Abstract: A therapeutic laser with a source of pulsed electromagnetic radiation, a control device for controlling the intensity and/or the duration of the therapeutic laser applied to the tissue, and a detection device for detecting optoacoustic signals triggered by irradiating the living tissue with the pulsed electromagnetic radiation. The therapeutic laser is characterized by an evaluation device that acts on the control device and is used for calculating a degree of quality B(t) from the optoacoustic signals detected by the detection device for individual laser pulses applied to a predetermined laser spot and determining a fit function f(t) at a predetermined point in time ?t1, the fit function f(t) approximating the mean curve of B(t) for 0?t??t1. The intensity and/or the irradiation time of the therapeutic laser is defined by the parameters for the predetermined laser spot, the parameters being determined for the fit function f(t).