An irradiation unit is disclosed that includes a pump radiation source for emitting pump radiation in the form of a beam, a conversion element for at least partially converting the pump radiation into conversion radiation, and a support on which the conversion element is situated. The support accommodates a through-hole through which the beam including the pump radiation is incident on an incident surface of the conversion element, the though-hole being laterally delimited by an inner wall face of the support, at least one portion of the face tapering in the direction of the incident surface. During operation, the pump radiation conducted in the beam is at least intermittently at least in part, incident on the inner wall face of the support and is reflected thereby onto the incident surface.