Development of a Spatial Resolution-Enhanced Digital-Hologram Microscope With a Liquid Crystal Phase Modulator

We proposed a DHM system with improved spatial resolution compared with that of the polarized camera-based DHM system by employing a liquid crystal phase modulator (LCPM). The LCPM-based holographic interferometry optical system can reliably construct a four-step phase shifting scheme by changing the applied voltage, thus eliminating the need for mechanical moving parts. The spatial resolution characteristics of the proposed DHM system were analyzed using the 1951 USAF resolution target. These characteristics showed a fourfold improvement over the polarized camera-based DHM system. Additionally, the 3D information capturing capability of the proposed DHM system was experimentally confirmed using a via-hole array sample produced through the semiconductor fabrication process.