This is a simple test using 2 850nm IR 5mW laser diodes with line lens emitting a plane directly above a 19” LCD monitor. The camera is a Microsoft VX-6000 with an 850nm IR pass lens installed. I’m not using any other acrylic or filters. This is my first attempt at multi-touch but it seems to work OK despite not having any acrylic sheet to provide FTIR. I am directly touching the LCD panel which is on top of 2 sawhorses.
Here is a video:
Nice work! I’m interested in knowing what the smallest object detected can be. If you get a chance can you make video, pics, or just your words on how a pen/pencil does with this method and whether something that small will work with this technique?
@nuiman: what’s the need for a compliant surface if it’s not FTIR?
cerupcat, we can play with our table (fingerpuk.tumblr.com) with pencils, even a hair clip was tracked. Brushes etc for paint apps is no issue at all. With lasers I think releasing ants onto the surface could be great fun.
Nice , your blobs are really bright and big , great job. Where did you get the lasers and the lenses?
I got them from this eBay store for $29.50. The line lens was an additional $4. I built the adjustable holders with angle aluminum, UHMW, 10-24 nuts and threaded rod. The aluminum also acts as a heatsink. They have built-in power regulation so they can be powered from an unregulated 3V DC source. I did some research and the laser diodes from a regular CD player should also work. However, you would have to build a laser power supply. I also bought Glendale laser protection glasses from this other ebay store for $19.99.
Nice work! I’m interested in knowing what the smallest object detected can be. If you get a chance can you make video, pics, or just your words on how a pen/pencil does with this method and whether something that small will work with this technique?
@nuiman: what’s the need for a compliant surface if it’s not FTIR?
Small objects work well. In fact dust and lint show up on the screen and need to be clean before use. However, black items don’t work as well as white items. The more reflective the object the better the blob. The biggest problem I have now is sunlight. Here is another video showing a mechanical pencil. It is filmed in a room flooded with sunlight so the contrast is poor. I dragged the eraser and then the tip with no lead.
Thanks for the answear , I’m not from the US and I see the guy with the lasers dosn’t ship worldwide , I’l probably have to get some from cd-roms , the big problem for me is where to get the line lens you used ?
Thanks for the answear , I’m not from the US and I see the guy with the lasers dosn’t ship worldwide , I’l probably have to get some from cd-roms , the big problem for me is where to get the line lens you used ?
I believe you could make a line lens with acrylic rod. I did a test with a glass. Even though the stem is not perfectly cylindrical, the line still looks OK.
Here is a good site with plans for several power supplies.
