Aspheric collimators for red and blue laser diodes

[lasertack]

It would also be interesting to see this lens versus the 405-g-2 or even the optima 4mm for red
I think it is a more "relevant" comparison

i am really "jealous" of your equipment Alex, but i am also very happy with the effort you put in this, sharing your research with all of us, with pictures, explanations and all. thanks man!

I´d be glad to compare this lenses. Unfortunately I do not have any of these (Optima or 405-G-2). If somebody could send me both for testing, I´ll compare them.

[steve-o]

How would this lens compare with Dave's 2mm lens? Afaik his lens is the "unbeatable" one so far ..

[planters]

lasertack,

I have some of the optima 4mm and the 9x 0.5 mm barrels that will hold them and would be happy to send you a set.

SF,

You are correct regarding the semantics. The diode generates the divergence and the lens modifies the divergence.

About a year ago you posted your extensive comparisons of collimators for the 445 diode. I may be remembering this incorrectly, but I thought the O-like and the 405-G-2 were closer in their beam diameter x divergence product and the overwhelming advantage of the O-like was the cost. I have never understood the reason the nature of the expansion telescope, be it a prism or a cylinder pair has any influance on the final quality of the beam, but when these lenses were compared there seamed to be a significant difference. I am, at this point, not addressing the light loss issues that become significant at higher magnifications with the prisms, only the beam quality.

Do you happen to know the specs. for the 405 lens? It would be interesting to compare the lens design parameters along with a comparison of their beam profiles as soon as that can be done.

[Solarfire]

How would this lens compare with Dave's 2mm lens? Afaik his lens is the "unbeatable" one so far ..

Another case of apples and oranges, if you want to compare lenses to one another they have to be in the same data ballpark.

[planters]

Correct!

But while we're at it, if someone can get you one of Dave's lenses, I might be willing to get DTR to send you one of the G71 diodes to do a proper test of the pertinent red diode that these lenses would be used for.

[Solarfire]

You are correct regarding the semantics. The diode generates the divergence and the lens modifies the divergence.

About a year ago you posted your extensive comparisons of collimators for the 445 diode. I may be remembering this incorrectly, but I thought the O-like and the 405-G-2 were closer in their beam diameter x divergence product and the overwhelming advantage of the O-like was the cost. I have never understood the reason the nature of the expansion telescope, be it a prism or a cylinder pair has any influance on the final quality of the beam, but when these lenses were compared there seamed to be a significant difference. I am, at this point, not addressing the light loss issues that become significant at higher magnifications with the prisms, only the beam quality.

Do you happen to know the specs. for the 405 lens? It would be interesting to compare the lens design parameters along with a comparison of their beam profiles as soon as that can be done.

Roughly speaking for 445nm diodes:
The major difference between the O-Like and the 405-G-2 is the O-Like is a 8mm fl lens and will clip the beam on the FA giving a relatively clean beam but at the expense of a larger beam diameter (beam geometry) at the collimator aperture with higher losses and lower divergence. The O-Like can be easily corrected with an anamorphic prism pair due to the lower divergence after the collimator. The 405-G-2 has a 4mm fl an NA of ≈ 0.5 and therefore able to capture the entire beam with a smaller beam diameter at the collimator aperture but a higher divergence. The 405-G-2 needs a higher magnification for correction, therefor best corrected with cylinders which can be selected for the magnification needed. A prism pair is only good for a magnification of ≈ <2.5x with BK7, SF11 is out of the question due to the tremendous losses involved. The losses between prisms and cylinders, when the same materials and coatings are used, are about equal if the prisms are not set above Brewster’s angle.

[steve-o]

Another case of apples and oranges, if you want to compare lenses to one another they have to be in the same data ballpark.

I want to compare beams, not lenses.

[planters]

SF,

I agree with you on almost everything you have said and you have put it quite nicely. What I have been contending here is that despite the smaller fast axis beam dimension after the Rochester lens, lasertack has found a SMALLER far field dimension as well. This was not a simple trade off of near field dimension against far field dimension. This lens appears to be a win-win. Maybe the 405 lens also shows a net gain at both distances, but I do not remember seeing this and that is interesting me.

Steve,

I agree, but you agree that we probably should do both. We will compare the beams from a single diode and by that we will compare the effects of these lenses.
I'm thinking that if we see that a certain aspect of the lens design such as let's say the variation of FL for the aspheres produces a trend, like shorter is better or longer is better then we might go further and spec a lens that we can expect will improve things even more.

[steve-o]

Ah, ok , point taken. Scientific methodolgy. nice.

[lasertack]

The beam profiler I used to analyze the lenses is now up for sale. Here is the LINK
I´m also selling a camera based beam profiler. LINK