We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk refractive index measurement of scattering and soft samples, not relying on surface measurements that can be prone to error. Our technique is also noncontact and compatible with in situ refractive index measurements. Here, we demonstrate this new technique on a pure silica test piece and a highly scattering resin slab, comparing the results with standard critical angle refractometry.
Original Manuscript: August 5, 2008
Manuscript Accepted: August 26, 2008
Published: September 30, 2008
Vol. 3, Iss. 12 Virtual Journal for Biomedical Optics
Peter H. Tomlins, Peter Woolliams, Christian Hart, Andrew Beaumont, and Matthew Tedaldi, "Optical coherence refractometry," Opt. Lett. 33, 2272-2274 (2008)