A system (110; 260) configured to measure absorbance and fluorescence of a sample, comprising: an input light source (202; 262) configured to generate at least one excitation wavelength; a chamber (214; 282) positioned to receive the sample and to be illuminated by the at least one excitation wavelength from the input light source (202; 262); a spectrograph comprising a single multi-channel detector (250; 294) configured to receive and detect both light transmitted through the sample during an absorbance measurement, and light emitted by the sample along a path generally perpendicular to an excitation optical path during a fluorescence measurement in response to illumination by the at least one excitation wavelength; an emission filter, or the combination of a focusing mirror and a beam combiner, the focusing mirror arranged to direct light emitted by the sample during the fluorescence measurement to the beam combiner, the beam combiner being configured to transmit the fluorescence light toward the spectrograph and to reflect light passing through the sample during the absorbance measurement toward the spectrograph, the emission filter or the combination of the focusing mirror and the beam combiner being arranged to direct the light emitted by the sample along the path generally perpendicular to the excitation optical path during the fluorescence measurement to the spectrograph, wherein the fluorescence light emitted by the sample during the fluorescence measurement is directed to the spectrograph without passing through any optical fiber; and an optical fiber (220; 292) configured to receive the light transmitted through the sample and, for the case of the system comprising the emission filter, the optical fiber being arranged to direct the transmitted light to the spectrograph directly, or, for the case of the system comprising the combination of the focusing mirror and the beam combiner, the optical fiber being arranged to direct the transmitted light to the spectrograph via the beam combiner during the absorbance measurement. an input light source (202; 262) configured to generate at least one excitation wavelength; a chamber (214; 282) positioned to receive the sample and to be illuminated by the at least one excitation wavelength from the input light source (202; 262); a spectrograph comprising a single multi-channel detector (250; 294) configured to receive and detect both light transmitted through the sample during an absorbance measurement, and light emitted by the sample along a path generally perpendicular to an excitation optical path during a fluorescence measurement in response to illumination by the at least one excitation wavelength; an emission filter, or the combination of a focusing mirror and a beam combiner, the focusing mirror arranged to direct light emitted by the sample during the fluorescence measurement to the beam combiner, the beam combiner being configured to transmit the fluorescence light toward the spectrograph and to reflect light passing through the sample during the absorbance measurement toward the spectrograph, the emission filter or the combination of the focusing mirror and the beam combiner being arranged to direct the light emitted by the sample along the path generally perpendicular to the excitation optical path during the fluorescence measurement to the spectrograph, wherein the fluorescence light emitted by the sample during the fluorescence measurement is directed to the spectrograph without passing through any optical fiber; and an optical fiber (220; 292) configured to receive the light transmitted through the sample and, for the case of the system comprising the emission filter, the optical fiber being arranged to direct the transmitted light to the spectrograph directly, or, for the case of the system comprising the combination of the focusing mirror and the beam combiner, the optical fiber being arranged to direct the transmitted light to the spectrograph via the beam combiner during the absorbance measurement.