| 摘要 |
PURPOSE:To facilitate adjustment of an illumination system for low-magnification objective lens by constituting a condenser lens consisting of the three groups, a positive lens group, a negative lens group and a positive lens group, and an aperture diaphragm in one body. CONSTITUTION:A light source 20, a collector lens 21 of which the front side focus is roughly aligned to the light source 20, a field stop 22 which is disposed near the rear side focus of the collector lens 21, a window lens 23 of which the front side focus is roughly aligned to the field stop 22, a condenser lens 24 of the 3-group constitution consisting of a positive lens group L1, a negative lens group L2 and a positive lens group L3, and an aperture diaphragm 25 which is disposed near the front side focus of the positive lens group L3 between the negative lens group L2 and the positive lens group L3 are disposed successively on the optical axis, and the collector lens 21 and the window lens 23 as well as the window lens 23 and the condenser lens 24 constitute afocal systems respectively, whereby the Ko hler's illumination system for low magnifications including extra low magnifications is realized. |
