Systems and methods for detecting multiple optical signals

A system for detecting two or more different optical emission signals emitted from each of a plurality of reaction receptacles, wherein the reaction receptacles are disposed in a fixed arrangement with respect to each other, said system comprising:

• (A) a plurality of optical sensors, each of said optical sensors being configured to detect one of the two or more optical emission signals and being associated with one of the reaction receptacles so that each reaction receptacle has associated therewith one optical sensor for each optical emission signal to be detected, whereby said optical sensors associated with each of the plurality of reaction receptacles are arranged in a configuration that enables each optical sensor to detect the associated optical emission signal emitted from the associated reaction receptacle;
• (B) a transport mechanism constructed and arranged to effect relative movement between the plurality of reaction receptacles and the optical sensors to sequentially place each reaction receptacle into a signal-detecting position with respect to one of its associated optical sensors, wherein
• (1) each optical sensor is configured to direct an optical excitation signal at an associated reaction receptacle that is in a signal-detecting position with respect to the optical sensor and to detect an optical emission signal emitted from the reaction receptacle that is associated with the excitation signal, and
• (2) each optical sensor is further configured to modulate an excitation signal at an excitation frequency and direct the modulated excitation signal at an associated receptacle, and wherein optical sensors configured to detect at least two different optical emission signals are configured to direct excitation signals of two different excitation frequencies;
• and
• (C) circuitry configured to discard any portion of an optical signal detected by an optical sensor having a frequency that is inconsistent with the excitation frequency of the associated excitation signal.