| 摘要 |
PURPOSE:To scan laser ight which has different wavelength through one ftheta lens by composing the lens of a front group of a negative lens and a rear group of three positive, positive, and negative lenses successively from an entrance pupil, and satisfying specific requirements. CONSTITUTION:This lens system consists of four elements in two groups, i.e. the front group of the 1st negative lens and the rear group of the 2nd positive lens, the 3rd positive lens, and the 4th negative lens in order from the entrance pupil, and is the ftheta lens system which meets requirements shown by inequalities I -III. In the inequalities, (f) is the composite focal length of the whole system and nui the Abbe number of the (i)th lens; and ni is the refractive index of the (i)th lens and d2 is the on-axis air interval between the 1st and the 2nd lenses. |
