Abstract: A therapeutic irradiation device may include: a source configured to emit electromagnetic radiation in a predetermined spectral range, a sensor configured to detect electromagnetic radiation in the predetermined spectral range of the electromagnetic radiation emitted by the source and to output a signal indicative of a power of the detected radiation, and a controller configured to monitor a magnitude of the signal output by the sensor and to compare the magnitude of the signal with a predetermined magnitude range, wherein the controller is configured to identify a time period during which the magnitude of the signal output by the sensor is included in the predetermined range.