Patent ID: 7413430

Claim:
A pressing apparatus for forming a twin in a quartz crystal by the hot pressing method, comprising: a lower block consisting of a lower heater block and a lower pressing plate; an upper block consisting of an upper heater block and an upper pressing plate; and a bearing block connecting to the upper heater block of the upper block, wherein the lower block and the upper block function to hold the quartz crystal, the lower pressing plate and the upper pressing plate are constructed from a different material from the lower heater block and the upper heater block, a surface disposed so that it contacts with the quartz crystal during the hot pressing, on either the lower pressing plate or the upper pressing plate; said surface having a step structure with a plurality of periodic protruding parts satisfying quasi-phase matching condition for the quartz crystal and having the period from several microns to several tens of microns, the upper heater block has a protruding part which is worked into a convex surface with a radius of R 1 , the bearing block has a recessed part with is worked into a concave surface with a radius of R 2 (R 2 >R 1 ), and the protruding part and the recessed part are engaged to generate a swinging mechanism.