A portable spectroscopic device for acquiring single-frame spatial, spectral, and polarization information of an object. The device includes a modular dispersion element assembly that is coupled to a mobile computing device and disperses light into a plurality of different wavelengths. The mobile computing device includes a sensor and is configured to receive and analyze the plurality of wavelengths. The mobile computing device is also configured to perform automatic calibrations to determine the absolute wavelength axis and make stray-light corrections with minimal user intervention, thus making it amenable for untrained users not familiar with the state of the art. The mobile computing device is also configured to extend dynamic range.