That's not correct, I can adjust the beam so it neither converges or diverges and is wide to converging at 50 feet and past that to converging at 1 foot and then the beam spreading out again, And everything in between, That's because I'm using 18X Cylindrical Lens on the large divergence Fast Axis Which is a 6X plus a 3X Cylindrical Lens together........Can you take that laser pointer and adjust it so when beaming out into the night sky the beam is adjusted so it neither converges or diverges, as strait a line as you can adjust it to be? That would be infinity focus. As it is, I believe the beam is focused to converge to a point 50 feet away, beyond that the beam spreading out again.
Since the NUBM44 has such a large divergence, unless expanded to close to 3 inches diameter, you can try to adjust it all night long and will never get it to stop diverging into a fan at the end of the beam, but once set to infinity focus, the beam is as tight as you can make it without being focused down to a point in space before crossing over to spread out again.
Yes I know that, I only added the mRad cal because it was my latest one, that's all......Now to get Acc. to understand he is focused to a point and that doing so has nothing to do with mRad when at infinity
Brother Acc., not meaning to talk down, but I don't think you are catching on to the idea yet, mRad for laser pointers only applies to a beam which has been collimated to "infinity" focus, not what you are doing. I suppose you could say your laser is not diverging, or specify an amount of beam divergence when hitting a target 50 feet away and in a different way be correct, but the mRad figure we use with laser pointers is in regard to the optical divergence when set to infinity focus which is as close as you can get to neither converging, or diverging. Only thing left then is the divergence caused by the relationship of the size of the "point" source to the amount the beam has been expanded and then collimated.
That's not correct, I can adjust the beam so it neither converges or diverges and is wide to converging at 50 feet and past that to converging at 1 foot and then the beam spreading out again....
I was just using what Alaskan had said, By "neither converges nor diverges" what I really mean is the beam is slowly diverges BUT you can't really tell because it just looks like a nice straight parallel beam going up into the night sky.....You might need to clarify...
You can't have a laser beam that neither converges nor diverges, as that would require a divergence of 0°, which is physically not possible.
18X Cylindrical Three Lens Fast Axis Correction is how, The beam at the last lens is 4mm x 8mm and at 50 feet the beam dot is 8mm x 16mm........I still don't understand how Acc. is getting such a low divergence with such a small aperture when using the NUBM44, expansion is expansion whether one or both axis, the same thing. Surely the pointer must be focused to that small of a spot instead of at infinity, if so, you cannot use the spot size to calculate divergence. To get under 1 mRad would require a lens which is close to 2.75 inches diameter with that diode. IDK, maybe larger, what is the divergence using a 6 mm diameter collimating lens, 11 mRad?
I don't know about all of that, All I did was put the numbers from my measurements into the mRad calculator and pressed the calculate button......Yea, I was trying to explain neither converges or diverges, except for the unavoidable divergence of the beam due to the size of the point source (not really a point source) and the amount of expansion. The way I calculate the total beam expansion is based on the mRad you would get from a 6 mm "G2" lens. For example, if you had 10 mRad with a beam 4 mm wide, no matter how you cut it, to get 1 mRad, the beam would need to be 40 mm wide.
Yes, I know that, That's why I said "just looks like a nice straight parallel beam going up into the night sky", Like you said it just "looks" as if.....Even though the beam looks like it is straight and not diverging as it goes up into the night sky, you really can't see the divergence because as the distance of the beam increases from your eyes, it is also becoming larger in diameter, but being farther away looks smaller to you. So, if you saw the beam's diameter at 5000 feet, it might be 5 meters across, but would still look the same to you as your perspective hasn't changed. You would need to be at the 5000 foot mark of the beam to see its actual diameter.