The invention relates to a device (1) for irradiating tissue (G) with light pulses (L), comprising a housing (2), at least one light source (3) for emitting the light pulses (L) with a wavelength (lambda) of from 600 nm to 660 run, a modulator (4) and a power stage (6) for generating the light pulses (L), and with an activating element (5). For creating a device (1) which is as small, as cost-efficient and as effective as possible, by which as good a therapy success as possible is achieved in various applications, the modulator (4) is designed for generating the light pulses (L) with a pulse frequency (f) of from 1 to 10 Hz, and the power stage (6) is designed for emitting the light pulses (L) with an energy which causes breaking up of the photosensitizer in the photodynamic therapy and evokes a frequency doubling or a two-photon absorption (TPA) in the tissue (G) when treating inflammations without a sensitizer.
