| 摘要 |
PURPOSE:To make it possible to adjust the amount of exposure highly accurately by providing a filter wherein the film thickness at a point where an electromagnetic wave passes is changed by the movement of the filter, and moving the filter so that the measured value of the strength of the electromagnetic wave passing through the filter becomes a preset value. CONSTITUTION:When a filter 50 is rotated on a rotary axis, the film thickness of the filter 50 at a point where an electromagnetic wave 3 passes is changed. The strength of the electromagnetic wave passing through the filter 50 is measured with a measuring device 4. The measured value of the strength of the electromagnetic wave is compared with the preset value of an X-ray intensity setting device 100 in a comparing device 5. The signal of the comparison corresponding to the result of the comparison is generated. A rotating device 150 which has received the signal of comparison moves the filter 50 based on the signal of the comparison. The film thickness at the point where the electromagnetic wave passes is changed, and the electromagnetic wave which has passed through the filter 50 is attenuated. Thus, the amount of exposure can be adjusted accurately without replacing the filter 50 and without deteriorating throughput. |
