小径管一次成像透照及底片评判

The oneshot ray Photograph of small Radius Pipe and Evaluation of Negatives

小径管一次成像双壁双影法透照时，由于射源侧焊缝比胶片侧焊缝离开胶片的距离相差一个管子的直径。因此，射源尺寸和几何布置的影响会使射源侧影像放大，影像的放大必然会影响到底片评级。通过分析影像放大因素，提出了应参照管子壁厚和缺陷影像大小来综合评定，确定缺陷的实际大小，以便正确评判底片。

In the application of one shot doublewall /doublepicture ray photograph in the detection of small radius pipes,the effect of the source size and its geometry will amplify the picture on the side of the source as the distance between the film and the film side weld is a radius longer than that between the film and the source side weld. The amplification of the source side picture will disturb the evaluation of the negative. In this paper the factors affecting foe picture amplification are analyzed,Based on the analysis,the author proposeses a method to determine fault size by considering the wall depth and the fault picture size as to evaluate negative photography correctly.