Optical bandpass filters ‘enable imaging of viscous materials’

Optical bandpass filters can allow static and dynamic imaging of viscous materials using a technique similar to that already used in the detection of some cancers, according to researchers.

Early detection of abnormalities

Tissue abnormalities such as malignant lymph nodes in the breast can be detected using optical bandpass filters to create three views of the tissue at different wavelengths.

All of these views are then combined into a single three-dimensional image for analysis – and researchers writing in Review of Scientific Instruments say the same can be done on viscous materials.

“Independent images are obtained by two beam splitters which are connected in series,” they explain. “Based on these images, it is possible to evaluate each image separately.

“In our case, three optical bandpass filters with different centre wavelengths of 405 nm, 420 nm, and 440 nm were used to filter the separate fluorescence images.”

These images can then be used to examine the material for impurities, incorrect mixing ratios and wrong single components.

Versatile applications

Unlike in medical applications, the researchers found the technique can work for dynamic views as well as static substances – allowing viscous flows of up to 0.2 m/s to be imaged directly.

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