光学计是一种用于长度测量的精密光学仪器。它诞生于本世纪初,但目前在生产中的应用仍然十分广泛。我国有关这一仪器工作原理的叙述及其光学传动比的推导,大都转引自苏联教授阿派林所著“公差和技术测量”一书。大家知道,它是把光学计管的原理用图1和图2两个相互垂直平面内的光学现象来解释的,并在此基础上求得了传动比公式。由于该书在 Optics is a precision optical instrument used for length measurement. It was born at the beginning of this century, but its application in production is still very extensive. The narration about the working principle of this instrument and the derivation of its optical transmission ratio in our country are mostly quoted from the book “Measurement of Tolerance and Technology” issued by Professor Aplin of Soviet Union. We all know that it is the principle of the optical tube with Figure 1 and Figure 2, two mutually perpendicular optical plane to explain the phenomenon, and on this basis obtained the formula of the transmission ratio. Because of the book in