2018 Volume 41 Pages 165-170
Recently, products of light emitting diodes (LEDs) are expanding in many areas, such as lighting and display technology. As well as luminous flux measurement in the lighting technology, luminance measurement is also important in the display technology. In this study, a transfer standard for LED luminance measurement, which based on a high-power LEDs and a homogeneous optic, was investigated by means of ray tracing simulation to make direct traceable chain from calibration laboratory to manufacturer. The transfer standard was modeled with homogeneous optics such as microlens arrays or light pipe, and the optical properties of two-type models were analyzed with ray tracing simulation. The ray tracing simulation results showed that the luminance difference in the transfer standard with microlens arrays achieves ±4% within 5 mm in diameter and the angular distribution of it close to Lambertian surface. The other, the luminance difference in the transfer standard with a light pipe achieves ±5% within 5 mm in diameter. Two types of the transfer standard are not inferior in luminance uniformity and diffused property to common transfer standard such as a tungsten ribbon lamp in the ray tracing simulation results, and then it is worth examining as candidates of a transfer standard for disseminating of luminance scale.