Large Gradient Micro-Structure Topography Measurement with Multi-Angle Stitching Digital Holographic Microscope

We present an effective method for the topography characterization of large gradient micro-structure based on digital holographic microscope (DHM). Due to the limitation of numerical aperture of DHM system, high frequency information corresponding to large gradient regions of specimen is prohibited from entering the imaging system and the complete collection of specimen features cannot be implemented. To solve this problem, we use a common configuration of off-axis DHM system to capture the holograms from multiple angles of the sample, and the various object waves coming from the sample of different tilt angle is corrected and spliced into a fully topography by multi-angle stitching process. In this way, the measurement of large gradient topography of specimen can be realized. Experimental results of large gradient microlens demonstrate the practicability and precision of the presented method.