Ptychography for optical metrology with limited translation knowledge

Area of Science:

• * Optical Metrology
• * Computational Imaging
• * Wavefront Sensing

Background:

• * Ptychography is a powerful lensless imaging technique that reconstructs a sample's complex transmission by computationally combining a series of diffraction patterns.
• * Traditional ptychographic algorithms often assume precise knowledge of the illumination function and probe movement, limiting their applicability in scenarios with motion uncertainty.
• * Optical metrology applications require robust phase retrieval methods that can handle dynamic environments and uncharacterized probe motion.

Purpose of the Study:

• * To develop a novel ptychographic algorithm capable of performing phase retrieval with unknown transverse translation diversity.
• * To enable accurate optical metrology in situations where subaperture motion is poorly characterized.
• * To simultaneously estimate translation parameters, subaperture rotations, and target motion from measured data.

Main Methods:

• * Introduction of the unknown-transverse translation diversity phase retrieval algorithm.
• * Utilization of point spread function (PSF) data to estimate the direction and magnitude of subaperture translation between consecutive measurements.
• * Simultaneous estimation of unknown point target motion and subaperture rotations from the acquired PSF data.

Main Results:

• * Successful demonstration of phase retrieval in the presence of uncharacterized transverse translations.
• * Accurate estimation of subaperture translation direction and distance traveled.
• * Robust estimation of unknown point target motion and subaperture rotations, enhancing overall system performance.

Conclusions:

• * The developed algorithm significantly advances the capabilities of ptychographic optical metrology by accommodating unknown motion.
• * This method provides a robust solution for phase retrieval in dynamic and uncertain environments.
• * The ability to estimate multiple motion parameters enhances the applicability and accuracy of optical metrology techniques.