LPC-840 discussion thread

[styropyro]

So what is the best 650-660 single mode as for output, beam quality and price, also is there a deal on them by the dozen?

10x Mitsubishi LPC 840 650nm 400mW 500mW Red Laser Diode TO18 5 6mm | eBay

I'd recommend this instead: Mitsubishi ML101U29 660nm 300mW 400mW CW Red Laser Diode 10 Pcs | eBay

These diodes are stronger than the "LPC 840" and are a third of the price. With a good lens you can get over 300mW of single mode output while still keeping some lifetime, and you can push them even harder at reduced lifetime. The nice thing is that if you blow one, it's only a $3 replacement.

 

[bdgreenb]

I agree! I have build tens of builds with these and was not impressed with the 840. I have discovered that the 29's have a pretty wide possible output difference though. Every now and then you'll get one that pumps out 350+mw on the exact same set up that getting just over 300mw on another, and conversely you might find ones putting out 270ish mw

I build these almost exclusively with lm317s w 2.2 ohm resistors

 

[Pman]

How are those any better than the 826? Ive never had an 826 not put out at least that much if I wanted it too.

 

[Shakenawake]

I'd recommend this instead: Mitsubishi ML101U29 660nm 300mW 400mW CW Red Laser Diode 10 Pcs | eBay

These diodes are stronger than the "LPC 840" and are a third of the price. With a good lens you can get over 300mW of single mode output while still keeping some lifetime, and you can push them even harder at reduced lifetime. The nice thing is that if you blow one, it's only a $3 replacement.

really? 300mW and maintain life? I ask becauce I've had a few lpc 826s die after a while putting out just a bit over that. would you happen to know how the divergence compares to the lpc 826? because that's one of my favorite things about it. I'm going to get it fixed again here soon, thankfully the diodes are cheap as you said, but if these are better in power and divergence, I'll get one of them instead.

 

[paul1598419]

I've got another one (LPC-840) on the way. I do have one in a 501B host set under 400 mA that outputs 365 mW and is consistently good for long duty cycles of three to five minutes. I plan on trying to get more out of the next one.

 

[bdgreenb]

Lens makes a big difference. I'm talking builds with acrylic lenses

edit: In my experience acrylics allow the lowest amount of output. My original post was merely to show the inconsistency of output in these diodes, and was by no means to be a measure of the actual output potential of these diodes.

 

[RedCowboy]

Thanks for the tip SP, I will order those.

I have many 660's, many with glass from various sources and I love the deep red color on a rainy/foggy night, and the beam is what we wish every other laser was, near perfect.

I started 10 years ago with 80mw 660's and then on up, along the way I have had and still have some dam tough ones, but I don't know what they are model number wise.

The audio CD uses a 780nm and the regular DVD the 660nm, and the 405 BluRay.

I don't know if there is any time left for a faster write 660nm or 405nm to be produced before static memory takes over, but we could see one.....what's in the high speed DVD duplicators?


Anyway a DVD holds 4.7 G and I saw thumb drives at wallyworld 128 G for 32 dollars and that's not even the best deal, so it's not to far away until laser disc start being replaced and these diodes may well go away with them.

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Another thing I have wondered is if the emitter size of 1 is better than the other?
I know they write tiny on the disc, but the lens and distance is short. so is one 660nm diode or 405nm diode built with a smaller emitter that the others?

 

[paul1598419]

Lens makes a big difference. I'm talking builds with acrylic lenses

I've got all kinds of single element aspheric lenses, but I don't know of any acrylic ones. If they are out there, do you have a link? As far as the ML101U29s go, I have used them for years too and they are pretty much limited to around 300 mW. I think I still have about 4 or 5 left somewhere. They are dirt cheap, but I haven't found them to be the top of the line for power. I'm interested in the acrylic lenses if they are single element as that will be the only ones that might prove a bit better.

 

[RedCowboy]

The throw away lens that comes with the 12mm blank modules, they make a good beam but rob a little power, if used in a multi watt build they will melt, but at 300mw they stand up to their own energy absorption.

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Not wanting to get to far off topic, and this has been done before I know, but what's next? Will we see a stronger single mode 405 diode?

OK the 660 DVD's are single layer typically and 4.7 GB but......
I just read that the Bu-Ray is dual layer and holds 50 GB, I did not know it was that much.......it would be nice to see a 64x 405 burner.

Also there is more that can be done with laser disc.

The Holographic Versatile Disc (HVD), described in the ECMA-377 standard, has been in development by The Holography System Development (HSD) Forum using a green writing/reading laser (532 nm) and a red positioning/addressing laser (650 nm). It is to offer MPEG-2, MPEG-4 AVC (H.264), HEVC (H.265), and VC-1 encoding, supporting a maximum storage capacity of 6TB.[67] No systems corresponding to the Ecma International HVD standard have been released.[68] Because the Blu-ray Disc format is upgradable it poses challenges to the adoption of the HVD format.

6 TB WOW

4K Blu-ray discs and players will become available in the first quarter of 2016, having a storage capacity of up to 100 GB

Hmm, it seems the disc may not be dead yet.

This was interesting.

DATA SOURCE : https://en.wikipedia.org/wiki/Blu-ray
https://en.wikipedia.org/wiki/DVD

 

[paul1598419]

I have a bunch of those lenses, but quit using the modules in favor of the copper ones. I can test this out tomorrow to see if they are better, or even comparable, to the single element aspheric glass lenses.

 

[Pman]

Paul, if you buy the copper modules from Jordan those lenses come with them and it's why most of us builders have a lot of them. I personally only use them for builds under 500mW and almost always for cheap diodes like the 150mW 405nm and 826. They work just fine although I've had to use small spacers inside the focus knobs to get the lens closer to the diode for infinity focus.

 

[paul1598419]

Thanks, Pman. I have them from many sources including Jordan. I am going to try to find out if these are somehow better than what I've been using for lenses in these builds of 500 mW or less.


Edit: I just got finished comparing the glass single element lens to the acrylic lens that is sent along with Nickel plated brass modules of the ones from DTR and it is no contest at all. I used an S1 lens from an earlier group buy and tweaked the output a little to get 382.6 mW. The acrylic lens output was a disappointing 220 mW. I let the host cool for 15 minutes between measurements. So, my question is why is anyone using these acrylic lenses again?

 

[bdgreenb]

they are cheap. I don't use them on anything I really have big plans for, but for cheap on the go diy pocket lasers they are sufficient as I don't really care if they get scratched or dirty.

 

[paul1598419]

I get that, They are actually free as I never thought of using them at all. But, the S1 lenses from the GB were about $3.50 IIRC and they give so much more power output than these cheap lenses. About 73% more and the divergence is great too. Even the ones that I had on the GB before thejoker301 took it over are great.

 

[CaliKirk]

I get that, They are actually free as I never thought of using them at all. But, the S1 lenses from the GB were about $3.50 IIRC and they give so much more power output than these cheap lenses. About 73% more and the divergence is great too. Even the ones that I had on the GB before thejoker301 took it over are great.

Does anyone sell those S1 lenses mounted in a holder?

 

[VirtueViolater]

I think the acrylic lenses work fine for lower power builds, seem to shape the beam ok. If I plan to use a build for burning, I use a better lens and more powerfull diode