Milos
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- Joined
- Apr 22, 2007
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I thought it would be useful reposting since it disappeared after forum was down. . .
I've been meaning to write this thread some time ago to kind of sum up all things i experienced with many diodes I harvested from now over 40 KES-400A modules. Not only harvested, but tested a lot and praying they would perform well! So what can you really expect from this diode…
As you know, buying a KES-400 module was always, and still is a cheapest way of getting 405nm diode useful for building a hand held laser. There are few other 5-12mW diodes i came across on internet, but prices were ridiculous, and even now they are $70 or more last time I checked. Some even sell them for 10x that.
So you buy an entire PS3 optical assembly and after grounding yourself and only about 20 seconds of taking it apart, you get your little diode for $30 or less!
- One of the things I found right at that initial stage is that it's very good idea to cover the window of diode with a piece of scotch tape (cut a ~2x2mm square). It will save you trouble of later cleaning this delicate part, and if dust or dry glue falls on it. This is going to protect it from dirt for next step which is cleaning it from dried glue. This step is another good idea because the glue is clear and hard to see, but it can mess you up when inserting diode into the module (such as common aixiz modules). It can cause your diode not to sit straight in the module, which will result in beam not being projected through the lens straight, or fully, and it will look as a incomplete or crooked "dot" .
You should carefully scrape this clear glue with razor knife off the edges and top of the diode base only(widest part). It will at least help you insert this diode into module smoothly. Some of the aixiz modules are quite tight.
- Now a bit about this diodes performance, which is what everyone is most concerned about.
Everyone by now knows how much they vary in performance from each other. I think this might be a good reason true official spec sheet hasn’t been available. I also think the way we use this diode is not what it was ever meant to do, so we are all experiencing different results. I heard more than one credible opinion that PS3 diode is not made only (or always) by Nichia, but by Sony as well.
Interesting thing I found is that diodes from first 2 batches reacted to current changes between 38mA and 42mA a lot more than they do now. I used to be able to increase power by 10mW in some cases within this little range. All of a sudden this “behavior” stopped in last few batches of 10 I bought. More than half of diodes I recently got barely increase by 2-4mW going from 38-42. I even push further just to test up to 46mA, and barely any change in optical power. Many diodes now don’t even react to such small increases in current, and stay between 1-2mW difference between 35-41mA range.
-Most of diodes diodes I made into laser pointers so far, perform between 8mW and 15mW. at 37-41 milliamp of current. You have about 50-50 chance to get one 8-12mW diode and 12-15mW out of 2 units.
I noticed that they under perform in the first couple of ONs lasting less than a minute. Does this mean they need a short "break in period" ? My experience definitely prove this. Almost every diode I power up first couple of times reads 2-4mW less than the day later ON. I double checked currents, and batteries. Just another interesting observation.
Out of lets say 12 diodes, 2-3 will output over 18mW at 40mA. Also about 2-3 will output below 7mW.
Sometimes you get one that outputs 3-4mW at 40-41mA and at first I though I would throw these as they SUCK big time, but those diodes are just freaks, and need more juice to work! I slowly increase current to 60mA and they reach about 15mW. I went as far as 100mA and 2 diodes are running between 20-32mW.
Those diodes are rare.
So, If you get like less that 4mW in common current range, don't be sorry right away. It might not be a bad diode! Give it slowly more juice, and see if you actually got this freak diode.
No one knows how long they will live, but I have two already that are eating 80 and 95mA and are still alive after 5 weeks. They drooped in power after few days to settle around 24 and 22mW. I did a long ONs though, and repeatedly.
lets see, what else . .
Lets mention few things about projected pattern.
There are at least a couple of patterns I noticed this diode projects straight out (without lens)
One is 99% identical to the common red diode projection.
The other is similar, but more ribbed as these "lines" are more separate. There is a main bright line in going through center, and than gap on each side and two more quite bright ones.
in either case, after putting lens, these patterns don't make much difference. What does make difference, is how projected dot looks at distance. If beam converges before hitting the wall, there is a good chance it will look like a crappy "dot" I haven't investigate this enough, but I'm sure some of you did. Please post your findings on best collimating technique.
There is also this outside pale yellowish pattern that many of us have noticed. Dave (Daguin) has been quite on top of this phenomenon. I think it has something to do with how parts of this diode inside lase, and how efficiently they do. Its always on the sides and around the middle. Not all of the diodes have this, but its safe to say its a common thing.
I hope more of you will add info to this thread as it can be useful reference, for at least some months to come.
