A device for detecting objects in a monitoring range is described, comprising a sensor and an emitter, wherein the emitter includes the following components: a housing, a radiation source for emission of electromagnetic rays and a radiation-conducting device, which is designed to conduct the rays on their path from the radiation source to the point of exit from the emitter, wherein the radiation-conducting device has a focusing element for focusing the rays. The radiation-conducting device is designed to deflect the rays on their path from the radiation source to the point of exit from the emitter by two reflections.