| 摘要 |
PURPOSE:To attain small size and light weight even when an objective lens whose focal distance is long is employed by turning a parallel plane plate at an angle proportional to a fluctuation of an attitude angle around a rotary shaft in parallel with an incident face of the parallel plane plate so as to correct the fluctuation. CONSTITUTION:A parallel plane plate 10 made of an optical transparent material is provided between an objective lens 1 and a photodetector and the parallel plane plate 10 is turned around a rotary shaft 11 in parallel with an incident face of the parallel plane plate 10 at an angle proportional to a fluctuation of an attitude angle to correct the fluctuation. In this case, the angle of the parallel plane plate 10 is set to a prescribed angle to correct a visual field angle when it is fluctuated. Furthermore, the rotary shaft 11 of the parallel plane plate 10 is one and two-axis fluctuation in an azimuth and elevation directions is corrected practically by providing another rotary shaft orthogonal to the rotary shaft 11 and an optical axis. |
