A method of high-speed processing and monitoring of a product, such as a pharmaceutical powder or tablet, comprises: moving the product (C) past an inspection station; illuminating at least a portion of the product with light; spectrally filtering a first portion of light carrying information about the product, o.g., transmitted or reflected light, by passing said first portion through at least one multivariate optical element (148) and detecting said filtered light with a first detector (152), —detecting a deflected second portion of said light with a second detector (156); and determining at least one selected property of the product based on the detector outputs.