A particle processing system configured to reduce measurement error due to optical crosstalk between signals from a plurality of adjacent particle interrogation sites, the particle processing system comprising: a particle processing region having a plurality of adjacent particle interrogation sites , the plurality of adjacent particle interrogation sites forming an array; a radiation beam control system to illuminate the plurality of adjacent particle interrogation sites ; and a signal processing system in communication with the particle processing region , the signal processing system including: a signal relay system configured to transmit optical signals emitted from the plurality of adjacent particle interrogation sites , and a multi-element photodetector including a plurality of sensor elements (S) forming an array, wherein the plurality of adjacent particle interrogation sites are mapped via a plurality of optical paths to the plurality of sensor elements (S) within the multi-element photodetector, and wherein the array of sensor elements (S) is associated with the array of interrogation sites such that the mapping of the array of sensor elements (S) is scrambled with respect to the array of interrogation sites so that at least some of the signals from adjacent particle interrogation sites are directed to sensor element locations that are not adjacent. a particle processing region having a plurality of adjacent particle interrogation sites , the plurality of adjacent particle interrogation sites forming an array; a radiation beam control system to illuminate the plurality of adjacent particle interrogation sites ; and a signal processing system in communication with the particle processing region , the signal processing system including: a signal relay system configured to transmit optical signals emitted from the plurality of adjacent particle interrogation sites , and a multi-element photodetector including a plurality of sensor elements (S) forming an array, wherein the plurality of adjacent particle interrogation sites are mapped via a plurality of optical paths to the plurality of sensor elements (S) within the multi-element photodetector, and wherein the array of sensor elements (S) is associated with the array of interrogation sites such that the mapping of the array of sensor elements (S) is scrambled with respect to the array of interrogation sites so that at least some of the signals from adjacent particle interrogation sites are directed to sensor element locations that are not adjacent. a signal relay system configured to transmit optical signals emitted from the plurality of adjacent particle interrogation sites , and a multi-element photodetector including a plurality of sensor elements (S) forming an array, wherein the plurality of adjacent particle interrogation sites are mapped via a plurality of optical paths to the plurality of sensor elements (S) within the multi-element photodetector, and wherein the array of sensor elements (S) is associated with the array of interrogation sites such that the mapping of the array of sensor elements (S) is scrambled with respect to the array of interrogation sites so that at least some of the signals from adjacent particle interrogation sites are directed to sensor element locations that are not adjacent. <EOS>