To provide a multiplexer that makes it possible to achieve a reduction in size and that minimizes the influence of the expansion of laser light on a multiplexing unit. A multiplexer is provided with a plurality of waveguides, multiplexing units that are provided at an intermediate location within the waveguides, and laser light sources, wherein: the first multiplexing unit is arranged at a position that is closest to the laser light sources; and the laser light sources that have an optical axis at a position that is separated from the transmission axis of the visible light that is introduced into the first multiplexing unit are arranged so that the optical axis is inclined with respect to the transmission axis and the outer periphery of laser light that expands at a predetermined expansion angle passes in front of the first multiplexing unit.

An endoscope system has observation modes making observations with lights having optical characteristics different from each other. The system includes an endoscope including an insertion section provided with an illumination window, a light guide arranged in the insertion section, and including an entrance end on which the lights enter and a plurality of light guide areas that guide the lights entered on the entrance end, and an entrance area switching unit that switches between the light guide areas through which the entered lights are guided by switching between areas on which the lights enter at the entrance end in accordance with an observation mode.

The present application is directed to optical dispatching circuits that may reduce the footprint of an illumination system. In particular, embodiments of the present application provide an illumination system that splits and spreads incoming light sources (e.g., RGB laser light sources) into a plurality of emitters that cover a two-dimensional (2D) area. The present application describes various implementations of an optical dispatching circuit, which receives light as input and is configured to spread this light across a number of waveguides that each emit light from a plurality of locations. The optical dispatching circuits described herein may be configured to receive light from multiple sources emitting at different wavelengths (such as, but not limited to, red, green and blue light) and effectively deliver the light from the multiple sources in a substantially uniform manner to a plurality of emitters that cover a 2D area.