Detecting and identifying different light sources in arduino?

Question

I want to detect different light sources in arduino. The first Idea about solving this problem came into my mind was to add three light detection sensors (LDR, IR receiver Diode and Photo transistor) to combine them and put the outputs of these sensors to analog inputs of Arduino. And after that analyse data according to different light sources (for example Bulb, Tube light, Lighter flame and Sun light) and finally make check according to these data.

My question is, am I approaching problem correctly? Or is there any better but cheap approach toward this problem? because I cannot arrange spectrometer or any sensor to measure spectrogram of the lights.

What is the correct way to detect and differentiate between different light sources?

Answer 1

Have you considered using a number of light intensity sensors (type doesn't really matter), each with a different coloured filter over them? A few different colours from different parts of the spectrum would essentially be a simple spectrometer. Optical bandpass filters aren't particularly expensive. Selecting 3 or 4 points in the spectrum (visible or invisible) might give enough data to differentiate between light sources.

There's a range of "DIY Spectrometers" documented online using different techniques. Some people appear to use CDs or cheap diffraction gratings (for example from toy glasses).