| 摘要 |
The specification describes an irradiation device, more particularly for use for causing the polymerization of fillings of resins in dentistry, using radiation in the UVA range which is transmitted from a radiation source via a light guide. The source of UVA radiation is a tungsten incandescent filament lamp with a color temperature of at least 3150 DEG K. and an electrical power of at least 15 Watts. For a defined solid angle, which is not less than 6 sterad, the radiation from the filament of the lamp is collected by an UV reflecting reflector and focussed at a focal point F1 lying outside the incandescent filament lamp. In the ray path between the filament of the lamp and the focal point F1 a dielectric thin film reflection filter is provided with a defined angle alpha of inclination NOTEQUAL 0 DEG of the filter normal to the optic axis defined by the incandescent filament and the focal point F1. This thin film filter has a maximum reflection capacity for radiation which is incident at the angle alpha to the filter normal in a wavelength range between 330 nm and 400 nm. The reflecting thin film filter produces a second focal point F2 which lies outside the optic axis as mentioned above and is substantially less intensive with respect to the radiation power density. This second, less intensive focal point comprises a comparatively high fraction of UVA radiation. The radiation collected at the point F2 is subjected to further optical filtration to remove undesired visible and infrared radiation either by reflecting thin film filters or by absorption filters or by the internal filter action of the light guide employed. The UVA radiation which converges at the second point F2 is collected by a light guide whose effective numerical aperture is larger than 0.34.
|
