optical aid

• 视觉辅助器,光学辅助工具

optical aid的用法和样例：

例句

1. Given the surviving records for all manner of other optical systems and mechanical drawing aids, the absence of evidence for the Hockney projector is difficult to explain.
   其他光学系统与绘图辅助工具的记录，到今天都还留存了不少，为何唯独缺乏霍克尼投影设备的证据，显然很难解释。