Aspheric collimators for red and blue laser diodes

[steve-o]

Well, the 445's have already been pretty well sorted out as far as I know. Will these work with a 635nm diode? I may be interested in one for experimentation after a certain GB is done if there are any funds left .. ahh, the money-pit hobby .. :/
Rochester is a good lens, I heard from an optical engineer at Thorlabs.

[Solarfire]

If you are getting those kind of losses from the O-Like lens then it probably isn’t coated for 445nm, O-Like has a lens for blue that only has a loss of ~ 7%, so much better than the >25% you are experiencing. I’m not aware of O-Like having a suitable broad band coated, so a comparison of these 2 lens types is not conclusive.

A more conclusive comparison would be with a 450-G-2 lens which is more in the same class (~2% loss) and still much cheaper even shipped from the US to the EU.

[lasertack]

@dsli_jon

Sure, you can get a lens which makes the beam 3x1 at the aperture but you´ll end up with a huge divergence. Aspheric lenses give you a divergence which is higher as standard O-Like lens. Thats nothing new. In most cases you need to use prsims for correction. The output beam is much tighter and can be stacked much better as with O-Like lenses. And by using corrections prisms, you´ll get nearly the same divergence as with O-Like´s but with much more power.

@steve-o

It also works with 635nm diodes, especially with the popular 300mW Mitsubishi. You´re right, Thorlabs offers this lens as well but the price is 75€ + 19% VAT.

@solarafire

Did you prove the losses of the O-Like lenses or is it a value which you were told by the seller? I did. I have two types of O-Like lenses, for red and blue. And yes, I´m sure that they are coated for 445nm. They aren´t broadband coated but it doesn´t matter. For tests with red diodes I took one with red coating and for blue test I took one with blue coating. But back to the losses. 7%??? How did you get this result? Did you measure it completely out of focus with the lens completely screwed into the housing?
I dont think that my comparisons isn´t conclusive, because for every given wavelength I used a lens with a coating for exactly this wavelength. I´m not the only person who measured this lenses and get the same results. If you only take care of the divergence without using prisms this lens might not be the right choice but if you need the most power of the diode you can get, you´ll need to use aspherical lenses. And by using correction prisms, you´ll get nearly the same divergence as with O-Like lenses but with much more power.
And last but not least. 405-G2 is cheaper than my lens? I only saw them for 50 bucks or more.

Regards

Alex

[Solarfire]

Did you prove the losses of the O-Like lenses or is it a value which you were told by the seller? I did. I have two types of O-Like lenses, for red and blue. And yes, I´m sure that they are coated for 445nm. They aren´t broadband coated but it doesn´t matter. For tests with red diodes I took one with red coating and for blue test I took one with blue coating. But back to the losses. 7%??? How did you get this result? Did you measure it completely out of focus with the lens completely screwed into the housing?
I dont think that my comparisons isn´t conclusive, because for every given wavelength I used a lens with a coating for exactly this wavelength. I´m not the only person who measured this lenses and get the same results. If you only take care of the divergence without using prisms this lens might not be the right choice but if you need the most power of the diode you can get, you´ll need to use aspherical lenses. And by using correction prisms, you´ll get nearly the same divergence as with O-Like lenses but with much more power.
And last but not least. 405-G2 is cheaper than my lens? I only saw them for 50 bucks or more.

Regards

Alex

Of course I did... see here http://www.photonlexicon.com/forums/...ion-correction
405-G-2 on ebay ~ 30$ by Laser4u

[lasertack]

Ok, thank you for the link. Nevertheless by using this lens and correction prisms, you´ll get nearly the same divergence as with O-Like lenses but a much higher output power.
Did you ever try a lens with the same specs I offer?

[Solarfire]

For the 445nm diodes I've settled in on the 405-G-2 lens in combination with cylinder correction for best beam specs @ 3.5mm x 3.5mm @ <0.8mrad.

[edison]

That is right with blue diodes my experiance is fl 4mm is perfect for blue diodes in combination with a prism pair of cilindrical lens set. For red diodes single mode the optima,s are supurb so i will stick with those. For 635nm i would go for dave his lenses with a cilindrical lens set of kiyoucan,s groupbuy.
But the A390,s work well for blue diodes and a prism pair also

[taggalucci]

Hmmm, did you say for red you used a red coating meaning the colour red (and likewise for blue)?

The coating should be an opposing colour to the diode you're using as otherwise you'll get losses from reflections off the wrong coating.

[lasertack]

No, the coating for red looks a bit blue and the coating for blue is a bit yellow.

[lasertack]

Do we really need to talk about the coating knowledge?