I've bought a SY-IR53A - a quick google will give the specs. Here's where I bought it from:

http://www.maplin.co.uk/module.aspx?ModuleNo=2253&doy=23m1#overview

I've tried to work out what resistor I need but I'm getting confused. Can someone help?

I'm planning to use a laser pointer that holds 3x1.5V button batteries for a total of 4.5 volts or a single AA or AAA battery. I haven't got one yet but there's a few on eBay I've got my eye on.

Thanks in advance.

http://www.maplin.co.uk/module.aspx?ModuleNo=2253&doy=23m1#overview

I've tried to work out what resistor I need but I'm getting confused. Can someone help?

I'm planning to use a laser pointer that holds 3x1.5V button batteries for a total of 4.5 volts or a single AA or AAA battery. I haven't got one yet but there's a few on eBay I've got my eye on.

Thanks in advance.