Need help with my project- Virtual Keyboard

hi, im working on this project called the virtual keyboard. the details can be found at 


im facing a few problems, projection module requires for the use of a holographic plate to project the image of the keyboard on the surface but this stuff isn't available to me so i'm searching for alternatives, i've tried projecting the image using light and a plastic sheet instead but it did'nt work. i  also tried working with infrared light but the spot size is too small and would require a diffractive image to correctly project the image due to its compact siz

kelseymh6 years ago
From your description, I presume you're actually working on an optical projection keyboard, correct?

The way the commercial products seem to work is with POV.

Rather than projecting a static image from a plate (as you're trying to do), they use a laser pointer to draw and redraw (presumably by moving a small mirror inside the unit) the keyboard on the table top 24 or 30 times per second. That requires memory to store the image (pixel locations or vectors) and a microcontroller to drive the mirror properly to make the drawing.

Your method is more robust, except that, as you see, it's hard to make a sharp image. You should be able to do something with a proper lens projection system (just a sheet of plastic and light won't project anything), but you'll need to anamorphically distort the master so that the user sees a properly shaped keyboard on the tabletop.
ameenyousuf (author)  kelseymh6 years ago
yes i'm working on an optical projection keyboard.

i tried working with convex and concave lenses as well but it resulted in the laser diode to loose its coherency and a compromise in coherency would mean that the image that i'll won't be sharp. T
he beam that i got after expanding the beam from the laser diode(through lenses) didn't expand as i assumed that it would.

I knew the plastic sheet was naive idea but i just had to try it before ruling it out completely.
kelseymh6 years ago
This is not a bug report. Moved to Forums:Technology.