collimation of the 445nm diode?

Joe Farina · Post by **Joe Farina** » Tue Jun 15, 2010 10:38 am

After seeing the output beam from the 445nm diode, I wonder how it could be collimated. It looks like the beam is elongated by a factor of about 8 or more. I have done this with a dpss beam that was elongated by a factor of about 3 or 4, with two cylindrical lenses in a good Melles Griot mount which was designed for the purpose (I got this as a freebie when I bought a Melles Griot blue dpss laser). The options seem to be either cylindrical lenses or anamorphic prisms. My guess is that the cylindrical lenses are a better choice, if someone has an appropriate mounting device for them. If not, then anamorphic prisms might be easier (?). But I've never used them.

Jem · Post by **Jem** » Tue Jun 15, 2010 10:45 am

Hi Joe

Take a look here...

http://www.photonlexicon.com/forums/for ... y.php?f=51

There are plenty of folks there who are trying to tame the beam(s) from these diodes.

Cheers

Jem

Joe Farina · Post by **Joe Farina** » Tue Jun 15, 2010 11:13 am

Thanks, Jem, I definitely want to follow those discussions. It looks like they are quickly making good progress.

Jem · Post by **Jem** » Tue Jun 15, 2010 11:23 am

Yep, there are some clever folks over on PL i'm sure they will have an elegant solution shortly

dave battin · Post by **dave battin** » Tue Jun 15, 2010 11:58 am

yes i too have been watching these guys

when i get up the nerve to hack into this nice piece of equipment(casio projector), i plan on trying the B&W optical train to see what happens, its two collimating lenses sit on either side of the prisim pair .................

wler · Post by **wler** » Tue Jun 15, 2010 7:32 pm

Joe Farina wrote:The options seem to be either cylindrical lenses or anamorphic prisms. My guess is that the cylindrical lenses are a better choice, if someone has an appropriate mounting device for them. If not, then anamorphic prisms might be easier (?). But I've never used them.

I think the prisms are easier to use. In fact I was pondering about a group buy for such prisms, which are usually quite expensive, and got a good offer for this. But I am not so keen getting into the kind of trouble dealing with this, and at any rate I first like to make some more detailed (simulated and hardware) tests to see what precisely is needed. One of the points is to get as much light through a spatial filter; the problem being that the beam can never be focused on an area that would be smaller than the aperture of the diode. I guess the problem is similar to coupling a diode to a fiber and it seems that the efficiency is typically low.

I believe that the the width-to-length ratios apparent in the pictures in these forums are somewhat mislaeading, and that a magnification ratio of like 4 is appropriate; but let's see!

-Wolfgang