National Physical Laboratory

Spectral irradiance standard Optical Radiation & Photonics

NPL's optical radiation scientists provide a wide range of measurements for characterising sources and detectors and the properties of materials, covering the ultraviolet, visible and infrared regions.


NPL’s activity in this area underpins optical radiation and photonic measurements across a wide range of applications. In industrial sectors such as colour processing, food, transport,  pharmaceuticals, lighting, digital film production, communications, medical imaging and solar cells, for example, these measurements support essential activities such as product development, quality assurance, health and safety and compliance with regulations.

Optical radiation measurements are also critical for understanding climate change: e.g. by providing traceability for Earth Observation (EO) satellites and for systems for monitoring changes in solar irradiance levels at the Earth’s surface, they allow researchers to make improvements to climate models and to understand better the disagreements between different models and data sets. NPL’s scientists are leading international activities to improve the quality and reliability of EO data and are developing new measurement techniques and instrumentation to reduce the associated measurement uncertainties.

Optical radiation has many effects on humans, plants and animals, both beneficial and detrimental. Thus optical radiation measurements are often based not only on physical parameters, but also take account of associated photobiological responses such as human vision, the potential damage to eyes and skin caused by high levels of UV or IR radiation, and the relationship between light, sleep-wake cycles and physical and mental health and well-being. NPL’s optical radiation team is working to support researchers investigating these photobiological influences, as well as developing new measurement capabilities, such as facilities for characterising the appearance of textured and patterned materials and systems for evaluating changes in the visual effectiveness of lighting under twilight conditions.

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