Lasers

Has anybody ever tried:

1. ) using two oscillating mirror (mounted to the end of the motor shaft on a wedge) with (very) different speeds to generate a Lissajou pattern with a large number of left-right oscillations per up-down oscillation. see: http://www.hut.fi/~then/mytexts/lasercontrol.html
2. ) software map the original raster pattern to the Lissajou pattern. I.e. spread the pixels where the beam is traveling slow (at the edges) and compress them where it is traveling fast (in the middle)
3. ) electronically modulate a visible laser diode with the pixel data with the start of each scan line triggered by the beam passing a photo diode between the first (horizontal) and second (vertical) mirrors and frame synced by another after the second mirror

The point here is that the two motor driven mirrors can spin very quickly with little current draw while generating an (almost) raster scan pattern that is corrected for by software. You can reduce the need for mapping by not starting the scans until the beam is a bit away from the edge.

Andy Howard says:

A technique similar to this was used in some of the very earliest electro-mechanical TV experiments. Spinning drums with mirrors attached all around to form a regular polygon were used to give scanning with near-instant flyback.

I've recently seen a similar-looking arrangement used with a lightshow laser to project computer-generated video snippets.

Wearable HUD discussion

Laser Serial Links

Fiber Optic

See also:

• http://www.metrologic.com/vsts1095.htm
• http://www.ti.com/dlp

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