| 摘要 |
A lighting device with variable angle of emission includes a light source, and a lens system comprising two lenses, a primary lens and a secondary lens. The two lenses and the light source are arranged along an optical axis and the distance between the primary lens and the secondary lens is variable, in order to vary the angle of emission of the cone of light rays generated by the lighting device. In one example, the primary lens has a numerical aperture of at least 0.7, the primary lens is an aplanat, and the secondary lens is designed so as to image to infinity, at a certain distance of the secondary lens from the primary lens, a virtual image of the light source generated by the primary lens. According to a second aspect, the illumination factors are distinguished by the fact that the primary lens has a numerical aperture of at least 0.7, and that the secondary lens may be moved by a distance extending in a range in which the secondary lens does not capture the whole of the cone of light rays generated by the primary lens.
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