Surface Imaging Microscope

摘要

The three-dimensional shapes of microscopic objects are becoming increasingly important for battlespace CBRNEsensing. Potential applications of microscopic 3D shape observations include characterization of biological weaponparticles and manufacturing of micromechanical components. Aerosol signatures of stand-off lidar systems, usingelastic backscatter or polarization, are dictated by the aerosol particle shapes and sizes that must be well characterized inthe lab. A low-cost, fast instrument for 3D surface shape microscopy will be a valuable point sensor for biologicalparticle sensing applications. Both the cost and imaging durations of traditional techniques such as confocalmicroscopes, atomic force microscopes, and electron scanning microscopes are too high. We investigated the feasibility of a low-cost, fast interferometric technique for imaging the 3D surface shape ofmicroscopic objects at frame rates limited only by the camera in the system. The system operates at two laserwavelengths producing two fringe images collected simultaneously by a digital camera, and a specialized algorithm wedeveloped reconstructs the surface map of the microscopic object. The current implementation assembled to test theconcept and develop the new 3D reconstruction algorithm has 0.25 micron resolution in the x and y directions, andabout 0.1 micron accuracy in the z direction, as tested on a microscopic glass test object manufactured with etchingtechniques. We describe the interferometric instrument, present the reconstruction algorithm, and discuss furtherdevelopment.