Harwell Dosimeters produces high-quality dosimeters mainly for use in the sterilisation of medical devices. Two types – Red 4034 and Amber 3042 – are made from radiation-sensitive poly-methylmethacrylate (pmma) in the form of optically transparent pieces individually sealed in laminate sachets. They darken when irradiated, and the radiation-induced darkening, accurately measurable by means of a spectrophotometer, is a function of the radiation dose absorbed. We maintain a page providing technical specification for each product.