A direct-view optical microscope system is provided which uses high-energy light from a phenomenon known as non-resonant Raman-scattering to illuminate a biological specimen. One embodiment of the system combines two discrete light sources to form a combined incident light source for the microscope. The system includes a method and apparatus for modulating the intensity of the scattered light when two light waves are combined to produce the incident light. By varying the frequency of the two source light waves, the intensity of the combined Raman-scattered light can be modulated to achieve finer resolution. In one embodiment, the system provides illumination and observation of microscopic agglutination events between pathogenic antigens and specific antibodies, for prompt detection and identification in the field.