Zoom System For Coherent Imaging With No Moving Lens Groups

Traditional optical zoom systems in precision metrology instruments face challenges such as image drift, focus shifts, and complex optical arrangements. Conventional zoom methods, including continuously variable zoom lenses and turreted fixed-focal-length lenses, introduce alignment difficulties, optical artifacts, and mechanical complexity.

This article presents a novel zoom system designed specifically for Phase Shifting Interferometry (PSI) instruments, addressing these shortcomings. The proposed system features a high-resolution detector, a fixed-focus imaging lens, and a variable aperture stop. Instead of adjusting focal lengths with moving lenses, the system bins detector pixels according to magnification levels while dynamically modifying the aperture stop to maintain diffraction-limited resolution. This approach eliminates image drift and focal shifts, ensuring consistent calibration across zoom levels.

The new design offers multiple advantages over traditional zoom systems. It ensures stable image positioning, maintains accurate lateral calibration, and improves light sensitivity by leveraging pixel binning at lower magnifications. Additionally, by eliminating complex moving optical elements, the system reduces manufacturing costs while achieving high precision and reliability.

By simplifying zoom mechanics while preserving high optical performance, this method enhances metrology capabilities, making interferometry instruments more accessible and effective for precision measurement applications. This innovation represents a significant advancement in zoom technology for high-resolution optical metrology, ensuring improved performance, cost-efficiency, and user experience.