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Big Reds

styropyro

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Does anybody know of a good source of bigger red modules or diodes (Preferably 300mW+). I am in no way capable of buying an expensive laser right now but does anybody know why we don't ever see the bigger reds? I mean there are green lasers that go super high (i.e. Morepower's Class IV herc. which has an even BIGGER pump diode) but why don't we ever see huge reds?
 

Things

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i think it's because the can is so small, and would have to be bigger, well heatsinked, and good lenses, so i'l cost a bit.
 
S

SenKat

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Anything higher than about 250mw is a multi-mode diode...which means, HORRIBLE beam specs, etc...you CAN buy them in super high powers, but you need a few hundereds of dollars worth of lenses to make it look decent...
 

Gazoo

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SenKat said:
Anything higher than about 250mw is a multi-mode diode...which means, HORRIBLE beam specs, etc...you CAN buy them in super high powers, but you need a few hundereds of dollars worth of lenses to make it look decent...
Yeah, I saw the sony 500mw 9mm diode. Too bad it isn't single mode.
 

flogged

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What senkat said. Trying to find any red diodes over 250mW that are single mode is nearly impossible. For a pointer or a burning laser you really want a single mode diode. They make it easy to get tight collimated beam. Multimode or high power often amounts to a bunch of emitters in the same package. It's really impossible to easily join all the beams.

At high powers most lasers are DPSS. Turns out it's easier to make a powerful laser if you separate the pump from lasing assembly. It doesn't matter if you use a multimode diode or a diode array.. you still get a nice output beam. Basically a DPSS laser is the same as a flash-pumped laser (like a ruby laser) except it's much more efficient. With a diode laser the lasing cavity is constrained by the nature of the P/N junction, and also apparently it's hard to make high power single mode diodes. DVD diodes are about the best one can get. Ironically if a high power red isn't multimode it's likely DPSS.

My ideal red pointer would be around 100 mW @ 635 nm. The best single mode 635nm diodes I've found are around 40mW, and they are very expensive. Apparently they are hard to make. I'm not certain why all the 808nm pump diodes are so much cheaper - it's likely a combination of economy of scale, and just being easier to produce. I believe 635 nm(ish) diodes have to be under some sort of stress (cant remember if it's tensile or compressive) to get the higher frequency.
 

Daedal

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I have seen red go as high as 1W or even more, but they were DPSS 635mW... and for these get ready to shell out well over the price of the biggest Herc... :eek: :(

I think eventually things will start getting more and more reasonably priced when they become available in a much more stable fashion. I really can't believe that it took so much for reds to catch up like this, when BluRay is already up to about 200mW single-mode! It's kind of disappointing to be honest as I personally favor the red lasers over any other... :-[

Quick search found this... No clue on if it is in fact multimode :-?
http://www.sony.net/Products/SC-HP/laserdiodewld/products/pdf/sld1332v.pdf

--DDL
 

pseudonomen137

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Daedal said:
I have seen red go as high as 1W or even more, but they were DPSS 635mW... and for these get ready to shell out well over the price of the biggest Herc...  :eek: :(
--DDL
Actually I'm guessing the 1W 635nm you saw was not even DPSS but a multi-mode diode. Those run into the thousands though. The other alternative is 671nm DPSS but a watt of that is more expensive than a watt of green.

As everyone said above, the problem with strong diode lasers is that a structure that confines the output to a single mode cannot support more than a few hundred mWs if even that. Past that a multi-mode structure can bring 808nm diodes up to a few watts in a single emitter, but those are less coherent and thus result in FAR worse beam specs.

With a multi-mode diode you could spend all the money in the world on optics, and the beam specs would still likely lag 10x+ times worse than a single-mode diode or DPSS laser.

Therefore, and unfortunately, high power diode lasers aren't practical for much more than pumping crystals (yet?).
 

flogged

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So I did some poking around and made some interesting discoveries.

OpNext (Hitachi) is still actively working on high power single mode diodes. In just the past year they've come out with a bunch of new high power CW diodes in the 639-642 nm range. Highest power currently available is 90mW. These look like pimp diodes. See the spec sheet:
http://www.opnext.com/products/details/InfoIndustryLD.cfm
You'll have to scroll down to see the new products.

