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



New! Sharp Diodes 1W 520nm & 5W 455nm & +2W 638nm

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
I was able to focus to a good tight point with my 25mm bi convex, I'm just saying the beam was not square after the 25mm lens, it tapered down to a tiny - which is interesting, the diverging raw output stays square until my lens, but after a lens it focus down to a - bar..........it's interesting to think about how the piece of fiber they used is interacting with the raw output, is it the distance across the width of the cyl fiber that's acting as a lens pair ?




@ Lifetime17 : Have you seen these, I am tempted to get one but 120.00 is a bit high.
 
Last edited:



Singlemode Laser

Well-known member
Joined
Jun 25, 2017
Messages
322
Points
63
With multimode laser diodes it is physically impossible to get the same beam diameter for both axes and the same beam divergence at the same time.

Singlemode
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
Could we find a FAC that would get us as close as the c-lens pairs we use or is it not possible given the physics ?
 

logsquared

Active member
Joined
Dec 9, 2011
Messages
217
Points
28
I was able to focus to a good tight point with my 25mm bi convex, I'm just saying the beam was not square after the 25mm lens, it tapered down to a tiny - which is interesting, the diverging raw output stays square until my lens, but after a lens it focus down to a - bar..........it's interesting to think about how the piece of fiber they used is interacting with the raw output, is it the distance across the width of the cyl fiber that's acting as a lens pair ?
Sorry i misunderstood your results with the 25mm. Sounds promising then. You have a longer fl lens to try?

I found this pic online that shows a cross section what is happening in the fiber.
balllens.gif

Those phosphor things look really cool. I would buy one but my laser budget is zero at the moment.
 

CDBEAM777

Well-known member
Joined
Feb 25, 2010
Messages
1,464
Points
113
I assure you all....THIS FAC development has my hair on fire !!!. I had dreams of a simple alternative to C-Lenses....Well....Sigh.....Not so quick !!!!!

The Green FAC is OK with a 3E....1.25 mRad.....could be better. Divergence is comparable to DPSS divergence.....BUT....the 525 nm line is strong competition for a 532 DPSS....in colour ( Read Perceived brightness ) !!!!….and a Direct diode is surly preferable to all the complexity and stability issues of a DPSS !!

The Blue FAC…...Sadly....must start out with larger die....so.... This one CAN be tamed....to have about 1.25 mRad …..with a set of 6X C-Lenses....BUT....a NUBM044 + G8 + 6X C-lenses can also be tamed....just as well....if not better....not sure yet.....school is out !!!

AND....Concerning the RED FAC.....I have a sample....but have been focusing on the Green....now the Blue.....Red is likely equal to Blue in die geometry....but no info yet.....Later this week !!!

In conclusion...IMNSHO....The Green FAC is a Keeper.....The Blue and Red FAC....Well....NO MAGIC BULLET HERE !!! CRAP !!! I will continue to experiment. See pics.

CDBeam
 

Attachments

Last edited:

aaronnoraa

Active member
Joined
Jun 20, 2015
Messages
133
Points
28
I assure you all....THIS FAC development has my hair on fire !!!. I had dreams of a simple alternative to C-Lenses....Well....Sigh.....Not so quick !!!!!

The Green FAC is OK with a 3E....1.25 mRad.....could be better. Divergence is comparable to DPSS divergence.....BUT....the 525 nm line is strong competition for a 532 DPSS....in colour ( Read Perceived brightness ) !!!!….and a Direct diode is surly preferable to all the complexity and stability issues of a DPSS !!

The Blue FAC…...Sadly....must start out with larger die....so.... This one CAN be tamed....to have about 1.25 mRad …..with a set of 6X C-Lenses....BUT....a NUBM044 + G8 + 6X C-lenses can also be tamed....just as well....if not better....not sure yet.....school is out !!!

AND....Concerning the RED FAC.....I have a sample....but have been focusing on the Green....now the Blue.....Red is likely equal to Blue in die geometry....but no info yet.....Later this week !!!

In conclusion...IMNSHO....The Green FAC is a Keeper.....The Blue and Red FAC....Well....NO MAGIC BULLET HERE !!! CRAP !!! I will continue to experiment. See pics.

CDBeam
Hey CDBeam, did you try using a larger, non-threaded long focal length lens on the NUBM08 FAC? I'm curious if the issue is just that the beam isn't expanding enough before collimation.
 

Coonie

Active member
Joined
Jan 12, 2018
Messages
199
Points
28
Have any of you bought the linear fac diodes? I bought the 638 linear one. Maybe it will be better. I'll post once I get mine and test it out.
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
I assure you all....THIS FAC development has my hair on fire !!!. I had dreams of a simple alternative to C-Lenses....Well....Sigh.....Not so quick !!!!!

