| 摘要 |
A measuring apparatus (10) for measuring the thickness of a coating on a workpiece (36) by X-ray fluorescence. The apparatus includes a frame (12) upon which is mounted an X-ray tube (14), a shutter (16), first collimator means (18), and a mirror (20) through which an X-ray beam may be projected. Also mounted on the frame (12) is a signal detector (26), which may be in the form of a proportional counter, a fixed focal length viewing device (28) which is capable of viewing a workpiece through the mirror, and a work holder (34) carried by a work holder mount (32) which is capable of moving the workpiece (36) in x, y and z orientations. The apparatus is further provided with a second collimator means (48) shiftable by a moving apparatus (53) from an inoperative position to an operative position wherein a second collimator (50) is disposed between the mirror and the workpiece in such a manner that the terminal end (51) of the second collimator is as close as possible to the coating on the workpiece. In one embodiment there is only a single fixed first collimator and a single movably mounted second collimator. In a second embodiment there are a plurality of indexable first collimators, and a fewer number of second collimators, each second collimator being mounted in alignment with an associated first collimator.
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