LASERS! && Freemont Street LED array (was Re: Cray J932SE (was Re: Straight 8 up on Ebay just now))

Paul Koning paulkoning at
Tue Jul 19 15:20:02 CDT 2016

> On Jul 19, 2016, at 4:02 PM, Mouse <mouse at Rodents-Montreal.ORG> wrote:
>>> Light show hobby.
> You'd probably know, then - what's the fastest way to deflect a laser
> beam?  In particular, I'm wondering how practical it might be to take a
> laser and turn it into a vector display on a handy blank wall - but
> that requires some very fast acceleration of the spot, probably faster
> than mechanical deflection can support (though if I'm wrong I'd love to
> know it).  For example, does piezoelectricity make a crystal distort
> enough to use it as an optical deflection element in such a scheme?
> (My guess is no, but I don't actually know.)
> I have SPARCstations with cg6s that I can use as vector displays, but
> they are vectors converted to raster.  I'd like to do real vector - a
> parallel port driving a couple of moderately fast D->A converters might
> be able to do it; it might take something better, dunno.  But without
> the deflection mechanism there's no point in even trying to design the
> rest of it.

What bandwidth (deflection rate) do you need?  Full scale in a microsecond?  In 10 microseconds?

Piezoelectric loudspeakers work up into ultrasonic range.  A mirror attached to such an actuator would give you variable deflection.  So 10 microseconds might be doable.

A faster (no moving parts) scheme might be to use Kerr cells.  I don't know if that has been done, but from what I understand about the Kerr effect it seems plausible that it could be.


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