{"id":4018,"date":"2017-08-14T18:29:51","date_gmt":"2017-08-15T01:29:51","guid":{"rendered":"https:\/\/www.vernier.com\/til\/4018"},"modified":"2024-09-17T08:23:05","modified_gmt":"2024-09-17T15:23:05","slug":"4018","status":"publish","type":"post","link":"https:\/\/www.vernier.com\/til\/4018","title":{"rendered":"What does the UV sensor in my Go Direct Light and Color sensor measure?"},"content":{"rendered":"

There have been multiple versions of the UV sensing element in the Go Direct®<\/sup> Light and Color Sensor<\/a> (GDX-LC<\/nobr>).<\/p>\n

\n\n\n\n\n\n\n
Year released<\/td>\nLabel on the Go Direct®<\/sup> Light and Color Sensor<\/a> (GDX-LC<\/nobr>)<\/td>\nHalf-sensitivity range (nm)<\/td>\nNotes<\/td>\n<\/tr>\n
2017<\/td>\nUVA\/UVB or UVA (changed in 2020)<\/td>\n320 – 375<\/td>\nBoth labels have the same UV sensor. Relative scale.<\/td>\n<\/tr>\n
2022<\/td>\nUV-BLUE<\/td>\n300 – 425<\/td>\nNon-zero response to deep blue visible light. Relative scale.<\/td>\n<\/tr>\n
2024<\/td>\nUVB<\/td>\n260 – 315<\/td>\nFirst version with units identified in software (mW\/cm\u00b2)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>
Timeline of UV sensor changes.<\/figcaption><\/figure>\n
\"\"<\/figure>\n

All three versions report values in units of mW\/cm\u00b2. However, the unit released in 2024 is the first sensor version to report these units. Because of differing responsivity curves of these sensors, and the range covered, UV readings from different hardware releases cannot be directly compared. In each case the calibration is for the peak wavelength sensitivity, and readings for other wavelengths will be reduced per the responsivity curve. <\/p>\n

The calibration of the 2024 UVB sensor was tied to the UV Index based on the sensor specification sheet. The UV sensor reading can be converted to an approximation of the UV Index by multiplying the value by 50.71. The specifications are found in the attached document – in particular in the graphs below the Characteristics Table.<\/p>\n