A system for analyzing a tissue sample includes two wavelength-division multiplexers and a fiber coupler. The first wavelength-division multiplexer combines visible and near infrared electromagnetic radiation and directs the combined electromagnetic radiation to the fiber coupler. The fiber coupler emits a sample beam of visible and near infrared electromagnetic radiation toward a tissue sample, and a reference beam of visible and near infrared electromagnetic radiation toward a reference mirror. The sample beam reflects off the tissue sample back to the fiber coupler. The reference beam reflects off the reference mirror back to the fiber coupler. The fiber coupler combines the reflected sample and reference beams and directs the combined electromagnetic radiation to the second wavelength-division multiplexer. The second wavelength-division multiplexer sends visible electromagnetic radiation from the sample and reference beams to a first spectrometer, and near infrared electromagnetic radiation from the sample and reference beams to a second spectrometer.