Mitsubishi ML520G71...Red Holy Grail or Flashlight Fail ??

[steve-o]

Yeh the greens are now the problem.. Multi-watt 808 diodes are now fairly cheap, just got to find large vanadate/KTP crystals pre-assembled, add lenses, and there we go :] Easy-cheezy lol.

[dave]

I think driving a 500mw diode to double of its rated CW figure would be termed as over driving the crap out of it! Don't you?

yea i was surprised to hear dave thought pushing the 300mw diodes to do 500mw was over driving the crap out of them.
I cant wait to get the 500mw diodes in a quad setup like i posted then. i think i will also do the same for a quad blue.
Just thinking of it makes me so excited to have a 3 to 4W red and a 3.5W 445nm just need to find a good source for a 2W green.
It will be one strong projector.
I will have to turn the power way down when i use it indoors.

[kiyoukan]

Well in our projectors they are not run CW.
So driving them like we do is not that bad, also take a look at what we do to the 445nm diodes.
We drive them just as hard and they last a long time with few problems.

[dave]

True, they are not run at cw in projectors, but the duty cycle using using Pangolin is way higher than 50%

[kiyoukan]

yes its higher than 50%
But with proper cooling with TEC's there will be no temp build up and keep the diode very happy.
I dont think driving them at that is to bad but only time will tell.
the price is good enough to push them even if it is a bit.
Seeing as for so long red has been behind it is finally good to now be lacking on green.
For the 500mw diode what would you push them to in your projector?
The 300mw diodes are proving very stable at around 750ma current and they give out between 500 and 625mw of power.
I would think with the slightly wider emitter and 2 wires from each pin to the emitter and it being open can should be able to get around 1W.
I now have an open can 300mw diode and am going to see how it does with higher current.
Again tho time will tell how long it lasts but lets hope they are like the 445nm diodes.

[CDBEAM]

Gentlemen.....stop and think about it.....all of us...in the " Laser Hobby " area....have really moved our hobby forward......many, many have contributed. And...we will continue to progress !!! Things have changed....in a fundamental way in our hobby.

No longer must we buy our blue lasers…we make our own….if we overdrive the LD...and it goes COD….put in a new diode(s)…..and dial it down some !!!The Cost/mW/Risk balance is greatly improved. Life is good.
Now….Red is very close to joining the ranks of blue !!! A huge thanx to all who have contributed ….and continue to forge ahead. When red is conquered….we will tackle green…..either with DI….or by some other method !!

One goal is to continue to drive the cost of the hobby down…..the more reasonable….the more may participative in our hobby….as I say….The Quantum Well is deep…Photons for all !!!! Another goal is to share our knowledge, experimental results….and overall enjoyment in each other’s success….and learn from others …”unsuccessful experiments “. In a way….our aggregate efforts….are a lab….and what we lack in efficiency….is compensated by enthusiasm !!

Please …continue to travel and evolve within our little corner….as like minded individuals….from ALL around the world join in !!! Thank you ! BEAM

[edison]

You can argu about overdriving them or not but one thing is for sure, if i sell a quad 637nm single mode diode module with lets say 900mw about 99% of my customers ask how many diodes is use. If i say 4 the second question is, are you overdiving them? So in my point of few you can,t over drive them unless the customer knows about it and get the garantee that the diodes will be replaced when they died. If i would take the risk of selling overdriven modules then i would loose money before i even start with 637,s. The replacement of the diodes would cost me a fortune and also i would loose good customers that rely on good quality modules. Modules are like tools, that,s why a carpenter buys and expencive makita because it never fails. That is how you should look to a projector. Its a tool that laserist need to do a show. So overdriving diodes is not really a good idea.But as a hobbyist you can get away with that if you want to stay a hobbyist. As soon you doing payed shows you need reliable equipment.

But nevertheless kiyoukan i,m very impressed how you found a way to collimate the diodes. I,m still not sure if its useable for graphics. I would like to have the cilindrical telescope to play with so when doing a groupbuy count me in. I have 4 dave lenses so hopefully there will be a groupbuy soon.

[steve-o]

CD- well said :]
Edison- I completely agree with if your selling modules to customers you want them to be as reliable as possible. Warranty repairs and company reputation is not something to take lightly with a business.
For experimenters such as some of us, though, over-driving these diodes (such as is done with the 445s) could be beneficial if a mttf (life-test) was established at different current levels. However, this data would be valid only if the manufacturer were to never change the manufacturing processes for these diodes for a specified time-period, and they sent an ECN to all of us if they were changed (which ain't gonna happen )
My point being: Overdriving is good for R&D; e.g. finding the acceptible operating limits of this LD, and if you're prepared for acceptible losses. Overdriving is not good (as Edison stated) for important shows and finished sold products.

[CDBEAM]

...This question will likely ramble on....almost like the " Tube vs.Solid State " debate that has continued for the last 60+ years in the audiophile community !!! See the attached array.....yes....it is a gross over simplification.....but....it starts to put the many variables into some order for consideration. Anyone....and there are many....with at least an order of magnitude more knowledge on LD properties than I....please make suggestions to modify this chart !!

It is a complicated issue....and the main watershed is " Hobbist " vs " Professional "...Thanx....BEAM

[Solarfire]

yes much closer.
It takes some time to setup to make sure every thing is perfect.
You can chose where to knife edge you could go for a larger part to lessen the dust problem.
yes dust is the enemy of this setup.
That why its going to be covered in an enclosure.
More details and pics to come this week or next now that i can work.

Have you actually tried this? I don’t want to sound pessimistic, but no matter where in the beam path you double the beam width via knife edging, the beam will be twice as wide. For example, if a cylinder lens magnifies a 1 micron focal point to 4mm then it will magnify a 2 micron focal point to 8mm. Not to mention Simons point, which is also a reason for using the Plano concave/Plano convex combination instead, also keeps aberrations down due to the smaller angle of incidence on the lens.