This application discloses a lens system comprising in order from an object side to an image side: an aperture stop; a first lens element, having a positive optical power; and a second lens element, having a negative optical power. By setting the shapes of the respective lens elements and the materials making up the respective lens elements so as to meet predetermined conditions in such a lens system, a lens system of a compact size which provides good optical performance is realized while securing telecentric characteristics.

 
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< Solid immersion lens and sample observation method using it

< Liquid-immersion objective optical system

> Immersion microscope objective lens

> Three-group zoom lens

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