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Author Topic: Can the Wiimote be modified to support visible light?  (Read 20685 times)

Offline shobley

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on: January 28, 2008, 09:57:07 AM
Hi,

I have a question about the Pixart sensor on the wiimote - is this a regular image chip with a visible blocking/IR pass filter on the front?

Is the filter removable?

I have some 532nm pass notch filters, and it would really help my laser harp project if the wiimote IR sensor could be turned into a 532nm sensor.

Failing that I could add an IR laser to the mix, or just attach some IR leds to my hands - but getting it to work with the visible spectrum would be ideal.

Steve
« Last Edit: January 28, 2008, 11:02:17 AM by shobley »


Offline shobley

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Reply #1 on: January 29, 2008, 10:29:12 AM
OK, let me rephrase that...

Does anyone have a picture of the front end of the camera sensor on a Wiimote with it's casing off?

While I await the arrival of my "magic" screwdriver...


Offline Azel

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Reply #2 on: January 29, 2008, 12:38:05 PM


Offline shobley

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Reply #3 on: February 16, 2008, 07:39:19 PM
I managed to get the laser harp working OK without the wiimote -

quick video demo here:
http://www.youtube.com/watch?v=sLVXmsbVwUs

but it strikes me that this is the *perfect* application for a WiiMote - the players hands could be tracked with just the Wiimote alone.

If the bloke on Ebay that sold me the tri-wing screwdriver *ever* ships the bl**dy thing then I might have a chance of getting this running.
 >:(
DOh!

Steve


Offline shobley

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Reply #4 on: February 25, 2008, 11:02:28 PM
YES!!

The Wiimote can be modified to track visible light.

I finally got my tri-wing screwdriver tonight!  :D

I took the front IR filter off, and fitted a 532nm notch filter - the wiimote was able to track a 532nm laser pointer.

I am soooooo adding this to my laser harp gizmo.

Steve
www.stephenhobley.com/build


Offline paolo2648

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Reply #5 on: March 07, 2008, 09:53:50 AM
NO WAY!  :D  This is FANTASTIC news!!

How does the filter work then?  I'm a total newbie in this area...  I would have thought the filter filtered out 532nm?  How would the camera see it?  Also, where would one go about procuring a filter of this type  :D
« Last Edit: March 07, 2008, 10:18:09 AM by paolo2648 »


Offline inio

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Reply #6 on: March 07, 2008, 10:20:41 AM
The filter is the dark window in the front of the Wii Remote.  The camera itself doesn't have any filters, so if you disassemble the Wii Remote and remove the window, it can detect any source.


Offline paolo2648

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Reply #7 on: March 07, 2008, 12:42:59 PM
I was wondering about this -

"I took the front IR filter off, and fitted a 532nm notch filter - the wiimote was able to track a 532nm laser pointer"

as I want to track a green laser.  There's other tracking software out there but this just seems to work.  Fingers crossed...


Offline inio

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Reply #8 on: March 07, 2008, 01:00:07 PM
Ooooh, a "notch filter" allows a specific frequency (wavelength) to pass through it.  lasers emit light with an extremely narrow wavelength band.  Most lights, however, have extremely broad spectral emission characteristics - a few examples can be found here.  matching a filter to the laser wavelength allows you to see minimal ambient light and still get 100% of the laser light.


Offline paolo2648

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Reply #9 on: March 08, 2008, 04:24:40 AM
Excellent.  That's what I wanted to hear/read  :)

I would have expected it to be the other way round - only filter out 532nm...shows you how much I know   ;D

Would something like this do - http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1736

Thanks for that.  I notice there's another thread on the forum that's looking for info along the same lines as this.  I'll try and find it and point them back here.
« Last Edit: March 08, 2008, 07:24:59 AM by paolo2648 »


Offline inio

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Reply #10 on: March 08, 2008, 11:55:59 AM
Actually, looking at wikipedia, both the original poster and I are wrong about notch filters.  They block a particular wavelength. 

If you're using a green pointer (532nm), the filters you linked to wouldn't work at all.  You want a 523nm filter with as small a FWHM as you can afford, 10nm at worst.  Edmund is the right place to be looking, but what you want is unlikely to show up in the clearance section.  You could also look at THORLABS, but they tend to be a little pricier.

However, finding a filter that will work may prove pretty tricky if you want to use the full FOV of the Wii Remote.  Most filters are only spec'd for "collimated" input - meaning all light is arriving perpendicular to the filter - and performance will vary as you get more than a few degrees off-axis.


Offline paolo2648

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Reply #11 on: March 09, 2008, 08:28:46 AM
These were the lenses -



So - back to the drawing board for now...
« Last Edit: March 09, 2008, 11:27:08 AM by paolo2648 »


Offline paolo2648

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Reply #12 on: March 09, 2008, 12:56:38 PM
Thought this may be of use


taken from - http://wiibrew.org/index.php?title=Wiimote#IR_Camera



Offline sha

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Reply #13 on: March 14, 2008, 08:24:33 PM
I took out both filters: one large piece of plastic in front of camera and the other built-in coated glass filter:

http://www.youtube.com/watch?v=WsvK7Euwa-I


Offline paolo2648

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Reply #14 on: March 15, 2008, 05:22:10 AM
Liking it!  My Wiimote still hasn't arrived - SO frustrating seeing all this going on and I can't get my hands on it  >:(

Keep the info coming...


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