critical maximum meaning in English

临界极大值
临界最大值

The numerical results show that the appearance of focal switch rests not only on the distance of aperture and lens but also on truncation parameter ; focal switch possibly occurs only when truncation parameter is between its critical maximum and minimum truncation parameters
数值结果表明：焦开关的出现不仅与光阑透镜分离量有关，还与截断参数值密切相关；仅当截断参数取某一上、下限之间的值时，才可能出现焦开关。