Light source device with fly-eye integrator

A light source device with fly-eye integrator comprising:

• a plurality of light emitting elements;
• a collimating optical system that includes a plurality of lens regions each disposed corresponding to each of the plurality of light emitting elements at a subsequent stage of the plurality of light emitting elements and collimates light from a front focus of the lens regions;
• a condensing optical system that condenses light emitted from the collimating optical system;
• and
• a fly eye lens on which the light emitted from the condensing optical system is incident, wherein,
• it is defined that a focal length of the condensing optical system is f, a width orthogonal to an optical axis and having a maximum width of the collimating optical system is b, an axis coinciding with a line segment constituting the width b is an axis B, a width of a projection image on an axis optically equivalent to the axis B is a, the projection image being on a light emitting surface on a back focus surface of the condensing optical system, and a separation distance between an incident surface of the fly eye lens and a back focus of the condensing optical system is L, the light source device satisfies the following Formula (1)
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