| 摘要 |
<p>For use with an optical scanning device, a reading head (40) comprising a housing (41, 83) having at least one bore (42, 84, 84') for accommodating therein a respective photo-multiplier tube (43, 81, 82) and a non-intersecting lateral bore (44, 85) for accommodating therein a stimulating light source (45, 86) for producing a stimulating beam having a first wavelength. A focusing lens (46, 91) is mounted in association with the stimulating light source for focusing the stimulating beam on a film (92) of the scanning device so as to produce stimulated fluorescent light having a second wavelength in the film at a point of contact by the stimulating beam. A window (50, 88) is provided within the housing for mounting therein a filter (51, 89, 90) for transmitting therethrough the stimulated fluorescent light whilst substantially blocking reflections of the stimulating beam. The housing is mounted in spaced relationship with the film so as to direct the stimulating light beam perpendicular to the film such that the distance from the film to an internal periphery of the lateral bore within the housing is equal to a focal length of the focusing lens, and the stimulating light source is fixed within the lateral bore so that the focusing lens is in precise registration with the internal periphery.</p> |
