Mixture Detection Using a Deep-UV Raman-LIBS Autofocus-Based Compact Chemical Spectroscopic Sensor

We present a compact, multifunctional chemical sensor that seamlessly integrates deep-UV Raman and laser-induced breakdown spectroscopy (LIBS) modalities into a single lightweight hand-held unit. By employing a single 266 nm laser source (1.5 ns pulse width, 10 mW average power) and an integrated autofocus mechanism, this design overcomes the complexities associated with systems that rely on dual or multiple laser wavelengths (e.g., 532 or 1064 nm). The 3D-printed sensor body weighs only 38 g and occupies a compact volume of 70 × 60 × 40 mm³ (that can fit within a palm of a hand) enabling comfortable hand-held operation in both laboratory and field environments. When combined with a 215 g deep-UV compact laser unit and a 90 g compact but high-resolution spectrometer (which is possible only with deep-UV operation), the overall system weight remains under 500 g, reinforcing its suitability for highly mobile applications. The functionality of the sensor is demonstrated for mixture detection in (a) a complex mineral-planetary simulant mixture, (b) isotope mixture, and (c) an organic-inorganic mixture. The deep-UV 266 nm operation allowed mixture detection to as low as 0.1% with such a compact sensor, which is only possible with bulky intensified CCDs previously reported with visible/IR wavelengths. The deep-UV excitation enhances Raman signal strength and reduces fluorescence interference, while the integrated autofocus capability facilitates seamless switching between LIBS and Raman operation modes. Compared to existing integrated approaches, this single-laser design significantly reduces optical complexity and overall system footprint, offering a robust solution for in situ chemical analyses ranging from environmental monitoring to planetary exploration.