A Novel Method of Bending Crystals to Log Spiral Shape

Crystals bent to logarithmic spirals have been used in applications where large acceptance of divergent x-rays from a small source is needed [1]. Small acceptances can be easily handled with cylindrically bent crystal. In cases where larger acceptances are needed differential bending may be adequate [2]. However, the largest acceptance is obtained from a flat crystal plate when bent into the logarithmic spiral shape that allows the crystal to present the same angle of incidence to the beam emanating from a point source. The bending of such crystals generally can be accomplished by forcing the crystal into the required shape with a metal frame [3].