Spectrometers and methods for determining the presence or absence of a material in proximity to and/or combined with another material are provided. In one particular example, a spectrometer is provided that includes a light source, a detector and an optical system. In this implementation, the light source is configured to provide an excitation incident beam. The detector is configured to detect a spectroscopy signal. The optical system is configured to direct the excitation incident beam toward a sample at a non-zero angle from a zero-angle reference. The optical system is further configured to receive a spectroscopy signal from the sample and provide the spectroscopy signal to the detector. The detector is configured to remove a spectral interference component of the spectroscopy signal.