A scanning spectral-analysis micro-probe subsystem, for a surface imaging system, utilizes a micro-probe to detect the precise position of a point on a sample object surface having surface dimensions changing responsive to surface absorption of incident radiation from a modulated radiation source. The modulated incident radiation causes the sample region dimensions, in the vicinity of the micro-probe, to be modulated, so that the micro-probe detects this dimensional modulation, with a detected modulation strength directly proportional to the incident radiation absorption.