New build!! 1w 520nm with 0.13 mrad

[trinh hong phuoc]

Hi LPF,this is my first with 6x cylinder pair lens,thank you CDBeam ,he share to me 2 pair,
I use NDG7475 with g2 lens and driver from xwosse ,i set at 2,2A
Now, I have created a divergence small enough to enter space,
the divergence is 0,13 mrad,i will make a 10x beam expander to dow divergence
Here í some pics

 

[trinh hong phuoc]

 

[Lifetime17]

Hi T,
Great job on the corrected 520nm beam awesome job.

Rich

 

[steve001]

Hi LPF,this is my first with 6x cylinder pair lens

Nice job and good to see another laser made with low divergence in mind. However, it would be a good idea to show the size of the spot terminated on a known distance distant surface. Pointing it into space doesnt do that. It would be interesting to show comparison photos between your laser and a typical 520 nm laser demonstrating the optical differences if you have another typical 520 nm laser.

 

[Alaskan]

Be careful to make sure the beam is set to infinity focus when measuring how much it expands to determine divergence in mRad. We had one member here in the past focusing his spot very tightly in the distance and thought that was it's divergence, it wasn't, it was his beam converging due to being focused to a tight spot on his target and wasn't really set to infinity focus. He was measuring how wide the spot was and then trying to do divergence calculations based on that. The divergence calculations only work at infinity focus.

 

[trinh hong phuoc]

thank all,Rick,Sever and Alaskan

I will have a long-distance test on this laser, the beam has no convergence point on its path, so I believe I calculated it correctly, projecting them in the sky, I can feel the tiny beam
i will up result

Edit: I will calculate carefully

 

[RedCowboy]

Very nice. Good job.

 

[steve001]

thank all,Rick,Sever and Alaskan

I will have a long-distance test on this laser, the beam has no convergence point on its path, so I believe I calculated it correctly, projecting them in the sky, I can feel the tiny beam
i will up result

Edit: I will calculate carefully

A simple way to focus to infinity, achieve an infinite conjugate is by adjusting the beam on a distant surface at least 100 feet (30.48m) and thereby making as small of a spot as possible.

 

[paul1598419]

Very nicely done. Thanks for showing it.

 

[CDBEAM777]

HMMMM....YES....HAMMER THOSE PHOTONS....Bang, Bang, Bang.......Slam them into Submission !!!! Assume the Position.....you unruly Wave Particle's!!!....GET IN LINE.........And March....in lock step....Toward the Asymptote of Ultra Low Diverergence !!!! Yikes !!!! I Just get a thrill outa such a build !!!
Obviously....my " Bar " ....is LOW !! Beautiful Work THP !!!! CDBEAM

 

[Alaskan]

thank all,Rick,Sever and Alaskan

I will have a long-distance test on this laser, the beam has no convergence point on its path, so I believe I calculated it correctly, projecting them in the sky, I can feel the tiny beam
i will up result

Edit: I will calculate carefully

Very nice host, I don't have anything in the green wavelength with correction lenses to adjust the output to have more equal beam profile geometries like yours does.

Regarding the infinity adjustment, if you have an adjustable beam expander it is possible to focus your beam to a smaller point in the distance, but I don't know how far out it can focus down to a smaller point with that particular beam expander. Maybe after enough distance you can't, I assume all lenses are limited in that way no matter what their diameter, but I believe the larger the lens diameter the more range of focus. If anyone wants to set this strait please chime in, as all I am going by is what I believe I've seen, I don't have the math to back it up.

 

[trinh hong phuoc]

Dear Chris ,yes I understand that, so I should write the divergence corresponding to the distance
For example:0.1mrad at 100m
Thank you
edit:If I create a 10cm beam at 1km, the beam is not focused on that distance, will it be 50cm at 5km?

 

[trinh hong phuoc]

A simple way to focus to infinity, achieve an infinite conjugate is by adjusting the beam on a distant surface at least 100 feet (30.48m) and thereby making as small of a spot as possible.

I also thought like you, but what Chris said was true, I'm not sure if they could be close enough or not, but at 200m, they were 0.13 mrad.

 

[Alaskan]

At first take, that low of a figure hit me as too low for that diameter expander lens, with a 6 mm diameter collimation lens alone, that diode produces about 2.6 mRad which in my opinion isn’t good at all, as the beam turns into a wide rake 300 meters out and more at that amount of divergence. However, the 6x beam correction must be why you can achieve that low of a divergence.

However, thinking about this more you very well may have achieved that low of a divergence. Here is my thought process: If your beam has a divergence of 2.6 using a 6 mm collimation lens with roughly a 4 to 5 mm beam width diameter and you expand that diameter to 35 mm, as an example, that’s roughly a factor of 7 to 9x expansion. Take that 2.6 mRad figure and divide it by 9 and you get a divergence of roughly less than .3 mRad which really isn’t that far off from what you found, but since you expanded one axis of the beam prior to the Sanwu beam expander which for one axis, reduces the divergence below 2.6 before being expanded, I can now see you very well may be getting that low of a divergence figure.

Although there should be two different divergence figures, one for the fast axis and one for the slow axis, unless the beam correction C lenses perfectly correct the two to exactly match together, one side will have some amount of difference. I’ve yet to see anyone call out both figures for these direct to wavelength diodes, so for most if not all of our hobby laser pointers, it’s unlikely both sides are perfectly matched. Regardless of all of this, or if one side is slightly different, the divergence figure either way is awesome, good work. You have my address

 

[trinh hong phuoc]

My thinking is similar to you, so if want beam expander works well, fast axis and slow axis must have the same divergence , we can charge divergence of fast axis by focusing the g2 lens
Edit: i measured divergence for fast and slow axis at 200m is 0.4375 mrad and 0.3125 mrad
With 6x cylinder

 

[Alaskan]

Close enough, nice.