A lighting device provides a lighting unit for emitting useful light and a sensor. The unit includes a laser diode for emitting pump radiation and a phosphor element, which during operation is irradiated by the laser diode and thereby excited and serves for converting the pump radiation into conversion light, which conversion light at least proportionally forms the useful light. The sensor monitors the pump radiation conversion and at the same time detects a conversion light intensity, and is arranged with respect to the phosphor element of the unit so that a portion of the useful light and a measurement portion of the conversion light is incident on the sensor. The lighting device operates so that the phosphor element at least at times is irradiated in a pulsed manner and thereby excited so that between two pulses the conversion light intensity detected by the sensor decreases by at least 10%.