| 摘要 |
PURPOSE:To make exact measurement of the plating thickness in an extremely small part by providing plural collimator rolls having diameters different from each other to a collimator body and making the collimator body rotatable to change the diameter of the collimator holes thereby changing the beam diameter of X-rays. CONSTITUTION:A collimator body 36 having plural collimator holes 31-35 which are respectively different in diameter is pivotally supported freely rotatably by a pivotal supporting part 37 to the bottom end of a shutter body 19. Said collimator body is so arranged that when the body is rotated in the direction of an arrow B by a knob 38, the hole 33 matched with the position of a mark P acts as the collimator hole to be passed therethrough with an X-ray beam in this stage. The X-ray beam diameter is made changeable as desired by changing the diameter of the collimator holes with the above-mentioned constitution and therefore the plating thickness in an extremely small part is made measurable exactly. |
