Optical coherence refractometry.
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.
Tomlins
Peter H
PH
Biophotonics Group, National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK. pete.tomlins@npl.co.uk
Woolliams
Peter
P
Hart
Christian
C
Beaumont
Andrew
A
Tedaldi
Matthew
M
D046169:Dermoscopy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D012031:Refractometry / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012879:Skin Physiological Phenomena; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*