A method for assessing an interaction of a sample with light beams having different wavelengths, the method comprising: generating a light beam having a wavelength and being intensity modulated according to a modulation function to create an intensity modulation in the light beam; irradiating the sample with the light beam; detecting a response light from the sample, the response light being released by the sample when the sample is irradiated with the light beam, the response light having intensity fluctuations caused by the intensity modulation; using the intensity fluctuations in the response light to identify the modulation function and associate the wavelength and the response light to each other; assessing the interaction of the sample with the light beam using the response light; stopping irradiating the sample with the light beam and performing the previous step with at least one other light beam having a different wavelength. The modulation functions provide wavelength information in the light beams by encoding the wavelengths in the light beams, the wavelength information being conveyed in the response lights to allow association of the response lights respectively with a respective wavelength.