The sensor measures global solar UV irradiance, the sum of the components of solar UV transmitted directly and those scattered in the atmosphere. Scattered UV is a major portion of global irradiance. The transducer is a semiconductor photodiode that responds only to radiation in the region of interest. The diffuser provides an excellent cosine response. With multiple hard-oxide coatings, the interference filter provides the Erythema Action spectral response. It is stable in the presence of heat and humidity. The outer shell shields the sensor from thermal radiation and provides a path for convection cooling of the body, minimising heating of the sensor interior. It provides a cutoff ring for cosine response, a level indicator, and fins to aid in aligning the sensor with the suns rays. Spring-loaded mounting screws, in conjunction with the level indicator, enable rapid and accurate levelling of the sensor. Each sensor is calibrated against a Yankee Environmental Systems Ultraviolet Pyrometer, model UVB-1, in natural summer daylight. Davis Universal bracket for pole mounting (part 6670) or Solar/UV Mounting shelf for ISS mounting (part 6673) required for installation.
![Davis UV Sensor [6490]](https://cdn.shopify.com/s/files/1/0691/3376/2863/products/52166XL.jpg?v=1674847376&width=480)
![Davis UV Sensor [6490]](https://cdn.shopify.com/s/files/1/1899/9737/products/52166XL.jpg?v=1762961463&width=480)
![Davis UV Sensor [6490]](https://cdn.shopify.com/s/files/1/0065/7349/0245/products/52166XL.jpg?v=1680077624&width=480)