Embedded optics and electronics single digital micromirror device-based agile pixel broadband imager and spectrum analyzer for laser beam hotspot detection

To the best of the authors, knowledge, proposed is the first embedded optics and electronics-based agile pixel broadband optical imager and spectrum analyzer using a single digital micromirror device (DMD) for laser beam hotspot detection. Specifically, the novel design engages both the wavelength-dependent grating structure of the DMD optical chip and its three-tilt-state micromirror programmability to form both an optical spectrum analyzer (OSA) and an agile pixel imager within one basic instrument. Also, to our knowledge, presented for the first time for a DMD chip is a complete mathematical analysis for incident laser beam operations via diffraction theory. Using off-the-shelf components and the Texas Instruments (TI) Lightcrafter DLP chip and drive electronics, embedded engineering of the proposed instrument is implemented for the visible laser wavelength band. Experimental OSA operation of the instrument is demonstrated using classic laser wavelengths of 633 and 532 nm with beam power levels of 20 and 180 mW, respectively. Experimental imaging operation of the instrument compared with a commercial scanning slit-based laser beam profiler is successfully conducted for a 633 nm test laser beam having a hotspot with ≈68%peak-to-null power drop near its center. Applications for the proposed imager-OSA instrument include laser beam testing during laser assembly and manufacturing operations.