Measuring Specific Light Frequencies [TSL2561]

[fraguada]

Hello all!
I bought a TSL2561 on a bob and I must say it is a very nice piece of kit! Super easy to get started. I was looking for something which would give me values I could relate to other instruments, and this little piece is getting the job done.
Now, I am wondering if we can do a bit more with this sensor, but perhaps I need to get my concepts straight. This is where the community might be able to direct me in some directions.
I am interested in measuring the amount of a specific wavelength of light. Now, with audio/noise, I can use FFT functions to split out the frequencies and see how strong a particular frequency might be. Can I do the same for a signal coming from the TSL2561 or other photodiode? Perhaps I am not even in the correct ball park about this sort of stuff. So to summarize:
1. Can the TSL2561 be used to measure the intensity of a specific light wavelength?
2. If so, what would be the way to go about it?
3. Can FFT be used to take care of such a task?

Thanks!
Luis

[adafruit_support_bill]

By itself, no. The sensors on the module are sensitive to two overlapping ranges of wavelengths. It cannot discriminate light contributed at specific wavelengths within that range.

The sensor could (with the addition of some optics) be use to build a spectrophotometer. But this is easier to do with a CCD or photodiode array than with discrete sensors.

[philba]

Being a hw hacker, I've always wondered if I could use the ccd line sensor from a scanner to build a spectrum analyzer. I still see junk scanners for free (and "working" ones for $5 in thrift stores). Lots of nice parts in them but never knew what to do with the line sensor. I suppose calibration would be an issue. Maybe use several different LEDs with a known spectrum. Could be a fun project.

[fraguada]

thanks for the information and suggestions! While I had the feeling that this was the case, I thought I would ask.