| 摘要 |
In the method, light from an ultraviolet light source is directed alternately through a neutral filter, uniformly damping the radiation of the light source, and through a partially absorbing filter damping only the wavelengths necessary to excite the fluorescence of a selected flourescent material, the partially absorbing light filter including the selected fluorescent material. The light passing through the filters is then directed through a first blocking filter onto a sample to be checked for the presence of a selected fluorescent material. Only the radiation from the sample is directed through a second blocking filter onto a photodetector or the like. The respective intensities of radiation of the sample, effected by the neutral filter and by the partially absorbent filter, are measured and converted into output signals indicative of the presence or absence of the selected fluorescent material. The two filters may be moved alternately into the path of the exciting beam from the light source, and the neutral filter may be either a wide band absorbing grey filter or a free opening for passage of the exciting beam from the light source. By using plural of such partially absorbing light filters, each damping only the wavelengths necessary to excite the fluorescence of a respective fluorescent material, it is possible to distinguish between several fluorescent materials which may be present in the sample. |
