| 摘要 |
A zoom device for a lighting fixture has a first lens assembly of positive refractive power; a second lens assembly of negative refractive power; and a third lens assembly of positive refractive power. The first lens assembly, second lens assembly, and third lens assembly are aligned along a longitudinal axis coincident with the axis of a light beam emitted by a light source of the lighting fixture, and are characterized by respective focal lengths, which are such as to effectively adjust the size of the images projected by the lighting fixture, while at the same time maintaining compactness of the zoom device. |
