SYSTEMS AND METHODS PROVIDING EFFICIENT DETECTION OF BACK-SCATTERED ILLUMINATION IN MODULATION TRANSFER MICROSCOPY OR MICRO-SPECTROSCOPY

摘要

A microscopy or micro-spectroscopy system is disclosed that includes a first light source, a second light source, a modulator, an optical assembly and a processor. The first light source is for providing a first illumination field at a first optical frequency ?1 and the second light source is for providing a second illumination field at a second optical frequency ?2. The modulator is for modulating a property of the second illumination field at a modulation frequency f of at least 100 kHz to provide a modulated second illumination field. The optical assembly includes focusing optics and an optical detector system, The focusing optics is for directing and focusing the first illumination field and the modulated second illumination field through an objective lens toward the common focal volume along an excitation path. The optical detector system includes at least one optical detector for detecting a detected first field intensity of the first illumination field that is back- scattered within a sample, wherein the optical detector provides an electrical signal representative of the detected first field intensity. The optical detector is located proximate a portion of the excitation path. The processor is for detecting a modulation at the frequency f of the electrical signal due to non-linear optical interaction within the common focal volume.