A diagnostic system includes a light source having semiconductor sources, optical amplifiers, and fibers configured to deliver a first optical beam to a nonlinear element configured to broaden a spectrum of the first optical beam to at least 10 nanometers through a nonlinear effect in the nonlinear element, wherein a broadened-spectrum output beam comprises a near-infrared wavelength between 600-1000 nanometers. An interface device, having a cap with fiber leads configured to couple to the light source and to a receiver having one or more detectors, delivers the output optical beam to a tissue sample. The receiver is configured to receive a diffuse spectroscopy output beam resulting from light diffusion of the output optical beam into a top two (2) millimeters of the sample and to process the diffuse spectroscopy output beam to generate an output signal that monitors absorption or scattering features of the tissue sample.
