A biological analysis system can include an excitation module and an emission module. The excitation module can include a collimator element for receiving excitation light from the excitation light source and transmitting collimated excitation light in a first direction, and a plurality of excitation mirrors arrayed along the excitation light path, each excitation mirror disposed at an acute angle relative to the first direction and configured to reflect collimated excitation light along a second direction. The emission module can be positioned to receive excitation light transmitted along the second direction and can include a sample block comprising a plurality of sample receptacles positioned to receive a beam of collimated excitation light, and a plurality of photodetectors configured to receive emission light transmitted from a respective sample receptacle in a direction transverse to the second direction of the excitation light path.