Coregistration errors in multi- and hyperspectral imaging sensors arise when the spatial sensitivity pattern differs between bands or when the spectral response varies across the field of view, potentially leading to large errors in the recorded image data. In imaging spectrometers, spectral and spatial offset errors are customarily specified as "smile" and "keystone" distortions. However these characteristics do not account for errors resulting from variations in point spread function shape or spectral bandwidth. This paper proposes improved metrics for coregistration error both in the spatial and spectral dimensions. The metrics are essentially the integrated difference between point spread functions. It is shown that these metrics correspond to an upper bound on the error in image data. The metrics enable estimation of actual data errors for a given image, and can be used as part of the merit function in optical design optimization, as well as for benchmarking of spectral image sensors.
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http://dx.doi.org/10.1364/OE.20.000918 | DOI Listing |
Biomed Opt Express
January 2025
Key Laboratory of Optical Technology and Instrument for Medicine, Ministry of Education, University of Shanghai for Science and Technology, 200093 Shanghai, China.
Lung cancer with heterogeneity has a high mortality rate due to its late-stage detection and chemotherapy resistance. Liquid biopsy that discriminates tumor-related biomarkers in body fluids has emerged as an attractive technique for early-stage and accurate diagnosis. Exosomes, carrying membrane and cytosolic information from original tumor cells, impart themselves endogeneity and heterogeneity, which offer extensive and unique advantages in the field of liquid biopsy for cancer differential diagnosis.
View Article and Find Full Text PDFComplete 2π cycling of a phase around a phase singularity leads to a rapid phase variation in the nearby zones and forms a sharp local -vector peak. In this paper, the intensity distribution in the spatial domain is transformed into a -vector distribution in the wave vector domain, and we prove that the local -vector peak is generated at the point of minimum light field intensity. The local -vector peak is sharper when the minimum point is closer to the phase singularity.
View Article and Find Full Text PDFA recent advancement in distributed sensing known as the time-expanded phase-sensitive optical time-domain reflectometry (TE Φ-OTDR) addresses the trade-off between spatial resolution and detection bandwidth, enabling centimeter-scale resolution alongside RF detection bandwidth in the order of MHz. To date, TE Φ-OTDR approaches extract the fiber response from the first Nyquist zone (NZ). In this Letter, we propose a post-processing strategy to enhance the SNR by spectrally averaging different NZs.
View Article and Find Full Text PDFWe develop fs laser-fabricated asymmetric couplers and zig-zag arrays consisting of single- and two-mode waveguides with bipartite Kerr nonlinearity in borosilicate (BK7) glass substrates. The fundamental mode ( orbital) is near resonance with the neighboring higher-order orbital, causing efficient light transfer at low power. Due to Kerr nonlinearity, the coupler works as an all-optical switch between and orbitals.
View Article and Find Full Text PDFSci Data
January 2025
Centre for Automation and Robotics (CAR), Spanish National Research Council (CSIC), 28006, Madrid, Spain.
This study highlights the vital role of high-resolution (HR), open-source land cover maps for food security, land use planning, and environmental protection. The scarcity of freely available HR datasets underscores the importance of multi-spectral HR aerial images. We used unmanned aerial vehicle (UAV) to capture images for a centimeter-level orthomosaics, facilitating advanced remote sensing and spatial analysis.
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