Device including a radiation emitter for applying radiation to a target, and related methods

A device for applying radiation to a target, the device comprising:

• a radiation emitter configured to emit electromagnetic radiation having a peak emission wavelength in the range from 10 nm to 1 mm from a radiation emitting surface of the radiation emitter;
• and
• a first reflector that extends in a length direction and has a concave cross section perpendicular to the length direction, the first reflector defining a cavity area having a perimeter, the first reflector having an inward facing reflective border for at least 50% of the perimeter of the cavity area,
• wherein the radiation emitting surface is oriented so as to provide radiation to the cavity area with an intensity distribution I and a maximum intensity Imax,
• wherein the cavity area includes a focal area defined by all points at which a normalized intensity I/Imax is greater than 0.2,
• wherein a width of the focal area is 0.0001 to 0.5 times a width of the cavity area, and
• wherein the width of the focal area and the width of the cavity area are determined along a line passing through a point of maximum intensity Imax and which is parallel to a line joining two end points of the radiation emitting surface of the radiation emitter.