The present description relates to a baby carriage comprising two rear wheels and a front wheel, a chassis that is carried by said wheels, a seat carried in the chassis and intended for a passenger, as well as a folding stand. The illumination optical system includes a reflection integrator adapted to form a plurality of secondary light sources with the light from the exposure light source, a condenser unit adapted to superimpose beams of light from the secondary light sources with one another on the reflection mask, and a mirror capable of being disposed in an optical path instead of the reflection integrator. 0 m and a specific surface area below 6 m2g.