Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Laser Pointer Store

New 1.2w 638 diode CHECk IT OUT!

CaliKirk

New member
Joined
Mar 30, 2016
Messages
376
Likes
108
Points
0
Yeah I had the hopes up on the title as id love to see more red, but it's still promising that new 638s are still coming out. I'd be a happy man if I could have a 2w+ 638! Really, who wouldn't be?
 

Atomicrox

Well-known member
Joined
Jun 22, 2011
Messages
2,431
Likes
321
Points
83
+rep for that great comparison picture. It would be *really* cool to have one of these with most of the diodes available to us!
 

Alaskan

Well-known member
Joined
Jan 29, 2014
Messages
10,570
Likes
1,609
Points
113
I went and looked at the specs for the diode before reading the thread, with the power output curve vs temperature being fairly narrow, I was thinking it could not be pushed as hard as other diodes which can safely be run at higher temperatures, thus unable to get much more power out of it than the published rating. Then I thought about the wavelength, typically, the longer the wavelength, the higher the divergence and combining long wavelength with multimode and you get the worst of the worst in regards to mRad for the size of the emitter.

The divergence and beam shape of this diode would be acceptable if you used corrective optics and expanded the beam out to one inch diameter or more, but one inch/25 mm minimum for what I like to see. I love fat beams but the wider they are the more power you need to see them well, and red being a long wavelength our eyes are not as sensitive to that color requiring even more power to make an awesome looking beam. PBS combine two of these diodes, use a 30mm collimating lens and then you might have a decent fat beam pointer project using these, even without corrective optics if doing that with a + shaped output.

The output would be closer to a classic laser beam shape if using a 90 degree wave plate rotator to be able to put the rectangle shaped beams one on top of the other and then using corrective optics to expand the narrow axis to produce more of a square shaped beam. Here is a cropped photo from Opt Lasers RGB laser showing just the red diode section where he combines the output of two red diodes for more 638nm power, you can see the round wave plate rotator in front of the right most diode output. Do something like this with a PBS cube with corrective optics and you would have a nice beam, but to achieve lower divergence this method would require adding an expander after the negative cylinder lens and collimator pair you see on the lower left side of the photo (corrective optics so the fast and slow axis match closer).

Unfortunately, with all these optics the output would not be double, maybe 30 percent higher than a single diode, but nice beam. Because of that, if I were to build it I'd just use a big PBS cube and shoot the uncollimated output of the diodes through it at 90 degrees to one another (of course, due to being a polarized beam splitter, in this case when used in the opposite direction as a coaxial beam combiner) and then use a big 30+mm diameter PCX lens to collimate the beam and let the output be a cross + so as not to suffer the added loss. Opt lasers used the rotator and corrective optics because the beam needed to be more rounded for use in a projector.



I guess if you don't rotate the polarity of one of the diodes to allow the two rectangle shapes to exactly land on top of one another in the same plane by rotating one of the diodes to do so (first shooting one of the two diode outputs through wave plate rotator so although opposite polarities, the same shape landing in the same axial plane) then to me it isn't really a coaxial combiner, but a crossed polarity combiner due to the rectangle shaped outputs being 90 degrees from one another. That is the way I see it, but I believe in the laser optics world they still call it coaxial combining.

I've taken the time to go through how this works for the newbies, although fairly simple it took me a long time to catch on to what is happening with something like this.
 
Last edited:

Encap

Well-known member
Joined
May 14, 2011
Messages
4,672
Likes
1,485
Points
113
Then I thought about the wavelength, typically, the longer the wavelength, the higher the divergence and combining long wavelength with multimode and you get the worst of the worst in regards to mRad for the size of the emitter.

The divergence and beam shape of this diode would be acceptable if you used corrective optics and expanded the beam out to one inch diameter or more, but one inch/25 mm minimum for what I like to see. I love fat beams but the wider they are the more power you need to see them well, and red being a long wavelength our eyes are not as sensitive to that color requiring even more power to make an awesome looking beam. PBS combine two of these diodes, use a 30mm collimating lens and then you might have a decent fat beam pointer project using these, even without corrective optics if doing that with a + shaped output.

I've taken the time to go through how this works for the newbies, although fairly simple it took me a long time to catch on to what is happening with something like this.
Hey Alaskan---you're an optics and divergence enthusiast/specialist ---check out post #18 in this thread here for something I am pretty sure you have never encountered but is way out there X-files cool--- See #18 of thread:http://laserpointerforums.com/f44/world-first-high-power-underwater-handheld-laser-98630-2.html

"The optical properties of water can be manipulated with very intense laser light to act like a focusing lens, allowing nonlinear self-focusing to take place. At the same time slightly different laser wavelengths travel at different speeds in water due to group velocity dispersion and can be arranged so that a laser pulse also compresses in time as it travels through water, further concentrating the light"
 
Last edited:

badboybilly

Well-known member
Joined
Mar 5, 2015
Messages
1,325
Likes
522
Points
113
Hey Podo
I just saw your NUBM47 A1 laser on utube hitting 8.8w, old video but I'm curious what current you had it set to, was it a freak diode, did you just take it out of the freezer before the LPM test, I have 2 A1s set at 5a and both average 7.2w!
 

Alaskan

Well-known member
Joined
Jan 29, 2014
Messages
10,570
Likes
1,609
Points
113
E ncap, responded in the water thread, interesting stuff, now I'm wondering what cool stuff could be done with a water lens of some type.
 

Podo

Well-known member
Joined
Nov 7, 2013
Messages
652
Likes
277
Points
63
Hey Podo
I just saw your NUBM47 A1 laser on utube hitting 8.8w, old video but I'm curious what current you had it set to, was it a freak diode, did you just take it out of the freezer before the LPM test, I have 2 A1s set at 5a and both average 7.2w!
Yes, I put the laser into freezer first and there is actually a ice pack cooling it when I did the test to see how strong the diode can go with such setting.
 
Last edited:

Alaskan

Well-known member
Joined
Jan 29, 2014
Messages
10,570
Likes
1,609
Points
113
What happened with the G84 tri-beam 638nm laser diodes, were they just a limited run, I don't see them on eBay anymore.
 
Joined
Feb 12, 2016
Messages
339
Likes
138
Points
43
Hi Podo,

I wanted to start a new thread but maybe to revive this one is not a bad idea...
I saw you have a good colection of red LDs to compare.
Did you accidentaly have a chance to check out this one - I found it on goldenstarlaser page:

RED 638 2500mw

Seeing that the name ends with G84 it might be a chinese version of Mitsu 3-beam diode or maybe something completely new?
Not cheap anyway and min 10 pieces to buy...
 
Joined
Feb 12, 2016
Messages
339
Likes
138
Points
43
Mitsubishi Tri-beam has code ML562G84,
this one JLD6325ZA-G84.

Why do you think it is the same, do the LD codes mean nothing?

Yes, they both end with G84 (this is why my question) but rest of signs are different.
 




Top