Prisms for 445nm diode front surface knife edging

[lasertack]

@solarfire

Hi,

10 blue you can get immediately, for the 10 red please post your needs in the thread for GB for red prisms and chose the size. LINK

Alex

[planters]

Ditto Solarfire...
Pending the pics of course.

The size is an important issue. The typical 445 stripe is 4.5 mm high and if perfectly placed on these 5mm prisms there is only 250um each side to play with; workable, but tough. 10mm may mean a significant increase in glass and cost, but I do not see a jump when buying cubes (two prisms) at these two sizes. and 10mm would mate well with the typical Fexmount type of support. Somewhere between 5mm and 10mm might be optimal.

[lasertack]

Ditto Solarfire...
Pending the pics of course.

The size is an important issue. The typical 445 stripe is 4.5 mm high and if perfectly placed on these 5mm prisms there is only 250um each side to play with; workable, but tough. 10mm may mean a significant increase in glass and cost, but I do not see a jump when buying cubes (two prisms) at these two sizes. and 10mm would mate well with the typical Fexmount type of support. Somewhere between 5mm and 10mm might be optimal.

@planters

the 5mm prisms are intersting when aspheric collimators are used for 445nm. For single mode red diodes you can use them as well. If you use O-Like´s for 445nm diodes then you may need larger prisms or you deal with the a little bit of lost power.
I think there should be 5mm or 7mm cubes available out there.
If you think about different mount sizes, think about this point as well, tighter stacked beam is not the only goal by using this prisms. You also can use smaller mounts like kvant, laserwave... do this and just only one large mount for the pbs. The size of your module will be reduced even if you use one larger mount for the pbs. BTW, you can use a small mount for a 10mm pbs as well.

Regards

Alex

[planters]

Alex,
Alas, I am using the O-like collimators and a source of 7mm prisms would be helpful. For the reds, the multi-mode G71s are exciting and even though the optimal collimator appears to produce a 2mm high beam I believe a 7mm size might be optimal in that it is still quite small yet gives 40% more edge to work with. I like your link to a GB with a vote. That might be the best path.

Eric

[dsli_jon]

One important issue, however is whether the edge of the prism is chamfered. ..Can we see a similar micrograph

Don't think we really need the macro-shots for that... lookie a li'l closer..



..yes, the macro-shots will help show-up edge quality - which, yes, is important, but a different 'issue' vs a chamfered-edge (..as opposed-to a razor-sharp edge..) Still, looks-like even Kv uses at-least somewhat chamf'd prisms -



.. so, perhaps it will not prove to be that much of an issue.. in any case, we should-see some efficiency-gains over mirror-edging.. whether these will prove to be yet another 'game-changer', is TBD, but... at least these prices are making it 'reasonable' to-explore...

@ Alex - just-curious if you've actually built these into a multi-watt knifed-rig, and, if-so, what kind of efficiency did you see vs mirrs? Yes, it's understood that 'choice of lens, diode-current', etc, etc are all 'factors', but even so, it would be easy to say, set-up a rig with, say, 4x diodes, each putting out 1.2W of 445, post-lens, and off a 4-up knifed mirror-rig, you got "X", when-summed (..this also assumes that, yes, you are an ace at knifing.. ...And again, same test-conditions, only using these prisms, and you got "Y", when summed... something like that.. ..Any real-world 'case-study' data like that?

..Not trying to appear 'critical' or anything, but, ya know.. these are the sorts of questions potential-buyers of 50-60 pieces of practically-anything, tend to ask.. And, while this sort of 'minutia' may-not be too 'relevant' for those building 2-4- ..maybe even 6-bangers, for those doing 10+ up's... 'chamfered vs un-chamf'd' is at the very-least, something you wanna know, going-in..


cheers..
j

[planters]

Jon,

I agree with your point. We need to know. And a micrograph will show this, chamfer and edge. The angle of the chamfer is important. If parallel to one of the faces then unless you are coming in with a SERIOUSLY divergent beam then this should stay out of the way. If it angles outward then we got a problem. Those images you posted do not magnify well enough for me to see what is happening. But I think Alex could use a simple lens and tell with even low magnification if the angle looks good. Right?

[lasertack]

Hi guys!

Here is the reflectance curve.

[lasertack]

As you can see the losses are 0,12572% @ 445nm (nearly 0).

[lasertack]

@planters

Ok, I will do it now.

[lasertack]

@planters

I used a lens with high magnification and could see the the edges are a little bit rounded, no chance to see with your eyes without magnification. Unfortunately I cannot upload this large picture to PL (it fails without any notice). By reducing the size the quality gets worse and you wont see anything. So I uploaded it on Rapidshare LINK
But I think we should to wait for Daniel´s pictures which will be taken with a microscope. Kvant´s prisms seem to be rounded as well. I think the reason is to protect the edges from breaking off.