Author Topic: IR chopsticks  (Read 3849 times)

Offline ethankennerly

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on: February 15, 2008, 12:50:58 PM
In pursuit of a cheap, expressive interface for a school project, wii media lab, I've been considering chopsticks for 3D modeling.
http://interactive.usc.edu/members/ekennerly/2008/02/wii_media_lab.html

I've tested using two IR LEDs sources, with button batteries on the tips of chopsticks, but when the chopsticks are not pointed at the wiimote, there is insufficient radiance.

The test supplies were cheap and trivial to assemble:  two cheap 1.5v button batteries, two 1.6v (max) IR LED, a bit of electrical tape, and disposable bamboo chopsticks.  The legs of one LED are directly attached to the button battery and this is tightly wrapped around the tip of a chopstick.  (For those not dextrous with chopsticks, this general configuration is also small and light enough to tape around one's finger without strain.)  Although crude, it was good enough for a test. 

I'm trying to get a wider angle LED source.  Lightly sanding the LED surface did not seem to increase its viewing angle.  I'm using 45 degree LEDs from radio shack and have seen 60 degree angle LEDs elsewhere, but I need about 90 to 120 degrees.  The idea occurred to use multiple LEDs at differing  angles, as is done in the sensor bar, but that seems less efficient than a single wide-angle LED.  Does anyone know of a 90 to 120 degree angle single infrared LED with decent brightness?

So far I've come across:

Wide angle infrared LED?
They exist but the radiant power is usually low.
http://www.ledtronics.com/ds/SML10IR941T/
http://www.ledtronics.com/ds/SML10IR941T/DSTR0125.pdf

60 degree angle LED exists.
http://www.rentron.com/remote_control/IRLED.htm
http://www.ledsupply.com/l2-0-ir3th60-1.php
http://superbrightleds.com/specs/IR2730_specs.htm

I did see one IR LED reported at 120 degrees, but its frame is bulky for a chopstick.
http://www.roithner-laser.com/LED_HP_single_chip.html
http://www.roithner-laser.com/All_Datasheets/LEDs/M3L1_series.pdf

As Johnny demonstrated, I could use a reflective surface on the tip of the chopsticks, with an IR array, but I'd prefer having a wide angle IR source on the user, if that's feasible.

-- Ethan
« Last Edit: February 15, 2008, 01:00:22 PM by ethankennerly »