The invention relates to a method for calibrating a light source (104) of amedical device (102),wherein the light source (104) is connectable to at least one light-guidingfiber (112) such thatelectromagnetic radiation of a defined light power that is generated by thelight source (104) isat least partly coupled into the light-guiding fiber (112). The medical device(102) is connectedto at least one calibration port (108), wherein the calibration port (108)comprises sensor meansfor determining a spatial emission characteristic of a light-guiding fiber(112) introduced into thecalibration port (108). In this case, the method comprises connecting thelight-guiding fiber (112)to the light source (104), inserting a positioning device (110) for the light-guiding fiber (112) intothe calibration port (108), wherein the positioning device (110) comprises areceiving channelfor receiving the light-guiding fiber (112) and also at least one emissionopening, wherein the atleast one emission opening enables the transmission of a light power coupledout of the light-guiding fiber (112) in at least one defined spatial direction, introducing thelight-guiding fiber(112) into the receiving channel of the positioning device (110), couplingelectromagneticradiation of a defined light power into the light-guiding fiber (112),determining the spatialemission characteristic of the light power coupled out of the light-guidingfiber (112) in theregion of the calibration port (108) as an actual emission characteristic,determining a desiredemission characteristic of the light power coupled out of the light-guidingfiber (112) in theregion of the calibration port (108) for the light power coupled into thelight-guiding fiber (112) bymeans of the sensor means, and comparing the determined actual emissioncharacteristic withthe determined desired emission characteristic. lf the actual emissioncharacteristiccorresponds to the de
