8.8.1 Optical property of colloids (3)Ultramicroscope Fig. 2. Immersion ultramicroscope L= Light source: F= Telescope objective which gives a picture of the light source on the precision slit PrSp. The condenser B forms an image of the precision slit in the col- lodal solution, which is in a small The pictures reproduced from the Nobel Prize report 1): Particle size: For particles less than 0. 1 um in diameter which are too small to be truly resolved by the light microscope, under the ultramicroscope, they look like stars in the dark sky1): Particle size：For particles less than 0.1 m in diameter which are too small to be truly resolved by the light microscope, under the ultramicroscope, they look like stars in the dark sky. The pictures reproduced from the Nobel Prize report. (3) Ultramicroscope 8.8.1 Optical property of colloids