Synthetic aperture radar(SAR)utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes.As the aircraft travels across a designated area,it synthesizes a large virtual aperture...Synthetic aperture radar(SAR)utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes.As the aircraft travels across a designated area,it synthesizes a large virtual aperture to improve image resolution.Inspired by SAR,we introduce synthetic aperture ptycho-endoscopy(SAPE)for micro-endoscopic imaging beyond the diffraction limit.SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens.The fiber cores at the distal tip modulate the diffracted wavefield within a confined area,emulating the role of the‘airborne antenna’in SAR.The handheld operation introduces positional shifts to the tip,analogous to the aircraft’s movement.These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle’s physical limit.We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle’s modulation profile.Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target.The achieved space-bandwidth product is~1.1 million effective pixels,representing a 36-fold increase compared to that of the original fiber bundle.Furthermore,SAPE’s refocusing capability enables imaging over an extended depth of field exceeding 2 cm.The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe’s maximum collection angle,opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.展开更多
基金supported by the National Institute of Health R01-EB034744(G.Z.)the UConn SPARK grant(G.Z.),National Science Foundation 2012140(G.Z.)the National Institute of Health U01-NS113873(B.F.and G.Z.).
文摘Synthetic aperture radar(SAR)utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes.As the aircraft travels across a designated area,it synthesizes a large virtual aperture to improve image resolution.Inspired by SAR,we introduce synthetic aperture ptycho-endoscopy(SAPE)for micro-endoscopic imaging beyond the diffraction limit.SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens.The fiber cores at the distal tip modulate the diffracted wavefield within a confined area,emulating the role of the‘airborne antenna’in SAR.The handheld operation introduces positional shifts to the tip,analogous to the aircraft’s movement.These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle’s physical limit.We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle’s modulation profile.Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target.The achieved space-bandwidth product is~1.1 million effective pixels,representing a 36-fold increase compared to that of the original fiber bundle.Furthermore,SAPE’s refocusing capability enables imaging over an extended depth of field exceeding 2 cm.The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe’s maximum collection angle,opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.
