Edge information of images contains a variety of physical properties such as amplitude, phase, polarization, and frequency. These features usually correspond to the changes of the key structure of objects under measured. Therefore, edge imaging is of great significance in computer vision and optical detection. Here, we propose a controllable edge-enhanced imaging system with weak measurement, utilizing a Pancharatnam-Berry phase metasurface to achieve weak coupling between light and object. By setting the proper pre-selection state and post-selection state, high-contrast edge images are successfully obtained in demonstration experiments. Due to the utilization of metasurface, the proposed system significantly simplifies the complexity of traditional optical imaging methods while maintaining weak coupling controllability. Furthermore, by fine-tuning polarization states in measuring, the real and imaginary parts of the weak value can be flexibly adjusted. Therefore, a continuously adjustable observation between the edge-enhanced imaging mode and the complete imaging mode is achieved. This method provides a promising optical solution for multi-scale image detection.
Edge information of images contains a variety of physical properties such as amplitude, phase, polarization, and frequency. These features usually correspond to the changes of the key structure of objects under measured. Therefore, edge imaging is of great significance in computer vision and optical detection. Here, we propose a controllable edge-enhanced imaging system with weak measurement, utilizing a Pancharatnam-Berry phase metasurface to achieve weak coupling between light and object. By setting the proper pre-selection state and post-selection state, high-contrast edge images are successfully obtained in demonstration experiments. Due to the utilization of metasurface, the proposed system significantly simplifies the complexity of traditional optical imaging methods while maintaining weak coupling controllability. Furthermore, by fine-tuning polarization states in measuring, the real and imaginary parts of the weak value can be flexibly adjusted. Therefore, a continuously adjustable observation between the edge-enhanced imaging mode and the complete imaging mode is achieved. This method provides a promising optical solution for multi-scale image detection.
Phase distribution is crucial for obtaining the whole information of phase object in imaging. However, due to the transparency of phase objects, the phase distribution cannot be obtained in traditional bright-field imaging. Here, we propose a phase distribution reconstruction based on the imaginary value of weak measurement, which is achieved by a Pancharatnam–Berry phase metasurface. Moreover, by adjusting the weak value to a real weak value, amplitude reconstruction can also be achieved. Different parts of weak values can be obtained by controlling the preselection and postselection states. The weak interaction is achieved by the metasurface, which is convenient to control the weak coupling and reduce the complexity of the experimental setup at the same time. Furthermore, the edge contour of objects can also be acquired by the weak measurement, and the edge sharpness is related to types of the weak values, which plays an important role in image resolution. Our method paves a way for quantitative phase imaging and unlabeled biological imaging.
Traditional quantum imaging is featured by remarkable sensitivity and signal-to-noise ratio, but limited by bulkiness and static function (either phase contrast imaging or edge detection). Our report synergizes a polarization-entangled source with a metasurface consisting of various sophisticatedly engineered spatial frequency segments. By tuning polarization, we demonstrate multiple "on"-state quantum imaging modes, enabling flexible switching between phase contrast, edge, and arbitrary superimposed imaging mode. Furthermore, the "off"-state, which characterizes the background noise, enables self-calibration of the system by subtracting this noise in "on"-state modes, resulting in self-enhanced edge detection. Our approach performs phase contrast imaging with a phase difference of π/4 present in the target object, and edge imaging capable of detecting tiny (radius about 2 μm) defects, maintaining high image contrast (phase contrast of 0.726, and enhanced edge contrast of 0.902). Our results provide insights into constructive duet between quantum imaging and metaoptics.
In standard quantum weak measurements, preselection and postselection of quantum states are implemented in the same photon. Here we go beyond this restrictive setting and demonstrate that the preselection and postselection can be performed in two different photons, if the two photons are polarization entangled. The Pancharatnam-Berry phase metasurface is incorporated in the weak measurement system to perform weak coupling between probe wave function and spin observable. By introducing nonlocal weak measurement into the microscopy imaging system, it allows us to remotely switch different microscopy imaging modes of pure-phase objects, including bright-field, differential, and phase reconstruction. Furthermore, we demonstrate that the nonlocal weak-measurement scheme can prevent almost all environmental noise photons from detection and thus achieves a higher image contrast than the standard scheme at a low photon level. Our results provide the possibility to develop a quantum nonlocal weak-measurement microscope for label-free imaging of transparent biological samples.
Phase contrast microscopy is essential in optical imaging, but traditional systems are bulky and limited by single-phase modulation, hindering visualization of complex specimens.Metasurfaces, with their subwavelength structures, offer compact integration and versatile light field control.Quantum imaging further enhances performance by leveraging nonclassical photon correlations to suppress classical noise, improve contrast, and enable multifunctional processing.Here, we report, a dual-mode bright-dark phase contrast imaging scheme enabled by quantum metasurface synergy.By combining polarization entanglement from quantum light sources with metasurface phase modulation, our method achieves highcontrast, adaptive bright-dark phase contrast imaging of transparent samples with arbitrary phase distributions under low-light conditions.Compared to classical weak light imaging, quantum illumination suppresses environmental noise at equivalent photon flux, improving the contrast from 0.22 to 0.81.Moreover, quantum polarization entanglement enables remote switching to ensure high-contrast imaging in at least one mode, supporting dynamic observation of biological cells with complex phase structures.This capability is especially valuable in scenarios where physical intervention is difficult, such as in miniaturized systems, in vivo platforms, or extreme environments.Overall, the proposed scheme offers an efficient noninvasive solution for biomedical imaging with strong potential in life science applications.
Metasurfaces consisting of engineered dielectric or metallic structures provide unique solutions to realize exotic phenomena including negative refraction, achromatic focusing, electromagnetic cloaking, and so on. The intersection of metasurface and quantum optics may lead to new opportunities but is much less explored. Here, we propose and experimentally demonstrate that a polarization-entangled photon source can be used to switch ON or OFF the optical edge detection mode in an imaging system based on a high-efficiency dielectric metasurface. This experiment enriches both fields of metasurface and quantum optics, representing a promising direction toward quantum edge detection and image processing with remarkable signal-to-noise ratio.
Metasurfaces have shown extraordinary abilities to manipulate the phase and polarization of light and thus hold great promise for applications in photonics and optoelectronics. Here, we propose a unique application of the dielectric metasurface for quantum weak measurements. In our scheme, the dielectric metasurface introduces a tiny phase gradient in the procedure of measurements and keeps the measured system almost undisturbed. The dielectric metasurface may improve and simplify already existing schemes in quantum weak measurements and thereby provide potential applications in precise measurements of phase, polarization, and frequency of light.