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We present a compact holographic near-eye display system with high-quality speckle-free optical reconstructions using camera-in-the-loop (CITL) optimization with phase constraint strategy. The CITL optimization with phase constraint is used to iteratively synthesize the computer-generated holograms (CGHs) based on the in-system optical feedback. The phase constraint embedded into the whole CGH optimization process can effectively smooth the phase profile of reconstructed wave field, which helps to suppress the speckle noise caused by the phase singularities in CGH reconstruction. Numerical and optical experiments have been performed to demonstrate that the proposed method can provide speckle-free optical reconstructions with excellent image fidelity for holographic near-eye display in a compact setup.

In-line monitoring and routine inspection are essential for using and maintaining complex equipment. The simultaneous implementation of visual positioning and displacement measurement allows the accurate acquisition of characteristics, including object dimensions and mechanical vibrations, while rapidly locking the target position. However, the internal structure of equipment is frequently obscured, making direct visual inspection challenging; therefore, flexible and bendable fiber optic–based endoscopes are extremely valuable in harsh conditions. This study enables all-fiber visual displacement measurement using a single-mode fiber and an imaging fiber bundle. Based on optical triangulation and spot centers extraction method from fiber bundle images, 0.07 mm precision at a measurement distance of 40.12 mm is achieved vertically for rough objects. We demonstrate its surface reconstruction and vibration measurement functions. Factors that affect measurement accuracy, such as light source and object roughness, are also discussed.