focus/artifact

[wicked1]

I got a diode today to replace one I killed last week. When I focus it, there are a few artifacts. to one side of the dot is a small line, then another longer line. (they're more like long smudgy dots than lines, if that helps you picture it)

I didn't notice the same thing on the diode I had last week, but it died before it was dark, so I might not have noticed.

Are artifacts like this common in diodes? The window isn't cracked, and it is clean. I tried different lenses, and it made no difference.

This is in a meredith glass lens assembly.

I have one more 9mm adapter, but I don't really want to press my other BR diode into it! I don't think I could get the diode back out of the adapter, and I might not want to use a second meredith lens.
If it is most likely a defect w/ this diode, then I'll press my spare diode into one of the adapters.

Thanks!!

 

[rog8811]

PS3 or 360HD?
I have had a number of PS3 ones with odd artifacts, it makes me wonder whether the sleds we get are reject ones :-/
I have never had one that was so bad as to be unusable though...

Regards rog8811

 

[Kenom]

easiest way to determine where the artifact is, is to remove the lens and view the unedited light.

 

[wicked1]

It looks fine w/out a lens! Just a blurry rectangle, like any other unfocused diode laser. It's as I bring it into focus, is splits into the main dot, and the artifacts.

It's certainly usable. I just turned the laser on in the daylight again, and I don't see it. It was very noticeable at night, tho.

It looks to me like it could be an internal reflection.. inside the meredith module. But, I tried the lenses/retainters, etc, from another module. Maybe its a reflection off the edge of the diode can itself. I dono

So, chances are my 2nd diode might not have the same issue?
I might have to try it... hmmmm..... I wish I didn't have to practically sacrifice it, just to get it in a lens assembly.

 

[rog8811]

From what I have seen the yellow seems to be an internal reflection from the base that the laser chip is mounted on.

Regards rog8811

 

[flogged]

{If you want a diagnosis, try to post a picture of the artifact)

OK.. Artifacts are the norm around these diodes. In good light they may be hard to notice. A severe test for seeing them - go into a completely dark room and let your eyes dark adapt for a few minutes, then project the laser spot onto something dark, like a speck of electrical tape on the wall (hopefully the tape will not start smoking ;D - use disgression) then look around it. Some patterns only show up up close, others are easier to see when the laser it at least 10-20 feet away.

Anyway, what diode are you talking about here?

Both of the XBox diodes (803 & 811 sleds) have artifacts - I've got healthy pointers built around each diode and can attest to this. Both using Meredith lens assembly also. The 811 sled ('low' powered diode) has a very prominent rectangle of violet and yellow around the spot, with diode spot along an edge of it. I think this is caused by something fluorescing in the diode sandwich (I've posted pictures of this in other threads). Both 811 diodes I harvested had this, it's something intrinsic to their construction. The 803 diode ('high' powered) has some smudges around one end the diode spot, which I believe are caused by reflections off the brass pedestal the diode is glued to.

Remember, the total power output of these diodes is twice the rated power - a 100mW diode has a total output of over 200mW - you just get one end of it! The other end gets blasted back into the diode can, where it typically hits a photodiode. That's what the third pin on the diode is for (monitor photodiode) - it's used by APC (automatic power control) supplies which attempt to keep the actual output of the LD constant as it changes temperature, by adjusting the current as needed. This is very important for things like burners - it doesn't really matter for a pointer. Point is, there's a lot of backscattered and reflected light off internal structures in the diode can, and from the diode window, which can cause artifacts. In any case they're cosmetic - as long as the diode spot is good clean ellipse when focused (burning will tell you true - if the diode is funky and not single mode it aint gonna burn much unless it's really powerful, in the watt class)

About the meredith 9->5 mm case adapter. IMO, it's very important you completely press fit the diode into this! I even go so far as to thermal glue in into place, and then dab thermal glue to mate the top of the brass diode flange to the edge of this adapter, to improve heat flow out of the diode. This metal bit is the first link in whatever heatsink you've got, and the most important. Next I thermal glue this adapter to the back of the Meredith case to assure it stays centered while focusing, and to assure heat can efficiently wick to the big heatsink. You don't have to use glue, but at least some thermal paste is recommended. It doesn't matter if you've got a honking big heatsink if there's a poor thermal path from the diode to it. And remember, all things being equal, a cooler diode will live longer than a hot one, exponentially so.

 

[Kenom]

Here are the artifacts that I see in my ps3.

 

[wicked1]

ARG!!
I cracked the lens on my 2nd diode when I was pushing it into the meredith adapter.
Then I tried to grind around the sides of the can, adapter, and all, to get the top of the can off.
I did succeed in doing that, but all I'm left w/ is a windowless LED

 

[GooeyGus]

Next time it happens, send it to me and I'll fix it up for ya. I have a can opener designed to pull the can off safely.

 

[rubberband]

wow kenom i have never seen a blu-ray that bad.

 

[flogged]

ARG!!
I cracked the lens on my 2nd diode when I was pushing it into the meredith adapter.
Then I tried to grind around the sides of the can, adapter, and all, to get the top of the can off.
I did succeed in doing that, but all I'm left w/ is a windowless LED

Yeah, it's hard to get those tiny 5mm diodes into that brass bit. Sounds like you were pushing from the top of the diode - a big no-no. I use two pliers to do this. Make certain they are only gripping the brass diode flange/heatsink, the other half of the pliers is on the bottom of the Meredith adapter. The diode can and window (not the brass bit) are rather fragile, not meant to be subjected to blows or mechanical shock. Sometimes I use a knife to slightly enlarge the diameter of the meredith part before the press fit.

 

[rog8811]

On the Aixiz modules the hole for the top can of the LD is a clearance fit so the only location is on the flange, is the meredith different in this respect?

Regards rog8811

 

[flogged]

Well, I'm not familiar with the AixiZ stuff. The Meredith assemblies are meant for 9mm cans. In order to get a 5mm can to work, it needs to be press fit into this adapter. The bottom of the diode gets pressed into the top of the bit, then the bottom of this bit gets centered into the LDC cylinder. It works well, but I've found it necessary to thermal glue diode+adapter into the housing to keep it centered, as well as to keep it from rotating when focusing the unit.

 

[wicked1]

How I cracked it....
Those meredith adapters are deep. Pressing the diode flush w/ the adapter leaves a lot of space above the diode.
I took a little screw and used it to press the diode all the way in the adapter.
I was using pliers to press it in, and the front of the diode got push all the way flush w/ the top of the adapter. The edge of the pliers was just barely sticking into the adapter opening, so when I pressed the diode in, the pliers smashed the window.

 

[flogged]

If I understand you correctly this is not how I've been doing it. I only press the brass flange of the diode close to flush with the top of the adapter - the top of the diode can sticks out. I don't claim to know if this is correct, but I've done this for two violet builds and one red build. Seems to work. It's easy to get focus set for infinity this way, I don't have to screw the lens in anywhere close to all the way, there's a lot of threads showing. I can usually get the focus down to around 6-8" before the spring loaded assembly pops out.

Here's picture of my first 803t diode, which died when a wire popped loose from the cap to the diode, discharging the cap and killing the diode . I scraped away a bit of the thermal epoxy so you can see the brass diode flange is not quite flush with the top of the adapter. You'll also note the thermal epoxy, there to hopefully help heat exit to the adapter.

I'm cleaning up this Meredith adapter so I can reuse it now.

 

[flogged]

Disregard the above picture - here I've been plugging these things in backwards! See this thread, second page:http://www.laserpointerforums.com/forums/YaBB.pl?num=1212443308