| 摘要 |
PURPOSE:To correct elevation angle irrelevant to the inclination of the machine by vertically suspending a roof prism and the frame body thereof slightly separated from the elevation scale plate to ensure that the scale invariably exists on the axis of the optical system. CONSTITUTION:A roof prism 2 and a frame body thereof 2 are vertically suspended with a suspension line 4 at a suspension point 7, namely, one-half the radius R of the elevation division scale 5. As the machine tilts by alpha, the roof prism 2 deviates by alpha.R/2 horizontally and then, rests. At this point, the reflection surface of the roof prism covering scale images moves to the point 0' whereby the scale is automatically corrected to ensure that it invariably exists on the axis of the optical system. |
