Near-field Fourier ptychography: super-resolution phase retrieval via speckle illumination
- Univ. of Connecticut, Storrs, CT (United States); Harbin Inst. of Technology (China)
- Univ. of Connecticut, Storrs, CT (United States)
- Argonne National Lab. (ANL), Lemont, IL (United States)
- Harbin Inst. of Technology (China)
- Tsinghua Univ., Shenzhen (China)
High spatial resolution is the goal of many imaging systems. While designing a high-resolution lens with diffraction-limited performance over a large field of view remains a difficult task, creating a complex speckle pattern with wavelength-limited spatial features is easily accomplished with a simple random diffuser. With this observation and the concept of near-field ptychography, we report a new imaging modality, termed near-field Fourier ptychography, which is to be used for high-resolution imaging challenges in both microscopic and macroscopic imaging settings. 'Near-field' refers to placing the object at a short defocus distance with a large Fresnel number. We predict a speckle pattern with fine spatial features on the object instead of directly resolving the spatial features via a high-resolution lens. We then translate the object (or speckle) to different positions and acquire the corresponding images by using a low-resolution lens. A ptychographic phase retrieval process is used to recover the complex object, the unknown speckle pattern, and the coherent transfer function at the same time. In a microscopic imaging setup, we use a 0.12 numerical aperture (NA) lens to achieve an NA of 0.85 in the reconstruction process. In a macroscale photographic imaging setup, we achieve similar to 7-fold resolution gain by using a photographic lens. The collection optics do not determine the final achievable resolution; rather, the speckle pattern's feature size does. This is similar to our recent demonstration in fluorescence imaging settings (Guo et al., Biomed. Opt. Express, 9(1), 2018). The reported imaging modality can be utilized in light, coherent X-ray, and transmission electron imaging systems to increase resolution and provide quantitative absorption and object phase contrast.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); National Institutes of Health (NIH); USDOE
- Grant/Contract Number:
- AC02-06CH11357; 1510077; R21EB022378; R03EB022144
- OSTI ID:
- 1524203
- Journal Information:
- Optics Express, Vol. 27, Issue 5; ISSN 1094-4087
- Publisher:
- Optical Society of America (OSA)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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