

DIY Retinal Projection - bcjordan
http://eclecti.cc/hardware/blinded-by-the-light-diy-retinal-projection

======
logn
I generally don't tackle projects that have the words "DIY", "retinal", and
"laser" in the description.

Granted, the author addresses safety issues.

------
jonmrodriguez
Awesome stuff!

The cool thing about a laser projector is that unlike with a lens-based
projector, there is infinite depth of field:
<http://www.amazon.com/review/R1S9P57VXN5LSH/>

But I think there should be some regulation on legal maximum instantaneous
brightness. Per the review I linked, the projector used in this project has a
848 x 480 pixel framebuffer. But the laser bounces off a scanning mirror, so
at any given time, only one pixel is bright as day and the rest of the pixels
are black. This means that the actual power being zapped into your retina is
about 400 thousand times brighter than what you perceive. Have there been
experiments over the long term to make sure these don't cause retinal sunburn?

~~~
jacquesm
As long as that mirror is moving there is no problem, but if it should ever
stop you're in immediate trouble.

------
jacquesm
Seen on the outside of the casing of a laser projector: "Do not look into
laser with remaining eye". That one was a bit more powerful than this one but
the point is still valid.

The problem with a setup like this is that in case of deflection failure if
you're not projecting into someone's eye that results in an annoyingly bright
line but not much else. If you are projecting into the eye then you could
quite possibly do a lot of damage, in an eyeblink (to use a bad pun) at that.

So it's not just enough to deal with reducing the amount of light put out on
average to be safe. You also need to deal with failure modes to get the laser
to shut down _immediately_ if anything puts the actuators out of order.

------
daniel-cussen
I'm surprised how useful 3D printing turns out to be for this kind of
application.

~~~
robbiep
It's turning up everywhere now for the DIY crowd. Might be stating the obvious
but really seems like personal 3d printing is hitting a high saturation
amongst those serious enough to blog.

The upside for me - So many interesting projects to read about!

