Abstract: A system and method for analyzing biological samples (e.g., epithelial tissues) is described herein, including a multispectral frequency-domain time-resolved fluorescence measuring system comprising a frequency-modulated continuous wave digital-pulse modulated diode laser (FM CW laser) and a light emission detector. The FM CW laser is configured for simultaneous multiwavelength excitation of a compound. The light emission detector is configured for simultaneous multispectral time-resolved fluorescence measurement of a fluorescence frequency response (FFR) of the compound. The compound may be in an epithelial tissue. The excitation is modulated at frequencies within a frequency range of less than 100 MHz. The FM CW laser may be configured to emit modulated excitation spanning a set of frequencies which comprises at least three different frequencies in a range between 1 to 99 MHz, the set comprising at least one frequency <50 MHz, and at least one frequency ?50 MHz and <100 MHz.