Reactor having an optimized lighting device

A reactor including a vessel for containing:

• a mass to be treated,
• at least one lighting device configured to promote the treatment of the mass, and
• a plurality of light diffusers, wherein two adjacent light diffusers in the plurality of light diffusers are spaced apart by a distance of between 2 and 10 centimeters,
• wherein each lighting device comprises:
• a light diffuser including at least one micro-etched plate transparent to light radiation and having opposite rear and front faces and at least two edges between the rear and front faces, wherein the area of each face is greater than an area of each edge, and wherein the rear face includes a plurality of micro-patterns, and a pitch between two adjacent micro-patterns of the plurality of micro-patterns of between 100 and 900 μm and greater than or equal to 100 μm, and
• a light source configured to generate the light radiation, wherein the light source is disposed on at least one edge of the plate and is oriented so that the generated light radiation propagates in the plate.