Optical inspection system and radiation source for use therein

Disclosed is a system for inspecting an object. Such system comprises; a) an irradiation system for irradiating the object to be inspected, said irradiation system comprising a radiation source, b) an objective, imaging the irradiated object onto an image sensor, and c) an image sensor for transforming the radiation coming from the object to be inspected into a detectable signal. The radiation source comprises; A) at least one cathode, B) at least one anode, C) one or more plates, positioned in between said cathode(s) and said anode(s), and being electrically substantially insulated, wherein each plate comprises at least one hole, aligned in such a way that a continuous path is created between cathode and anode over which a discharge can extend.