Fast and compact scatterometer for ex vivo qualification of low-scattering biological samples.

We present the design, calibration, qualification, and application of a fast and compact scatterometer designed for the characterization of ex vivo human corneas. As an alternative to standard qualification processes and in order to meet the current need for improved reliability of graft qualification, this instrument provides a non-invasive, label-free, and contact-free quantitative means of characterizing corneal grafts, based on back-scattered light diffusometry. The instrument is shown to be capable of detecting BRDF (bidirectional reflectance distribution function) variations of 1.4 × 10-4 sr-1 with a detectivity threshold of 2.0 × 10-3 sr-1, with an overall dynamics >27 dB for the total integrated scattering parameter used for graft quality assessment. We also demonstrate the feasibility of integrating this new technique into tissue bank qualification processes through controlled test experiments reported here.