Potential resolution

[Spelljammer]

I don't like the pinhole idea because it limits the light that passes through, substantially. And 20 mW is barely enough for decent speed prints. I prefer the lens approach. This one on ebay has a focusable lens. At least this way you get the full 20 mW instead of about 3 mW through a pinhole.

http://www.ebay.co.uk/itm/405nm-20mw...item58ae5e9eed

[Anuvin]

The laser is focusable. It looks just like the one you posted. It doesn't focus enough.

Also, as the print level moves, wouldn't you need to refocus?

[Spelljammer]

Anuvin, sorry, all this talk of pinholes in foil led me to believe that the laser wasn't able to focus without it. You are right that there is a need to refocus with layer height. Although, it seems good for an inch or two. And moving faster over a given spot, but hitting it more often (so that it can still cure) has the effect of tightening the focus...but there are limits. This brings us back to the floating laser idea...

[Feign]

The floating laser base, hydraulic build platform, and floating build resevoir (my favorite of the three) all give the Peachy a fixed focal point. If we're getting to the point of microstructures though, lensing turns out to be absolutely essential. I did a quick browse through Wikipedia about diffraction and found that (according to the papers linked on the first page) while reflective diffraction needs structures to be in the order of 10x the wavelength of the light you want to exhibit as the viewed color, aperture diffraction becomes a problem at the aperture being below about 6-7x the wavelength of light passing through it. The problem becomes not one of lase size, but of how much resin is partially cured by light scattering and refracting within the resin itself. In the macroscopic scale, this has no effect on a hard ridge, but microscopically, it would cause any corners you make to be deeply rounded off by partially cured resin.

Granted, having a microtexture of gently rounded divots might also have interesting optical effects, just not the deeply iridescent coloration of sharply etched silicon.

[chipphydes]

I brought this up because the low-end lasers have horrible "spot" size and shapes. At least a camera pinhole lens with a given aperture size you can get an idea of the resolution possible. When I get my Peachy Printer, I plan to replace the laser with a circular focus laser diode module. Very high cost but I will know exactly what the spot size is. Ultra fine resolution is my goal.

I do like the floating lens approach as it should be adaptable to any light source (some modifications, of course).

[chipphydes]

Has anyone thought of using singlemode fiber optic cable as a way of cleaning up the laser output? Not only is the diameter of a single strand the diameter of a human hair, the cable is flexible and very energy efficient. With sufficient length, the laser could be firmly mounted to one end and the other end could be attached to the floating laser base.

[Anuvin]

@Spelljammer - You know I love that floating laser design. Honestly, the hardest part of the floating laser? Finding a container with perfectly straight sides! So far, I have 2 part baseball card boxes and aquariums. Let me know if you find any good containers to use for a floating laser.

@Feign - I am hoping we can put some of your research into practice soon. I have no idea if we will be able to really get the laser that perfect. Lots to deal with - Mirrors, aperture, focus, and probably lots more. All problems we can overcome, but it will be a hard fight. Can't wait for everyone to have one so we can get ideas like this rolling.

@Chipphydes - I like the way that laser diode sounds. Got a link on that? An optic cable would be great, that is a fantastic idea! Isn't it also kind of expensive, and tough to ship? Perhaps that will be an option for Pro backers and as a DIY hack, maybe an add-on. No matter what happens, that is an idea worth investigating, for sure. Got any more insight on lasers for us?

[chipphydes]

Anuvin

Try this for laser diodes http://www.digikey.com/product-searc...-diodes/524333

Try this for singlemode fiber cable http://www.l-com.com/fiber-optic-bul...on-style-cable

I look at something like this for a DIY hack or on a Peachy Printer Pro. However, if it works well and is cheap enough it could be adapted now. Just a thought.

We need an experienced optical engineer in on this thread to come up with something that can be used at a price we could all afford or tell us we are barking up the wrong tree.
.

[Feign]

Chipphydes, from what I understand, the resin needs UV light to cure. Specifically in the 300nm-350nm wavelength. The laser diodes you've provided aren't in that small a wavelength.

It's kind of part of the reason so many people were thinking that the Peachy couldn't possibly be under $100. Where the Peachy team is getting UV lasers for an affordable price is kind of a mystery. Likewise, most kinds of glass are pretty good at blocking UV rays, Coming up with focusing lenses that will work well for the Peachy might be harder than we expect. Hence the pinhole attenuator rather than a compound lens.

Thankfully, UV photography is a thing, so there are whole forums that have talks about what camera lens sets are permissive to UV light. Somehow I doubt there is much info on fiber optic cable in the same vein.

[Morten]

Love where this thread is heading, lots of interesting info and ideas!

Another way is to use a beamsplitter, maybe? My soundcard has 5.1 channels, enough to control 4 mirrors. Perhaps split the beam into one larger and one very tightly focused beam, you could create a "Pheachy Hydra" and use the small beam for surface details and the large one for volume curing.