A method and system that enable the measurement of a second-harmonic-generation-forward/backward (SHG F/B) ratio from an object by performing only a single image scan using via epi-imaging using an epi-detection technique. Two simultaneous SGH images (a forward propagating SHG “F” image and a back propagating SHG “B” image) are generated during the single image scan. A pinhole mirror can be used to separate the F-SHG and the B-SHG, which are detected by separate detectors.
