplug. (ie, it's popped)

Here is a 20x DVD LOC running off the same C.C.Driver. Output here is ~3.3v at 380-400mA.

This is a long exposure shot at 2.5sec
 

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Seoul_lasers

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Faulty. :undecided:
And, of course. That tiny black heatsink will not do much in the way of cooling a 445 that runs much hotter (on avg) than a 405, or 660.
You are probably overheating your diode really fast.
Go with something at least this big:


Also, try using a boost driver set at higher currents (after of course) installing the 445LD in a proper heatsink.
Shouldn't have been a problem at 250mA! I in no way want to run 100% into this diode without a HUGE heat sink, but at just above threshold this module should be WAY more than enough.


Back to marking. sigh. This hobby is wearing my patience out.
 




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