Measuring the optical properties of natural silks

There is an emerging interest in natural silks as an optical material due to their attractive optical and mechanical properties, potential to engineer their properties by modifying their protein structure and relative ease with which natural silk can be obtained. There a need to develop accessible new optical characterisation techniques that can be applied to these challenging samples. Here, we present a new technique capable of measuring the optical properties of silks that requires only a standard laboratory microscope with a digital camera and a series of traceable refractive-index liquids. This method was used to obtain the first optical absorption measurements of spider silk. Measurement of other optical properties such as birefringence and dispersion will also be presented.