本文研究虚前焦面目镜,它的光学系统包括在虚前焦面前的负聚光镜和在负聚光镜后面的正光力透镜组。并称后者为“眼部”。这种目镜与具有实前焦面和正焦距值的目镜有本质区别:前者中的某些几乎可以完全校正场曲,因为它的象差系数S_Ⅳ接近于零,且大多数是个很小正值,但也有S_Ⅳ很大负值的。它的球差不仅有负的,而且也有正的和接 In this paper, the virtual front focal plane eyepiece is studied. Its optical system consists of a negative condenser in front of the imaginary front and a positive power lens in the back of the negative condenser. And said the latter is “eye.” This eyepiece is essentially different from an eyepiece with a real focal and positive focal length: some of the former can almost completely correct field curvature because its aberration coefficient, S_IV, approaches zero and most of it is a small positive value, But there are also S_IV very negative. It’s bad not only negative, but also positive and then