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12.04.2015

Holocraft - Process for Fabricating Specular Holograms


The clearest video of a Matthew Brand hologram on the web.

It would seem that my blog is getting a bit more traffic now due to my previous post about my adventures with specular holography. I decided that it would be prudent to offer up my holograms in a crowdfunded fashion. I just launched a relatively modest campaign for $5000, which would fund a low-end CNC machine, aluminum stock, and a few months rent on a little tiny office/studio space where I can setup the machine and 'get my hologram on'.



'Holocraft', a program that generates toolpaths for a hologram's fabrication.

Originally, when I set out to do this project, my plan was to refine the cardstock holograms to a viable product that could eventually fund a CNC machine for creating high quality metal plate holograms, but the cardstock holograms are just not quite "there". The cost/benefit for getting them to look pristine is just not a viable route. But, I am sure someone would like to have them just as a novelty item, or maybe even to frame and hang on their wall. I am just not comfortable directly marketing them as a finished product, because I personally wouldn't want one myself. I want a heavy duty super duper shiny metal hologram!

I ask that if you think this project is cool, and want to see more stuff happen, please spread the word about it and tell your friends. Facebook, Tweet, and otherwise social-network the snot out of this blog and/or my Indiegogo campaign. I have this strong feeling that this medium is the tip of the iceberg, and that a lot of energy will change form as a result of it. It just needs to get out there in front of people and on their mind.

I've already figure out virtually everything there is to figure out about how to run Holocraft output on the CNC machine, what cutting tools to experiment with, what grade aluminum I should use, and have already sourced every single thing that I will need to buy to make it all happen.

After much consideration, weighing the pros and cons of every available desktop CNC google would show me, I settled on an X-Carve by Inventables, which is controlled by an Arduino that's running the open source g-code interpreter GRBL. Worst-case it hold a tolerance of 5-thousandths of an inch, which is pretty sloppy by professional fabrication standards, but is just good enough for my holographic endeavors. It also boasts a 31x31 inch work space, which is a far cry better than the size that most other machines offer. Some of them offer less than a foot of working space, but most of them have working area dimensions that are less than two feet. I want to be able to make holograms that are relatively large-format. Once you get too big, though, the fact that the light source isn't infinitely far away starts to interfere and distort the hologram, because each area of the hologram is then receiving incident light at more widely varying angles. This can be compensated for, but it's going to require special attention and more math.



The X-Carve CNC mill I aim to acquire for holographic purposes.
After a bit of research I've opted to go with 1/16th inch plates of 1100 aluminum alloy. 1100 aluminum is 99% pure, which is much more pure than all of the alloys, with the exception of 1050 and 1060. Pure aluminum is much softer to work with, and machine, with a Brinell hardness of 28 (copper is at 35, lead is 5, steel is 150). This means that the tiny cutters used to machine the hologram reflector grooves will not wear down as quickly, which is a good thing. 1100's softness and purity lend themselves well to optical applications, because it can be polished to a mirror shine without impurities mucking it up.

Another issue that cropped up was the fact that CAM software typically isn't designed to handle the sort of input that Holocraft generates. Typically, when importing a path of some kind, these programs like to assume it's a closed shape, that you either want to use as a hole, or an island/extrusion of some kind. In this case it's neither, I just want the machine to cut an arbitrary groove as output by Holocraft.

Of all the different high-end CAM software which I was able to locate trial-versions of to investigate, none of them were going to be able to import Holocraft data and use it properly. I was about to give up when I came across MakerCam, which is actually just a Flash applet that runs in a browser (http://www.makercam.com). By the grace of awesomeness it happens to do exactly what I need it to do. It will import an SVG that Holocraft outputs, and allows me a 'follow path' operation, and let me output the g-code as such. However, it struggles a *little* with the high number of paths that Holocraft outputs, which can be upwards of tens of thousands of individual little curved reflecting groove optics, which tempts me to just implement direct g-code generation capabilities into Holocraft. It would not be the first time that I wrote a program which generates g-code.


'Chamfer King' - One of the several CNC machining utilities that I wrote for my dad's CNC shop back in the day.

What I really need to do now is brush up on my 3D modeling skills, and start producing my own content to 'holographize' that actually represents my own creative self-expression, of which I have plenty to draw upon. I've only been testing out Holocraft using models on the various online repositories of 3D-printer models. There are some really decent paid models which would make some good holograms, but I'm more interested in making good holograms that depict what I want them to depict, not just what works.


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3 comments:

  1. thanks for the tips and information..i really appreciate it.. עיבוד שבבי

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  3. Hi Charles,

    I'm a graduate architecture student from Chicago and I'm really interested in your scratch hologram generating software. I was wondering if / when it will be available to download? I'm wanting to make some architectural holograms for my final degree show that's coming up in May and your software is absolutely perfect. I've tried writing algorithms in Grasshopper / manually arraying the arcs along curves but been having no luck.

    I'd love to hear back from you on this. My email is bnicholsonmedia@gmail.com

    Thanks!

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