Patent ID: 8284485
Filing Date: 2012-10-09
Classification: G02B

Abstract:
1. An illumination optical system which irradiates a sample surface with light through an illuminating lens, comprising: a light source; a condensing optical system receiving the light emitted from the light source, wherein the condensing optical system is a collector lens; and a lens array optical system including a first lens array surface and a second lens array surface each formed by a plurality of lens elements; wherein: the first lens array surface has a conjugate relation with a focal position of the illuminating lens; the second lens array surface is placed at a back focal position of the lens array optical system and has a conjugate relation with a pupil position of the illuminating lens; the light source and the condensing optical system are arranged to form an image of the light source on the first lens array surface; and at least one of the light source and the collector lens functions as a switching unit for switching between a first illuminating state in which a plurality of images of the light source are formed on the second lens array surface and a second illuminating state in which an image of the light source is formed on the first lens array surface.