Detection system for detecting at least one substance in a measurement region, wherein the detection system comprises a receiver-side homogenization apparatus and a receiver, wherein the homogenization apparatus is configured to homogenize at least a part of a photon field that emerges from the measurement region in a field direction and comprises a first diffuser, a second diffuser and a converging lens, wherein, viewed in the field direction, the first diffuser is arranged downstream of the measurement region and the second diffuser is arranged downstream of the first diffuser and at a diffuser distance from the first diffuser in a manner such that at least a part of the photon field emerging from the measurement region penetrates both diffusers (10, 12), wherein the first diffuser is configured to homogenize an input photon field incident on the homogenization apparatus and thereby to produce an intermediate photon field, wherein the second diffuser is configured to further homogenize the intermediate photon field and thereby to produce an output photon field that propagates in the field direction towards the receiver, and wherein the receiver, - viewed in the field direction, is arranged downstream of the second diffuser in a manner such - that at least a part of the homogenized photon field that has emerged from the measurement region is incident on the receiver, and - is configured to produce signals depending on the incident photon field, characterized in that the first diffuser is arranged at the converging lens or forms an integral part of the converging lens. wherein the detection system comprises a receiver-side homogenization apparatus and a receiver, wherein the homogenization apparatus is configured to homogenize at least a part of a photon field that emerges from the measurement region in a field direction and comprises a first diffuser, a second diffuser and a converging lens, wherein, viewed in the field direction, the first diffuser is arranged downstream of the measurement region and the second diffuser is arranged downstream of the first diffuser and at a diffuser distance from the first diffuser in a manner such that at least a part of the photon field emerging from the measurement region penetrates both diffusers (10, 12), wherein the first diffuser is configured to homogenize an input photon field incident on the homogenization apparatus and thereby to produce an intermediate photon field, wherein the second diffuser is configured to further homogenize the intermediate photon field and thereby to produce an output photon field that propagates in the field direction towards the receiver, and wherein the receiver, - viewed in the field direction, is arranged downstream of the second diffuser in a manner such - that at least a part of the homogenized photon field that has emerged from the measurement region is incident on the receiver, and - is configured to produce signals depending on the incident photon field, - viewed in the field direction, is arranged downstream of the second diffuser in a manner such - that at least a part of the homogenized photon field that has emerged from the measurement region is incident on the receiver, and - is configured to produce signals depending on the incident photon field, characterized in that the first diffuser is arranged at the converging lens or forms an integral part of the converging lens.