| 摘要 |
PURPOSE:To provided the lighting device which obtains an almost uniform luminous flux distribution in the surface direction and easily realizes optional distribution density. CONSTITUTION:This device has a light source means which outputs a nearly parallel light beam and a reflection part 24 where Fresnel elements each consisting of a nearly 45 deg. reflecting surface 24a which reflects the nearly parallel light beam and an ineffective surface 24b which is parallel to the optical axis of the nearly parallel light beam are formed successively into a linear Fresnel type. The reference surface on the back of the Fresnel elements of the reflection part 24 is expressed as y=kintegral F(x)/L(y).dx on two-dimensional (x, y) coordinates, where F(x) is the density distribution of the nearly parallel light beam flux from the light source means, L(y) is the density distribution of the luminous flux of reflected light, and (k) is a coefficient. |
