image: Figure | Schematic of disturbance-introduced interferometry (DII). a Interferometer main body. b Phase information is encoded into the interference patterns via random mechanical disturbances (RMDs), including vibration, support flexible deformation, and random micro-displacement. c Sequential acquisition of interference images under various disturbance conditions. d Extraction of the embedded phase information from the recorded interference patterns through the natural phase decoding algorithm (NPDA).
Credit: Jiamiao Yang et al.
Phase-shifting interferometry (PSI) is a gold-standard technique for high-precision surface metrology, but it relies heavily on strict vibration isolation and precise phase control. In real-world scenarios, especially for large-aperture optics, environmental disturbances often make such conditions difficult to achieve.
To address this challenge, a team led by Professor Jiamiao Yang proposed disturbance-introduced interferometry (DII), which turns unavoidable mechanical disturbances into useful phase-shifting signals. Instead of suppressing vibration, DII uses random mechanical disturbances such as structural vibration, support deformation, and micro-displacement to dynamically modulate the optical path difference, naturally encoding surface phase information into a sequence of interferograms.
To decode these disturbance-modulated signals, the team developed a natural phase decoding algorithm (NPDA). The algorithm first performs a coarse estimation of disturbance phase for each frame, then filters out undersampled or distorted interferograms, and finally refines the surface phase through iterative decoupling of spatial and temporal variables. This adaptive strategy enables accurate phase retrieval even under large-amplitude disturbances, eliminating the need for dedicated phase-shifting devices.
Numerical simulations demonstrate that DII maintains strong robustness across a wide disturbance range. Even when the disturbance phase amplitude reaches 7 pi radians, the reconstruction error remains as low as 0.0005 wavelength, while conventional four-step PSI fails with errors up to 0.5 wavelength. Compared with advanced disturbance-resistant algorithms tested, its tolerable disturbance amplitude is improved by more than 20 times.
Experimental results further confirm its performance. Under significant vibration conditions using only a standard office desk for support, DII achieves wavefront repeatability better than 0.0018 wavelength. Its results closely match those obtained by conventional PSI under strictly controlled conditions, with RMS differences as low as 0.0002 wavelength for spherical surfaces and 0.0007 wavelength for flat surfaces. In contrast, traditional PSI cannot provide reliable measurements under the same dynamic disturbances.
By fundamentally redefining vibration as a useful signal rather than noise, DII offers a robust and practical solution for high-precision interferometric measurement in complex environments, with strong potential for applications such as large-aperture optics testing and in-situ industrial metrology.
Journal
Light: Advanced Manufacturing
Article Title
Disturbance-Introduced Interferometry: Surface Topography Metrology Beyond Vibration Isolation and Phase-Shifting Control