Koichi Takase, Norimichi Tsumura, Toshiya Nakaguchi and Yoichi Miyake
Department of Information and Image Sciences,
Chiba University 1-33, Yayoi-cho, Inage-ku,
Chiba 263-8522, Japan
OPTICAL REVIEW Vol.13, No.5, pp.314-319(2006).
Abstract
This paper presents a method of measuring a light field of a light source
with high directional resolution using a mirrored ball and a pinhole camera.
The light field describes a spatial and directional distribution of radiances
from the light source. The directional distribution is expanded by a reflection
on the mirrored ball, and the radiances are measured by a charge-coupled
device (CCD) camera with a pinhole lens. The light source is laterally
moved by a robot arm to measure the directionally expanded light field,
and each pixel on a CCD can obtain the radiances from the light source
through the pinhole lens with high directional resolution. The light field
is estimated from the pixel value and the position of each pixel using
a ray tracing technique. The light field of a krypton lamp was experimentally
measured by the proposed method, and the accuracy of the measurement was
evaluated against the irradiances measured by a spectro-radiometer at sample
points.
Full paper ( to appear )
[PDF][PDF_figures]