Abstract: According to various embodiments, a Raman spectroscopy method is provided for reduction of background fluorescence signal. The method may utilize a high speed optical chopper configured to periodically interrupt the laser light beam between the laser light source and the sample; and using the high speed optical chopper to provide a synchronized time-gated optical window for receiving mostly Raman signal while rejecting most or some of the fluorescence signal transmitted from the sample in response to the laser light beam before reaching the sensor.