Optical proximity correction (OPC) is essential for advanced semiconductor manufacturing beyond 45nm node by improving lithography resolution. However, traditional OPC techniques are limited by scalar imaging models and gradient-based algorithms. This study introduces a physics-driven deep learning OPC scheme that leverages vector imaging model. Guided by inverse lithography technology (ILT), the algorithm requires no extensive datasets, relying instead on varied, randomly generated patterns for training. The results from numerical testing confirm the approach's accuracy and efficiency.
Planar cameras with high performance and wide field of view (FOV) are critical in various fields, requiring highly compact and integrated technology. Existing wide FOV metalenses show great potential for ultrathin optical components, but there is a set of tricky challenges, such as chromatic aberrations correction, central bright speckle removal, and image quality improvement of wide FOV. We design a neural meta-camera by introducing a knowledge-fused data-driven paradigm equipped with transformer-based network. Such a paradigm enables the network to sequentially assimilate the physical prior and experimental data of the metalens, and thus can effectively mitigate the aforementioned challenges. An ultra-wide FOV meta-camera, integrating an off-axis monochromatic aberration-corrected metalens with a neural CMOS image sensor without any relay lenses, is employed to demonstrate the availability. High-quality reconstructed results of color images and real scene images at different distances validate that the proposed meta-camera can achieve an ultra-wide FOV (>100 deg) and full-color images with the correction of chromatic aberration, distortion, and central bright speckle, and the contrast increase up to 13.5 times. Notably, coupled with its compact size (< 0.13 cm3), portability, and full-color imaging capacity, the neural meta-camera emerges as a compelling alternative for applications, such as micro-navigation, micro-endoscopes, and various on-chip devices.
Two-photon microscopy (TPM) is one of the most important imaging techniques in biological imaging since it was invented in 1990s. Due to its unique capabilities, this technique enables noninvasive study of scattering biological specimens in three dimensions with submicrometer resolution and penetration depth up to a few hundred micrometers. Focal modulation microscopy (FMM) provides sub-cellular spatial resolution at large penetration depths in tissue samples by rejecting out-of-focus signal. Combined with focal modulation techniques, this paper proposes two-photon focal modulation microscopy (TPFMM) to further enhance penetration depth by bringing a spatiotemporal phase modulator (STPM) in the TPM. The STPM is equivalent to a time-dependent phase-only pupil filter that alternates between a homogeneous filter and an inhomogeneous filter. When the STPM is homogeneous, the excitation beam is properly focused into the focal volume by the objective lens. The inhomogeneous filter is so designed that it leads to redistribution of the excitation beam and minimize the focal intensity, which can be binary phase and continuous phase distribution. Using the vectorial diffraction theory, we have theoretically demonstrated that TPFMM with the designed STPM can significantly suppress the background contribution from out-of-focus ballistic excitation and achieve almost the same resolution as TPM. The improved background rejection of this imaging modality, enabled by focal modulation, are quantified with three dimensional imaging data obtained from fluorescent beads and fixed tissue samples using a home-made TPFMM. These investigations have its potential to extend the penetration depth of nonlinear microscopy in imaging multiple-scattering biological tissues, such as mouse brain.
A spatiotemporal phase modulator (STPM) is theoretically investigated using the vectorial diffraction theory. The STPM is equivalent to a time-dependent phase-only pupil filter that alternates between a homogeneous filter and a stripe-shaped filter with a sinusoidal phase distribution. It is found that two-photon focal modulation microscopy (TPFMM) using this STPM can significantly suppress the background contribution from out-of-focus ballistic excitation and achieve almost the same resolution as two-photon microscopy. The modulation depth is also evaluated and a compromise exists between the signal-to-background ratio and signal-to-noise ratio. The theoretical investigations provide important insights into future implementations of TPFMM and its potential to further extend the penetration depth of nonlinear microscopy in imaging multiple-scattering biological tissues.
KEYWORDS: Modulation, Microscopy, Line scan image sensors, Microsoft Foundation Class Library, Luminescence, Image filtering, Optical filters, Tissues, Geometrical optics, Scattering
Line-scan focal modulation microscopy (LSFMM) is an emerging imaging technique that affords high imaging speed and good optical sectioning at the same time. We present a systematic investigation into optimal design of the pupil filter for LSFMM in an attempt to achieve the best performance in terms of spatial resolutions, optical sectioning, and modulation depth. Scalar diffraction theory was used to compute light propagation and distribution in the system and theoretical predictions on system performance, which were then compared with experimental results.
As a non-invasive technique, optical imaging has become a widely used tool in both biological research and clinical diagnostics to investigate biological tissues. A key parameter to consider is the penetration depth of optical imaging in the tissues. Several techniques have been developed to enhance the penetration depth of optical imaging within scattering biological tissues, such as optical coherence microscopy (OCM) and multi-photon microscopy (MPM). Recently, focal modulation microscopy (FMM) has been developed and an imaging depth comparable to these techniques has been achieved. Here, combined with focal modulation techniques, two-photon focal modulation microscopy (TPFMM) is demonstrated theoretically and experimentally. First, TPFMM in turbid media using a novel spatiotemporal phase modulator (STPM) is theoretically investigated using the vector diffraction theory. At the destructive stage during the excitation beam modulation, this STPM is equivalent to a strip-shaped pupil filter with a sinusoidal phase distribution. Compared to the previous filter patterns with sharp phase transitions, the contribution of out-of-focus ballistic excitation to the background is largely reduced using the continuous phase filters. In addition, this new STPM has been designed and integrated into TPFMM to achieve high performance imaging of the biological tissues. It is found that TPFMM using this new STPM can significantly suppress scattered excitation and reduce out-of-focus ballistic excitation with acceptable modulation depth and resolution. Therefore, TPFMM with some new STPMs has the great potential to further extend the penetration depth in imaging the scattering biological tissues.
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