Intelligent manufacturing has attracted enormous interest in recent years. Since optical spectroscopy provides information on a molecular basis, it will play a major role in the future for the sensor technology. The paper demonstrates that the sensitivity and selectivity of different spectroscopic technologies has fundamental limitations due to the quantum mechanical absorption and scatter cross sections of the individual molecules. Selectivity also plays an important role as it significantly contributes to exploit the fundamental level of detection in multicomponent systems. Furthermore, the applicability and robustness of each technology is dominated by the selection of appropriate light illumination sources and detectors with a good signal to noise ratio.