A challenge for you expert folks.....about tennis!!

[Electrobrains]

These laser modules are less than $1 delivered, if you purchase in bulk...

http://www.dealextreme.com/p/2-5mw-focusable-dot-laser-module-4-pack-3v-46390?item=18

That's an interesting source. I have been looking for low-cost laser modules in the last weeks!
It seems they even have adjustable focus.

 

[CocaCola]

That's an interesting source. I have been looking for low-cost laser modules in the last weeks!
It seems they even have adjustable focus.

They are a decent company to deal with, BUT they can be VERY VERY slow to ship, or they could ship same day it's real hit or miss... I have ordered from them for years, they always deliver but you just don't know when or how long it will take... My advise is that since it's free shipping, if you are ordering multiple items place separate orders spaced out over a few days, as they won't do a partial shipment if you place a big order, thus if one part is not in stock they will hold the entire order...

 

[Electrobrains]

I have a similar project, where a laser beam will send signals a longer distance.
I have not had much time to look for a good receiver yet. It should have as big area as possible and react if only a small (red or maybe IR) laser spot hit part of it.
I made some tests with an LDR, but the spot seems to be too small to give much reaction. A photo diode works well, but the surface is so small that it is difficult to adjust to that spot. Of course a lens could be used, but I find that solution not so attractive...
I did not test photo voltaic material yet.

Question: Have you used laser diodes in the manner discussed here? Any good receiver?

 

[CocaCola]

Question: Have you used laser diodes in the manner discussed here? Any good receiver?

Beyond the basic LDR no at short distances no, but from what I have seen most commercial solutions will use a lens...