Low coherence interferometry for simultaneous measurement of refractive index and thickness

Low coherence interferometry has been used for optical ranging with an accuracy comparable to the coherence length of the light source of the interferometer. This technique has been extended to optical imaging for clinical diagnosis. Very recently, we developed a practical interferometer system which allowed us to measure automatically the refractive index (n) and thickness (t) in a wide thickness range of 20 /spl mu/m to a few mm. This low coherence interferometer is shown. The light source is a superluminescent diode (SLD) having a coherence length 12 /spl mu/m at the center wavelength of 850 nm. The developed system will be widely used in practice for precise measurement or monitoring of index and thickness of all optical materials including crystals, glass, polymer, epoxy, and so on. In addition, our method is applicable for determination of the refractive index and geometric dimension of biological tissue.