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Laser Powered Virtual Display
Tedger writes "The Feature has an article discussing an interesting portable display system developed by the University of Washington. Unlike your traditional mini displays mounted in glasses this system has no display, it is a 'virtual' display created by lasers and microscopic fast moving mirrors. The image is in fact printed onto the retina and has feasibly a infinite resolution. Can anyone say true VR?"
I recently read a book "The Visionary Position" which detailed the university of washingtons virtual reality lab and all of the various spin-off companies.
It wasn't a bad book, but they've had these things since the mid-90's -- just hard to find an appropriate market I guess.
"But actually trying to use m4 as a general-purpose langage would be deeply perverse" --ESR
Didn't we see this already?
A CD-ROM laser could hardly hurt your eye
Not instantly, but because it is IR, by the time you notice anything, the damage has already been done.
Just because you can't see the laser doesn't mean it sn't dangerous.
I used to work for a company that produced a High Resolution Display that used mirrors to steer a red or blue laser beam onto a sheet of photochromic film - the blue laser would permanently write on the film - the red laser could be used for drawing small amounts of vector graphics - a cursor, or a few characters of text. Doing complex graphics in vector mode when the persistence of the human eye is less than 40ms will require the mirror to be scanned at very high frequencies
Laser light is fundamentally different from natural light ... its a coherent group of photons; all approximately in phase, traveling in the same direction with roughly the same energy. This stuff isn't normally encountered in nature. Its hard to say what long term exposure to this sort of radiation is going to do to sensitive tissues like those found in human eyes ...
I'm being general here; not saying it couldn't be safe. In any case its completely different from looking at light scattered from a screen, staring at a light bulb filament, or seeing an image formed by separate little light-sources (pixels) on a CRT.
They must have diffraction/interference problems stuffing a laser straight into an eye like that?
Okay, just a few things about this and some problems.
... bah, it's enough already.
Microvision is the company doing this.
What about saccades? When the eye moves rapidly over a long angular direction (which it does in tracking objects or changing your view) or a short angular direction (a.k.a. microsaccades, which happen multiple times a second), you get blurring which is normally suppressed by the visual attention system.
When you do saccades across long persistence displays like LCDs, you will not see any major aberration as the light source effectively stays on. When you saccade across medium to short persistence displays (P21 phosphors for short, your regular TV or CRT for medium), it is possible to notice that there is either a shearing or tearing artifact.
TV/CRT displays are scanned left-to-right at (say for 640x480 VGA at 80 Hz) 480*80=38400 times per second and scanned slow...ly up-to-down 80 times per second followed by that quick scan back up. Well you can try this at home (TV's at ~60 Hz show this a little more easily than most of our CRTs which are set at a less-likely-to-appear to flicker refresh of >80Hz):
look at an object to the left of the TV screen. Then rapidly switch what you're looking at to the right side of the TV screen. The image of the TV will no longer look rectangular but like a shortened-horizontally and sheared (top to the leftish, bottom to the rightish) parallelogram. If you do a right-to-left saccade, the image will appear longer horizontally and top to the rightish of the bottom.
Now the interesting thing happens with up-to-down saccades: if you go up-to-down at slower than or close to the same angular velocity as the scan line (depends on how close you're sitting to the screen) goes down the screen, the projected image will appear SHORTER-UP-TO-DOWN and if you actually match the scan-line's downward angular velocity, the TV image will seem to just be a poorly set up XF86 display of one pixel in height.
If you have an effectively ZERO-PERSISTENCE direct write display, since the laser is being used to draw directly on the retina (or to project on a screen) rather than an electron-train hitting chemicals causing them to phosphoresce with a certain limited time before they stop glowing (PERSISTENCE...), then fixation has to be maintained or the illusion of motion based on the projection's position is destroyed. Laser projection systems try do multiple lines scanned at once or other fancy projection scan patterns rather than the usual cathode-ray-gun approach, but the saccade problem continues to be an issue.
The saccade errors are the big to-do with projective laser displays for visible wavelengths, regardless of whether they are projected onto a screen or direct write onto the retina.
The other problem is