| 摘要 |
PURPOSE:To easily process and assemble an optical scanner and, at the same time, to make its ftheta lens system compact by constituting the ftheta lens system of three single lenses, of which the two lenses on the deflection-reflecting side are cylindrical lenses and the 3rd lens on the light emitting side is a toric lens. CONSTITUTION:Both of cylindrical lenses 41 and 42 have Y- and X-surface refracting powers on their incident and light emitting surfaces, respectively. Therefore, each of the cylindrical lenses and a toric lens on the light emitting side has refracting powers in both X- and Y-surface directions. As a result, a desired lens characteristic can be formed by combining the at least three or more refracting powers. Moreover, the cylindrical lenses 41 and 42 and toric lens 43 can be designed to have independent optional refracting powers on both X- and Y-surface directions by free designing. Therefore, the lens system can be made compact and can be assembled easily. |
