Measuring light-emitting diodes with a scanner for radiant flux and colour characterization

Due to the performance requirements of displays and lighting applications, there is a great need to measure the radiant flux and colour of light-emitting diodes (LEDs) simultaneously in a high throughput format. We evaluate the feasibility of obtaining reliable colour and radiant flux values of LEDs with a low-cost office flatbed document scanner under factory settings versus conventional measurements. Colour purity was evaluated against a spectrometer and a digital camera, while radiant flux was evaluated against photodiodes. Scanner colour rendition of red, green and yellow LEDs was of variable quality. The scanner showed better correlation to conventional radiant flux measurements, with linear least-squares agreement between 0.934 and 0.985. A scanner represents a low cost and high throughput means of evaluating LEDs with simultaneous measures of both electroluminescent flux and emission colour with operational time.