1. A method comprising: providing a first amount of illumination light to one or more structures disposed on a semiconductor wafer, the one or more structures having an unknown spectral response, the first amount of illumination light provided by an illuminator of a reference metrology system; detecting a first plurality of intensities of light from the one or more structures in response to the first amount of illumination light provided to the semiconductor wafer, the detected first plurality of intensities comprising a first amount of raw measurement data, the first plurality of intensities of light detected by a spectrometer of the reference metrology system; determining a first spectral response measurement of the one or more structures based at least in part on the first amount of raw measurement data and one or more system parameter values associated with the reference metrology system that provides the first amount of illumination light and detects the first amount of raw measurement data; providing a second amount of illumination light to the one or more structures disposed on the semiconductor wafer, the second amount of illumination light provided by an illuminator of a target metrology system; detecting a second plurality of intensities of light from the one or more structures in response to the second amount of illumination light provided to the semiconductor wafer, the detected second plurality of intensities comprising a second amount of raw measurement data, the second plurality of intensities of light detected by a spectrometer of the target metrology system; determining values of one or more system parameters associated with the target metrology system that provides the second amount of illumination light and detects the second amount of raw measurement data such that an error function that includes a difference between the first spectral response measurement and a second spectral response measurement of the one or more structures measured by the target metrology system is minimized, wherein the second spectral response measurement is determined based at least in part on the second amount of raw measurement data detected by the target metrology system and the values of the one or more system parameters associated with the target metrology system, wherein at least one value of at least one of the one or more system parameter values associated with the target metrology system is different from at least one value of at least one of the one or more system parameter values associated with the reference metrology system; and storing the values of the one or more system parameters of the target metrology system in a memory.