| 摘要 |
An optical device directs light from a light source to a region of space, such as the field of view of a camera when the optical device is used as a camera flash unit. This device includes a first optical element which converges light from the light source towards an inner portion of the region to be illuminated and a second optical element which diverges part of the light from the first element outwardly towards an outer portion of the region to be illuminated so as to achieve adequate central illumination with improved uniformity of illumination across the region to be illuminated. The second optical element may have a concave multiple-faceted surface comprising plane facets in the shape of an open-base inverted truncated pyramid, contiguous sector-shaped facets, at least some of which are concave, or a face divided into an elongate portion disposed between first and second diverging portions. |
