A diffuse reflectance spectroscopy system for determining an optical property of a specimen and a method for operating the same are provided. The system includes: a light emitting unit comprising a light emitting terminal, the light emitting unit configured to emit steady light； an optical medium arranged at one end of the device, the optical medium being controllable to switch between multiple optical states and configured to deliver the steady light to the specimen through the optical medium in different optical states, wherein the optical medium comprises a first surface in contact with the light emitting terminal of the light emitting unit and a second surface for contact with the specimen； and a detecting module comprising one or more receiving terminals for receiving light scattered from the specimen for determining the optical property of the specimen.
