This invention relates to a practical low cost method and devices which exploits the benefits of several photo-assisted analytical techniques involving controlled light sources. The method comprise the use of a program controlled display (like computer, mobile telephones to TV screens) used as a light source for illuminating a detector specially suited to capture the light interaction with a test environment, allowing to generate distinctive spectra and chemical or biochemical images of the environment. Additionally, the information can be acquired in situ but immediately analyzed on line via internet.