Till next time..
Yours truly
I've been meaning to write this thread some time ago to kind of sum up all things i experienced with many diodes I harvested from now over 40 KES-400A modules. Not only harvested, but tested a lot and praying they would perform well! So what can you really expect from this diode…
As you know, buying a KES-400 module was always, and still is a cheapest way of getting 405nm diode useful for building a hand held laser. There are few other 5-12mW diodes i came across on internet, but prices were ridiculous, and even now they are $70 or more last time I checked. Some even sell them for 10x that.
So you buy an entire PS3 optical assembly and after grounding yourself and only about 20 seconds of taking it apart, you get your little diode for $30 or less!
- One of the things I found right at that initial stage is that it's very good idea to cover the window of diode with a piece of scotch tape (cut a ~2x2mm square). It will save you trouble of later cleaning this delicate part, and if dust or dry glue falls on it. This is going to protect it from dirt for next step which is cleaning it from dried glue. This step is another good idea because the glue is clear and hard to see, but it can mess you up when inserting diode into the module (such as common aixiz modules). It can cause your diode not to sit straight in the module, which will result in beam not being projected through the lens straight, or fully, and it will look as a incomplete or crooked "dot" .
You should carefully scrape this clear glue with razor knife off the edges and top of the diode base only(widest part). It will at least help you insert this diode into module smoothly. Some of the aixiz modules are quite tight.
- Now a bit about this diodes performance, which is what everyone is most concerned about.
Everyone by now knows how much they vary in performance from each other. I think this might be a good reason true official spec sheet hasn’t been available. I also think the way we use this diode is not what it was ever meant to do, so we are all experiencing different results. I heard more than one credible opinion that PS3 diode is not made only (or always) by Nichia, but by Sony as well.
Interesting thing I found is that diodes from first 2 batches reacted to current changes between 38mA and 42mA a lot more than they do now. I used to be able to increase power by 10mW in some cases within this little range. All of a sudden this “behavior” stopped in last few batches of 10 I bought. More than half of diodes I recently got barely increase by 2-4mW going from 38-42. I even push further just to test up to 46mA, and barely any change in optical power. Many diodes now don’t even react to such small increases in current, and stay between 1-2mW difference between 35-41mA range.
-Most of diodes diodes I made into laser pointers so far, perform between 8mW and 15mW. at 37-41 milliamp of current. You have about 50-50 chance to get one 8-12mW diode and 12-15mW out of 2 units.
I noticed that they under perform in the first couple of ONs lasting less than a minute. Does this mean they need a short "break in period" ? My experience definitely prove this. Almost every diode I power up first couple of times reads 2-4mW less than the day later ON. I double checked currents, and batteries. Just another interesting observation.
Out of lets say 12 diodes, 2-3 will output over 18mW at 40mA. Also about 2-3 will output below 7mW.
Sometimes you get one that outputs 3-4mW at 40-41mA and at first I though I would throw these as they SUCK big time, but those diodes are just freaks, and need more juice to work! I slowly increase current to 60mA and they reach about 15mW. I went as far as 100mA and 2 diodes are running between 20-32mW.
Those diodes are rare.
So, If you get like less that 4mW in common current range, don't be sorry right away. It might not be a bad diode! Give it slowly more juice, and see if you actually got this freak diode.
No one knows how long they will live, but I have two already that are eating 80 and 95mA and are still alive after 5 weeks. They drooped in power after few days to settle around 24 and 22mW. I did a long ONs though, and repeatedly.
lets see, what else . .
Lets mention few things about projected pattern.
There are at least a couple of patterns I noticed this diode projects straight out (without lens)
One is 99% identical to the common red diode projection.
The other is similar, but more ribbed as these "lines" are more separate. There is a main bright line in going through center, and than gap on each side and two more quite bright ones.
in either case, after putting lens, these patterns don't make much difference. What does make difference, is how projected dot looks at distance. If beam converges before hitting the wall, there is a good chance it will look like a crappy "dot" I haven't investigate this enough, but I'm sure some of you did. Please post your findings on best collimating technique.
There is also this outside pale yellowish pattern that many of us have noticed. Dave (Daguin) has been quite on top of this phenomenon. I think it has something to do with how parts of this diode inside lase, and how efficiently they do. Its always on the sides and around the middle. Not all of the diodes have this, but its safe to say its a common thing.
I hope more of you will add info to this thread as it can be useful reference, for at least some months to come.
Till next time..
Yours truly
