Author Topic: Re: Vishay TSAL6200 - Can it be used  (Read 8284 times)

Offline Gavin

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on: March 14, 2009, 10:19:07 PM
I've been investigating what IR LEDs Vishay makes to see which would be good for IR pen.

You want a wide angle so if you tilt the pen it still works, but you also want it bright enough.
The wider the angle the light is disbursed over, the less intensity at any point (i.e. the camera)
It's just like spraying a garden hose: on JET all the water goes to one place, but you have to point it.
on spray everything gets wet, but not a lot.
TSAL6400 is 25 while TSAL6200 is 10   ... btw, TSAL7400 is the same as the TSAL6400, but in a clear case.

Another consideration is wavelength of the light (nm) Wiimote can't see light we see or it would have too much "noise" to find the signals. Human vision sees from 400nm to about 760nm. Most of you have been using 940nm LEDs, I know the filter in front of the IR camera blocks to about 800mn, (has anyone measured it's absorbtion spectrum?). The thing is 830 to 890 nm LEDs are available and some are brighter (there is also better quantum efficiency, both in making the light in the LED and absorbing it in the camera), so 850nm and up should be fine. Let me know if anyone knows differently.

Anyway because everyone who isn't making IRpens for Wiimotes is busy lighting up security cameras, ;-)  there are lots of bright IR LEDs, many new to the market:
Here are a few to try in decreasing order of preference: (Get the one you can find as close to the top of the list as you can.)
TSAL6400   T-1 940nm   25    40mW/sr
TSAL7400   T-1 940nm   25    40mW/sr
TSHF5210  T-1  890nm   22  180mW/sr
TSHF5410  T-1  890nm   22    70mW/sr
TSHF6410  T-1  890nm   22    70mW/sr
TSHG6400  T-1  850nm  22    70mW/sr
TSHG5510  T-1  830nm  38    38mW/sr   Really wide but less bright, good in small room.
TSAL7600   T-1 940nm   30    25-75mW/sr   wide, less bright, good in small room, or with multiple cameras

If you are making a stick with the LED on the back and camera behind you
or to the side, try these surface mount chips, wide smooth beam, but flat top so not good for a pen.

Vishay VSMG3700    850 nm    60    10 mW/sr
Fairchild QEB421      880nm     60         48mW/sr

If you want to do the Johnny Lee tape on your fingers and wave your hands to make music or draw or whatever, you want a source of light that is a narrower beam, and you will need lots of LEDs to make it bright try these:
TSFF6210        870nm      10          90-180-450       

Forget most of the Lite-On and Everlight LEDs they are too dim, except
Everlight HIR5393C-L223  10mm  850nm  25 deg  150-200 mW/sr
A big 10mm LED that's really bright.


Offline benpaddlejones

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Reply #1 on: March 14, 2009, 11:23:25 PM
I suggest you read:!-***-updated-***/

Its a little more complex than those stats. Don't waste you time with anything away from 940nm as this is the wavelength at which the filter is set. You also need to look at the relative radiant power vs wavelength and relative radiant intensity vs angular displacement.

Just stick with the TSAL6400 TSAL7600 or TSAL5300 and you can't go wrong.

When I did some functional tests nearly a year ago I wrote most of your list off, simply because the Wiimote struggled to even see them, let alone track them.

benpaddlejones :)

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