A signal detection system configured for detecting a signal emitted by the contents of a reaction receptacle is also configured to apply thermal energy to a portion of the reaction receptacle to affect a reaction occurring within the reaction receptacle. More particularly, a system for detecting electromagnetic radiation emitted by the contents of a reaction receptacle includes a transmission element configured for transmitting electromagnetic radiation from the contents of the receptacle, a thermal element associated with the transmission element and configured to apply thermal energy to at least a portion of the receptacle, and a detector configured to receive electromagnetic radiation from the transmission element and to generate a signal corresponding to a characteristic of the electromagnetic radiation received by the detector.