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Graham Stabler
11-15-2006, 10:26 PM
Does anyone know of any line cameras that might be interfaced easily with the propeller and don't cost the earth?

Graham

Phil Pilgrim (PhiPi)
11-16-2006, 01:25 AM
Graham,

Are you referring to a 1xN linear array? How many pixels do you need? How fast do you need to be able to obtain one scan?

-Phil

Graham Stabler
11-16-2006, 02:54 AM
Yes a linear array.

I just want to find out what is available, I'm thinking about using it for optical triangulation, the more pixels the better really. Speed, well I want to track leds so something along the lines of 30fps I guess but I suspect it could be lower.

I've used Hamamatsu arrays at work but that was with an expensive DAQ card, they provided a pulse per pixel that was proportional to intensity with a rolling shutter.

Graham

Phil Pilgrim (PhiPi)
11-16-2006, 03:13 AM
Graham,

The reason I asked about pixel count is that TAOS (http://www.taosinc.com/category.asp?cateid=3) offers some nice low-resolution (102-, 128-pixel) CMOS sensors. The 102-pixel (TSL3301) unit has a digital serial output and would interface nicely with the Propeller. The others are analog, but may still work in a delta-sigma environment. (In fact, I have a board for the TSL1401R that plugs into my MoBoProp board. I just haven't had time to try it. It was actually designed for the MoBoStamp-pe, which has analog input.) For either unit, 30fps is a piece of cake.

TAOS offers larger sensors, but they're physically large, too, and would require larger and more expensive optics. The smaller units work nicely with cheapy M12 board-cam lenses.

Now, 128 pixels may not seem like a lot. But for your app, it may be plenty, depending on how many LEDs you need to view at once. If it's just one or two, resolution can be improved by defocussing the image a bit and using sub-pixel interpolation (i.e. finding the centroid of the resulting Gaussian response curve).

-Phil

Cliff L. Biffle
11-16-2006, 04:44 AM
TAOS's site is also pretty quiet when it comes to prices, but the parts are available from Mouser and others.

Here's the Mouser link: www.mouser.com/search/ProductDetail.aspx?R=TSL3301-LFvirtualkey57530000virtualkey856-TSL3301LF (http://www.mouser.com/search/ProductDetail.aspx?R=TSL3301-LFvirtualkey57530000virtualkey856-TSL3301LF)

Graham Stabler
11-16-2006, 08:12 AM
Thanks for the links, they are certainly interesting devices and good prices too.

I think I'd be using cylindrical lenses else the image will drift off the array. The leds will be turned on one at a time in fact it would probably go something like:

no LED, LED1, no LED, LED2 ......

To allow easy subraction of the background. In fact it is quite possible to do full 6dof positioning with several leds and a 2D array I'm wondering if you could use a relatively high res camera because you don't actually have to store full frames but rather look for the brightest pixel or similar.

Anyway it could be fun, I know they use IR leds for this stuff in industry to avoid ambient problems but I was thinking of trying blue SMT LEDs and a blue filter to start with as I have some.

Graham