A scanning tunable detection system and related method for analyzing samples includes a source of time varying excitation signals and a tunable optical filter for selectively transmitting time-varying optical signals emanated from a sample following irradiation with the time varying excitation signals. A detector is provided for converting the time-varying optical signals to electrical detection signals. The system can identify components in a sample using phase sensitive or time sensitive detection. A slew scan mode can be used to permit slow scanning through spectral regions rich in information but quickly in regions without such information.