Development Of Luminance Coefficient Measurement System Base On Gonioreflecto-metry And Integrating Hemisphere Method

A good knowledge of the reflection properties of road surfaces allows more efficient designing of road lighting installations. This helps to optimize the visibility of objects on the road and thus promote driver safety while minimizing energy consumption.This paper presents a two-dimensional gonioreflectometer to measure luminance coefficient of the road surface. It uses tungsten lamp, LED lamp, etc. as the light source. Two motors drive rotation of two axes for the light source to scan centered on the sample surface in vertical and horizontal plane respectively, which provide two rotational degrees of freedom necessary to measure the road sample. The angular accuracy of the light source position machine is0.05°. The process is control by the computer system including operation, data acquisition, and data processing.A series samples are measured under different kinds of light source and results were compared and analyzed.We also describe a portable instrument that measures the average luminance coefficient of a road surface, Q0, in the field. The design employs a modified integrating hemisphere with light-emitting diode (LED) lamps as light sources and a calibrated charge-coupled device (CCD) luminance meter with an observation angle of1°as the detector. We proved the concept of instrument and calibrated the instrument by comparing its measurement results with those of a gonioreflectometer for a series of samples having different reflectance values. The performance characteristics of the instrument are appropriate for in situ Q0measurement.