Hi again,

I came across these LEDS on Farnell : SFH 4252

They are 850 nm, 120 degree leds. I am not sure if the power is good enough. I have attached the datasheet. I am very confused the power output, how much is good, how many mW/Sr etc.

Also i have attached the plan for placing the LEDS. i plan to place two strips( each having 24 leds equally spaced) in the box.

Please advice.

Thanks

Osman do you have soldering station to solder these SMD? These are very small leds and you can’t or it is very difficult to solder them on a PCB… check this first

Yeah good luck with surface mount LEDs!  It is possible though and yes is you do the maths you could end up with a powerfull and tidy little package.

You will need to print your own circuitboard and have either a solder bath, reflow oven or a very steady hand to solder them on to the board.

Good luck!

I understand that, and hence i am trying to find someone who can do it for me. So the LED specs are ok?

cool,

Not sure about the amount of LEDS you will need.  Perhaps consult the NUI bible http://nuicode.com/projects/wiki-book/files

and the led calculator http://led.linear1.org/led.wiz

Also with DI it is worth bouncing the IR of the side walls

Cant be much more help than that tho!

i am currently using 4 48 led illuminators, bouncing then off walls. But i am not sure of the illumination (angle, distribution etc.).  its working, but i am looking at a more engineered solution, such that all led power is directed towards the screen, without creating hotspot or uneven illumination

i am planning 24 leds per side, spaced at 1” from each other. I could make it 48 also if required(spaced half inch apart), but how powerful are the leds? i am not sure about that. If somebody could look into the datasheet and guide me if the leds are powerful enough?

Thanks

then why dont you plan to build a FTIR table form scratch?

Fiducials. So no other option, only DI

Self iluminating fiducials! But i digress, yep its a tricky one, having only built an LLP setup i cant really provide any really usefull comentry.  Try the reactivision guys as the reactable is a solid device.  also trawel through the showcase.

Hi Osman,

looking at the spec. on those LEDs they are only 10mW/Sr which means their light is very dim spread over an area. I don’t think you will have enough light from only 24 of these LEDs as typically DI setups use a lot more.

I’d bring them closer and angle them different than your diagram for a start, perhaps aiming them from one side on half the table and on the other side to the other half.

Alternatively if you are placing them as low as in your drawing then putting something to bounce their light on the side of the table rather than waste half of it is an idea.

bamalam

Hi bamalam,

In the diagram i have mentioned “similarly on this side” on the other side. I mean, i intended to use a similar 24 led strip on the opposite side.

I think you are right about the low power, so i guess i will increase the number to 48 “per side”, i e 96 in total.

or should i make it 72 per side, 144 total?