The Green FAC is OK with a 3E....1.25 mRad.....could be better. Divergence is comparable to DPSS divergence.....BUT....the 525 nm line is strong competition for a 532 DPSS....in colour ( Read Perceived brightness ) !!!!….and a Direct diode is surly preferable to all the complexity and stability issues of a DPSS !!

The Blue FAC…...Sadly....must start out with larger die....so.... This one CAN be tamed....to have about 1.25 mRad …..with a set of 6X C-Lenses....BUT....a NUBM044 + G8 + 6X C-lenses can also be tamed....just as well....if not better....not sure yet.....school is out !!!

AND....Concerning the RED FAC.....I have a sample....but have been focusing on the Green....now the Blue.....Red is likely equal to Blue in die geometry....but no info yet.....Later this week !!!

In conclusion...IMNSHO....The Green FAC is a Keeper.....The Blue and Red FAC....Well....NO MAGIC BULLET HERE !!! CRAP !!! I will continue to experiment. See pics.

CDBeam

So the nubm03 with FAC works well with a 3E lens producing a beam comparable to DPSS (((((( WOW )))))) That's awesome. I will have to get some. How about some beam pics ? :)
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,009
Points
113
Only thing is, the G8 also works well with a normal non-FAC NDG7475 producing a divergence comparable to DPSS too. The advantage of the NUGM03 is the wavelength is 525 nm which is closer to the peak sensitivity of our eyes than 520 nm.
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
I have 7475 with G8 and far field the spot is a wide bar/line
I do have a 505nm direct with a G3 that is comparable to dpss.

How much better are these FAC 03's than non FAC 03's ? Is the far field spot square or is it a line/bar ?
 

CDBEAM777

Well-known member
Joined
Feb 25, 2010
Messages
1,464
Points
113
I have 7475 with G8 and far field the spot is a wide bar/line
I do have a 505nm direct with a G3 that is comparable to dpss.

How much better are these FAC 03's than non FAC 03's ? Is the far field spot square or is it a line/bar ?
MMMmmmm ???? Define Far Field...is that 15M....or 150M....or other ??? My FF is 14M... IMNSHO...after that...to some degree...Parallax View presides. CDB
 

CDBEAM777

Well-known member
Joined
Feb 25, 2010
Messages
1,464
Points
113
Hey CDBeam, did you try using a larger, non-threaded long focal length lens on the NUBM08 FAC? I'm curious if the issue is just that the beam isn't expanding enough before collimation.
AA ...Will try this !!! Thanx !! I have just the lens in mind. CDB
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
Yea I don't like the long bar my 7475 w/G8 makes at hundreds of meters, with a G8 and 3XBE it's much improved but no more classis laser beam that way of course. I had planned to use a G2 and 4x c-lens pair to correct but have not done it, been very busy with another interest.
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,009
Points
113
From what I’m coming to see, FAC corrected diodes are not the answer for laser pointers, that their use is for two purposes; squaring the beam prior to a tight pin-point focus for more uniform burning and for IR pump diodes to better focus a more uniform beam into a DPSS crystal, otherwise not useful in pointers. Better to use cylinder pairs or a prism pair to square up the beam, correct?

Edit: Also, when expanding the slow axis of a laser diode by any method to square the appearance of the beam close in only increases the difference of the divergence between each axis, so in the great distance the beam pattern becomes more of a bar shape than before, is this not also true?
 
Last edited:

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,465
Points
113
I just don't see a single lens, even a fused silica plano aspheric cylindrical FAC or a Fiber FAC having the leverage of a c-lens pair set a distance apart, but I would love to be surprised.

If I knew enough about the lens geometry and the diodes junction dimensions and emission angles ( which are listed on the spec sheet ) then I could do the math and tell just what will do what, but even from a novice point of view I don't see one positive cyl. lens as having the leverage of a negative-positive cyl. lens pair set a distance apart........the only way would be if there was room to catch the narrow part of the beam as it exits the junction and square it with the slower diverging wide part of the beam right out of the junction...........there by producing a square beam with both axis diverging at the rate of the slow axis, but #1. I don't think there's room to do it and #2. how long will the beam hold it's shape given the leverage of one cyl. lens starting with such a wide junction with such aggressive fast axis divergence ?

As I understand it the FAC Fiber is acting like a bi-convex cyl. lens.

I know I'm not using all of the correct technical terms but that's how I see it, however I would love to be surprised.
 
Last edited:

Coonie

Active member
Joined
Jan 12, 2018
Messages
199
Points
28

"
FAC diodes need a Long Focal lenth lens to collimate the beam.

If you where to put a G-lens or use even like an Aixiz Lens on a diode that is FAC'ed you would get really bad divergence. You need a Long Focal length lens. "
 




Top