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Re: Microvision's VRD

From: bph@primenet.com (Blair P. Houghton)
Date: Sat Jan 2 17:17:07 1999
Newsgroups: comp.sys.wearables

Ronald W. Garrison<rwgarr@intrex.net> wrote:
>through the entire raster. For a 1000x1000 image, the amount of time that
>the laser spends on any single spot should be something like one
>*millionth* of the total time. This means that the intensity of the light
>at any point on your retina will have a *very* high peak-to-average ratio.

TVs get a little help from phosphor decay, but to be any good a TV
phosphor has to decay faster than the picture rescans.  This is true
for computer monitors as well.

>So although your conscious perception may be that the brightness is not
>that high, any given receptor in your retina will get hit with some pretty
>energetic, though brief, pulses of light.

A little more than the photons coming off my computer monitor now,
maybe.

>millisecond or so. If you were scanning the raster at, say, 50,000 times
>per second, you could expect the eye to pretty much average things out. But
>if we're talking the usual figure of maybe 50-100 x per second, I could see
>some chance of problems of the type I've described. Maybe not even outright
>eye damage, but perhaps excessive vision fatigue.

Maybe they should be using higher scan-rates, then.  With the much
shorter horizontal beam skews, and the micromirror steering system
they're using, it could be possible.

>lying entirely within the triangle. You'd need new standards to cover the
>use of this new mapping, but the only real burden would be that your actual
>display would need to have six real, primary colors. That's where the cost
>would be.

It's uglier than just following the CIE diagram.  The eye
doesn't even see all those colors.  It sees three basic
distributions of colored photons and interpolates.  Three
"evenly-spaced" primary colors fakes it out okay, but there's
a lot we're missing and a lot of inefficiency we incur by not
having more sensors of our own.

>And of course, those head-mounted displays could ultimatley be just ideal
>for keeping those costs contained.

I wonder if we could use the micromirrors and some sort of photonic
prism steering to create a full-spectrum effect.  We'd need to start
with a highly collimated white-light source, though, which jacks up
the running temperature a bunch...

				--Blair
				  "3-D color night x-ray vision
				   that can see into the future!"

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