Optical element for light concentration for a predetermined wavelength range, having: a holding sleeve, which is shaped in such a way that a light passage volume is framed by at least one reflective partial surface of the holding sleeve; and a light transmission body, with which the light passage volume is completely filled and which is transmissive at least for the predetermined wavelength range, wherein the light transmission body has a light collection surface with a first area content on a first side and a light exit surface with a second area content, which is less than the first area content, on a second side; wherein the light transmission body is formed at least partially from at least one medium which is diffuse for the predetermined wavelength range and has at least a first subregion with at least a first diffusivity (D1, D3 to D6) and a second subregion with at least a second diffusivity, which is different from the first diffusivity (D1, D3 to D6), and wherein at least one central longitudinal axis extending from the light collection surface to the light exit surface and intersecting the light transmission body can be defined, and wherein the diffusivity distribution of the light transmission body is rotationally symmetrical with respect to the central longitudinal axis, characterized in that the first subregion with the first diffusivity (D1, D3 to D6) lies on the light exit surface and has a varying layer thickness, which is minimal on the central longitudinal axis and maximal on the at least one reflective partial surface, and wherein the second subregion with at least the second diffusivity lies on the light collection surface and has a varying layer thickness, which is maximal on the central longitudinal axis and minimal on the at least one reflective partial surface. a holding sleeve, which is shaped in such a way that a light passage volume is framed by at least one reflective partial surface of the holding sleeve; and a light transmission body, with which the light passage volume is completely filled and which is transmissive at least for the predetermined wavelength range, wherein the light transmission body has a light collection surface with a first area content on a first side and a light exit surface with a second area content, which is less than the first area content, on a second side; wherein the light transmission body is formed at least partially from at least one medium which is diffuse for the predetermined wavelength range and has at least a first subregion with at least a first diffusivity (D1, D3 to D6) and a second subregion with at least a second diffusivity, which is different from the first diffusivity (D1, D3 to D6), and wherein at least one central longitudinal axis extending from the light collection surface to the light exit surface and intersecting the light transmission body can be defined, and wherein the diffusivity distribution of the light transmission body is rotationally symmetrical with respect to the central longitudinal axis, characterized in that the first subregion with the first diffusivity (D1, D3 to D6) lies on the light exit surface and has a varying layer thickness, which is minimal on the central longitudinal axis and maximal on the at least one reflective partial surface, and wherein the second subregion with at least the second diffusivity lies on the light collection surface and has a varying layer thickness, which is maximal on the central longitudinal axis and minimal on the at least one reflective partial surface.