扫描式超高速摄影中转镜镜面变形量的几何补偿

利用三维有限元计算技术,分析了从三面体到八面体铝合金转镜镜面变形规律.发现以四面体为界,三面体转镜镜面变形为向内凹进,五面体及以上转镜镜面则向外凸出.在对镜面变形定量分析基础上,提出了镜面变形的几何补偿方法,即采用柱面代替平直镜面,使镜面变形后的位置趋近于平直.结果表明,对镜面尺寸17.32 mm,轴向长度32.5 mm的三面体铝合金转镜,在5×104 rpm下,镜面最高点偏离平直镜面的最大值为0.468 μm,是平直镜面的1/9,与相同结构尺寸的铍转镜镜面变形量处于相同量级.说明铝合金转镜采用几何补偿方法,可以在扫描式摄影系统中代替铍转镜.

Advance Deforming Mirror Faces of Rotating Mirror for Streak Camera

The elastic deformations of mirror surfaces from three-faced to eight-faced rotating aluminous mirrors were analyzed by 3-D FEM. The results indicates that the deformation patterns of all mirrors in operation can be distinguished into three kinds: the surface of three-faced mirror is retuse, the surface of four-faced mirror looks like a saddle, and the shapes of whole surface express crowning outward for five, six, seven and eight-faced mirrors. The method of advance deformation for mirror faces was brought up on the basis of quantificational analysis: the even mirror faces are replaced with cylindrical surface so that the faces in operation can be flattened up. The results show that the relative departure magnitude between vertex of surface and even surface is 0.468 μm which is 1/9 times of even surface deformation magnitude for the mirror that mirror surface is 17.32 mm width and 32.5 mm length, and the rotate speed is 5×104 rpm, and that the even surface of beryllium mirror is approximately 0.17 μm of deformation magnitude. So the aluminous mirror that its surfaces are cylindrical can replaces Be mirror.