Radiation collector, adapted to collect a portion of a radiation produced by a source and to concentrate said collected portion of the radiation in a spot formed by a convergent output beam produced by said collector, said collector comprising a primary mirror and a secondary mirror, each being rotationally symmetrical about an optical axis (X-X) of the collector, and arranged to reflect the collected portion of the radiation firstly by said primary mirror and then by said secondary mirror, the primary mirror being concave and having a first generatrix in a meridian plane of the device containing the optical axis of the collector, located in the domain [0.8 x R(α); 1.2 x R(α)], R and α being polar coordinates within the meridian plane, R being a radial coordinate measured from a point of the optical axis (X-X) at which the source of radiation is intended to be placed and α being an angular coordinate measured from said optical axis, and R(α) being calculated according to the following equation: R α = R 0 ⋅ exp − α ⋅ tan i where α is expressed in radians, R 0 is a constant length, and i is a constant angle not equal to +/-90°, and the secondary mirror having a second generatrix in said meridian plane, adapted so that said secondary mirror produces the convergent output beam on a side of the collector opposite to the source of radiation, from the collected portion of the radiation reflected by the primary mirror, the second generatrix of the secondary mirror being constituted by points (P 2) having Cartesian coordinates X and Y within the meridian plane, the origin of said Cartesian coordinates being the point of placement of the radiation source and X corresponding to the optical axis of the collector, each point of the second generatrix being located in the domain [0.8 x X(α); 1.2 x X(α)] x [0.8 x Y(α); 1.2 x Y(α)], X(α) and Y(α) being calculated according to the following equations and: X α = 2 ⋅ R α ⋅ cos α ⋅ L − R α ⋅ 1 + cos 2 i + f 2 − L 2 + 2 ⋅ L ⋅ R α ⋅ cos α 2 L − R α ⋅ 1 + cos 2 i + f ⋅ cos α Y α = R α ⋅ sin α + X α − R α ⋅ cos α ⋅ tan α + 2 ⋅ i where α is the angular polar coordinate of equation used for parametrization of the Cartesian coordinates of the second generatrix, R(α) is calculated according to equation, f is the distance between the point of placement of the radiation source and the concentration spot of the collected portion of the radiation, measured along the optical axis (X-X), and L is the length of an optical path between the point of placement of the radiation source and the concentration spot of the collected portion of the radiation, measured along a ray originating from said point of placement of the radiation source and reflected by the primary mirror and then by the secondary mirror. where α is the angular polar coordinate of equation used for parametrization of the Cartesian coordinates of the second generatrix, R(α) is calculated according to equation, f is the distance between the point of placement of the radiation source and the concentration spot of the collected portion of the radiation, measured along the optical axis (X-X), and L is the length of an optical path between the point of placement of the radiation source and the concentration spot of the collected portion of the radiation, measured along a ray originating from said point of placement of the radiation source and reflected by the primary mirror and then by the secondary mirror.