can I modulate laser for better tracking? 
Posted: 05 March 2012 11:23 PM   [ Ignore ]
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Concerning LLP laser, I am interested to know if somebody tried to modulate 780nm laser and by modifying CCV using passband adjusted on laser modulation, extract it and use it for a better tracking?
This way it is (I suppose) possible to eliminate erratic blobs.

Thanks for your feedback.

Davy
http://ca.linkedin.com/in/davyfraser

My 48 inch LLP table using Windows 8 Preview mounted on Virtual hard drive (VHD):

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Posted: 06 March 2012 04:49 PM   [ Ignore ]   [ # 1 ]
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By “better tracking” do you mean an increased frame rate on your camera (which is very very low)?  You need to use a faster computer, lower capture resolution or better camera in order to increase the speed.  Your blobs from CCV look good, though you should adjust the filters to make the blob spots smaller (perhaps turn down the amplify slider).  From what is shown on your video, changing the lasers won’t help you, you need to get the fps higher in CCV.

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Posted: 06 March 2012 11:47 PM   [ Ignore ]   [ # 2 ]
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Hi PeauProduction,

Thanks for your prompt reply.

It’s not a problem of blob or laser. It’s more to improve the detection of blobs and reject sunlight or light from lamp.

What I mean by modulate the laser is inject a frequency (example: square wave of 10khz) to the lasers.
The lasers will turn on and off at 10khz. On the CCV side, I modified the code and filter only this frequency.
This way you will be able to grab only blobs and eliminate other erratic blobs produced by lamp or sunlight.

I would like to know if somebody already experimented that.

Regards,

Davy

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Posted: 07 March 2012 01:59 PM   [ Ignore ]   [ # 3 ]
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What people have done is very similar in that they tapped into the vsync on the PS Eye camera and timed the LEDs/lasers to pulse at the same frequency.  Search around on the forums for more info.

To reduce issues involving sunlight and other ambient infrared light, you need to make sure you are using lasers that are higher then the typical 780nm wavelengths (those close to visible light).  We sell 850nm and 880nm lasers with matching band pass filters in our store to correct this exact issue.

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