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 , 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 , 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 . <EOS>