A novel and simple noninvasive sensor techniquefor simultaneous measurement of refractinve-index and thickness of both optically transparent and non-transparent media is presented. It is a fiber-optic confocal-microscope-type sensor technique based on either a single-confocal or a combined dual-confocal fiber-optic design. The single-confocal design is a single-fiber, intensity sensing arrangement that provides precise spatial location of the backreflecting sample surfaces and bi-parameter measurements. The combined dual-confocal design includes two independent confocal channels consisting of two identical apertureless fiber-optic-type confocal microscopes constructed by use of a single 2×2 fiber coupler. This sensor arrangement provides direct measurement in absolute unites of refractive-index and thickness of optically transparent and non-transparent media.