An apparatus and method of performing physical property measurements on a sample with a probe-based metrology instrument employing a nano-confined light source is provided. In one embodiment, an SPM probe tip is configured to support an appropriate receiving element so as to provide a nano-localized light source that is able to efficiently and locally excite the sample on the nanoscale. Preferably, the separation between the tip apex and the sample during spectroscopic measurements is maintained at less than 10 nm, for example, using an AFM TR Mode control scheme.