Also see this press release on the 90mW 642nm diode:
http://investor.opnext.com/releasedetail.cfm?ReleaseID=229263
(from the press release)
About the HL6366DG, HL6367DG and HL6378DG The Opnext HL6366DG, HL6367DG and HL6378DG offer the world's highest optical output power, 90mW in 640nm wavelength band. This achievement was accomplished through a new process which includes a new waveguide structure and optimized structure parameter. The active layer thickness and facet reflectivity, results in a lower level of power consumption and extended battery driven time. These products make it possible to meet new application field.
I found this link, where they are selling these diodes. I just fired of an email to them to check pricing. I'm afraid to ask.
http://www.photonic-products.com/products/laserdiodes_visible/hitachi_visible.html#hl6362mg

There are also QSI (Korean I believe) laser diodes. These are available in 10,20,40 and now 60mW. Around 640 nm.

These two places have them:
http://www.roithner-laser.com/qsi.html
http://www.rpmclasers.com/QSI/QAL 600-654.htm

I checked the prices on these diodes at Roithner. They aren't known for cheap prices, but I wanted to get some idea. As I imagined the cost remains very high. The 10 mW is around $20 (reasonable), 20 mW is $72.00, 40 mW is $216.00.. and the 60mW can is going for $441 !!

Unless you have connections or get these surplus (or in large quantity) the cost is just too high.

However I still think there would be a small market for red pointers based on these diodes.

Consider that nearly all high powered DVD diodes lase close to 660 nm. LED_Museum did a review of a pulsar and he measured it @ 660 nm. What this means is a diode @640nm is going to appear close to 3x as bright as one @660nm (at the same power level). So a 100mW part would appear as bright as a 300mW DVD diode. Not bad.

I also noticed Hitachi is still actively working on these, and they appear to be moving most of their high powered stock to the 630-640 nm range (YES!!!) - and these are single mode. Keep in mind that 635 nm laser rocks did not appear on the scene until the late 90's, it's been less than a decade that they've been common. Hopefully in few years the prices on these will come down to the point where pointers (HAHA, bad pun) using these new laser rocks will become practical.

Oh, and OpNext as some great documentation on laser diodes you might want to check out..

like,
(diode surge protection and damage mechanisms)
http://www.opnext.com/products/details/documents/E608001_SURGE.PDF

(general info of LDs)
http://www.opnext.com/products/details/documents/SEC01_E.PDF
 

flogged

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I actually got a response from OpNext (first link in my above post). The 80mW 640nm diodes (HL6378DGR1) are going for $180.00/each in quantities of less than 25. This is not as bad as I thought. I'm hoping someone out there (laserglow?) makes a few red pointers with these. I imagine there would be a small market, but I really don't know.
 

flogged

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Daedal said:
How about this?

http://www.rgblase.com/prod/FB671.htm

This is what I was referring to and I just bumped into it by mistake ;)

--DDL
Those are DPSS, so they should have decent beam quality.

Unfortunately 670nm is far down the response curve.. not the best for a pointer. For example 1 watt @ 670 nm would only appear about as bright as 150mW @ 635nm.

HOWEVER, these would probably be good for a full color scanner. The longer reds appear more saturated (it's a true red, unlike 640nm which is more pink) and when combined with a deep blue (440nm) will allow a much larger gamut to be displayed, especially compared to CRT. Unfortunately you need a lot more power at these wavelengths to get them really bright.
 

flogged

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Gazoo said:
The highest cw red diode I have been able to find that is made in a standard 5.6mm package is 150mw.

http://global.mitsubishielectric.com/news/news_releases/2007/mel0684.pdf

A sample is only $250.00 if anyone cares to order one.. ;D
Good find. Notice this is recent, from 2007. They are still actively working on these.

My only question is whether or not the diode is single mode. If so, score. If not, oh well. They describe it as a 'broad area' emitter, which often means multimode. For a pointer/burning laser it's got to be single mode.
 

Gazoo

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Yes I know. However in the press release they do state it can be used for laser show devices. Hopefully someone can weigh in on this. If it is single mode, it would be awesome.
 

Daedal

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Very interesting... $250 though! :eek: I think I'm better off running the diodes SenKat is selling now. I'd kill 15 diodes before I even get close to the price of one of these ones. I also run the ones from SenKat at about that much, and they should last me about a month each... so that's over a year of red for damn near nothing... lol ;D

Thanx SenKat :D
DDL
 

Gazoo

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Of course I agree with you and would not spend $250.00 for a diode. But it is a good sign of things to come. Imagine when we will be able to get these for the same price as SenKat's diodes. And considering they put out 150mw, they could easily be over driven to perhaps 250mw. For now I am sticking with SenKet's diodes, they literally kick butt...lol. There isn't anything else around for a better price :)
 




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