七十五年是一段相当长的时间,和多数人的寿命差不多,而美国光学工业经历的时间则更长。早在十九世纪八十年代,美国光学器件的制作技术开始有了显著的进步。包括麻萨诸塞州的Clark兄弟制成用在望远镜上的大型折射 The seventy-five years is a long period of time, and the life expectancy of most people is almost the same, while the American optical industry has experienced a longer period of time. As early as the 1880s, the United States began to make significant advances in the production of optical devices. Large-scale refraction made on the telescope made by Clark Brothers including Massachusetts