Lazer/ Laser "Globe / Starmap"

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benscammell

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Ok so this is a big, expensive project, which will go slow... may never happen, but if it does... will be epic.

Using a 100cm acrylic sphere, frosted by shot blasting, project on to the inside surface an outline of every country / continent or starmap etc. using an RGB laser...

Then find some way of sensing touch on the sphere surface to make the globe spin as you touch and move your finger over the sphere.

This project has a (good) budget, and has to use Teensy somewhere!

Anyone got any ideas?

Anyone want to get involved?

Cheers, Ben
 
My suggestion would be take it in steps:

Learn about laser safety
Obtain all relevant safety materials, such as goggles, etc.

Consider whether other light sources might be better. For example, a digital light projector would allow much higher resolution, but probably wouldn't be as bright. Assuming you do go with the laser approach, the following steps come to mind.

Method of sensing touch gestures on a flat surface
Method of sensing touch gestures on a flat large surface
Method of sensing touch gestures on a curved large surface

Method of steering a monochrome laser (laser pointer?) electromechanically
Method of steering a monochrome laser with a Teensy

Method of projecting a monochrome laser imagine on flat frosted acrylic plate
Etc.

Once you get an idea of what level of detail is possible, it would be a good idea to put thought into what you'll project. It would be a bummer to build a big thing only to realize that the image quality wasn't sufficient to make your dream come true.



Did not know "RGB laser" was a thing. Turns out it's a shorthand for a system with a red, a green and a blue laser.
 
What could possibly go wrong? ;)

lasers.jpg
 
benscammell said:
This is an area where I'm drawing a blank...
Click to expand...

It's common for stovetops with touch sensors to use reflected IR sensors. A finger reflects the light back to a photodiode and that signals a button 'press'. I wonder if your spinning mirrors could be pressed into double duty? I.e. a photodiode aimed at the mirrors should sense a difference in the reflected light from the lasers when the surface of the globe is touched by an opaque object than when there is nothing near it.

Another alternative that would be pretty labor intensive would be to run a grid of very thin wires inside the globe for capacitive touch sensing. I'm really scratching my head about how you'd get in there to precisely affix them to the inside unless the globe was composed of two hemispheres. Also to get decent resolution, it would take lots and lots of wires.

Yet another alternative would be to put the touch sensor outside the global. For example, mount a camera above the globe pointing down (or mount several cameras). Aesthetically, I don't like this approach because the object ceases to be a single simple portable thing and becomes an installation with weird limits on where the gestures work.

A cheat that would definitely work and would be really simple would be to mount a trackball near the sphere. It's not nearly as cool, but if you'd rather have something that works than a dream that's hung up on unavailable tech, it's an option.
 
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