Red light sensors

I'm assuming your looking to measure the intensity of red light. The only thing I can think of is to take a portable lux meter and put a red filter and a IR blocking filter (Hot Mirror) over the detector portion. This should give you a passband of 600nm-800nm (Red light). To find a Lux Meter, go to www.globalspec.com and type in "Lux Meter" into the search box. Select the Lux Meters(Light Meters) result. This will return a list of companies that makes Lux Meters. You'll have to register in order to view the product results. You can also find the Red filter in our "Color Filters" category and the IR Blocking Filter in our "Hot and Cold Mirrors category. I hope this helps, good luck!

If you have control over the light source, modulating it and then demodulating it at the detector is a good way to filter out noise, ambient light, etc.. It might even eliminate the need to detect only a specific color, depending on your application.