In this paper, we present a hybrid refractive-diffractive lens that, when paired with a deep neural network-based image reconstruction, produces high-quality, real-world images with minimal artifacts, reaching a PSNR of 28 dB on the test set. Our diffractive element compensates for the off-axis aberrations of a single refractive element and has reduced chromatic aberrations across the visible light spectrum. We also describe our training set augmentation and novel quality criteria called "false edge level" (FEL), which validates that the neural network produces visually appealing images without artifacts under a wide range of ISO and exposure settings. Our quality criteria (FEL) enabled us to include real scene images without a corresponding ground truth in the training process.
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http://dx.doi.org/10.3390/s23010415 | DOI Listing |
We utilize inverse design and grayscale optical lithography to create a flat lens with a diameter and focal length of 50 mm, operating in the mid-wavelength infrared (MWIR) band. This lens demonstrates an extended depth of focus (DOF ≥±100m), a field of view (FOV ≥20°), and an angular resolution of 300rad. We characterize the lens's performance and use it as the primary optic in a hybrid refractive-diffractive telescope, which increases the angular resolution to 160rad.
View Article and Find Full Text PDFHerein, we report a novel biological hydrogel-based achromatic refractive-diffractive micro-optical element with single-material apochromatism. Benefiting from the stimulated responsive property of the hydrogel, pH modulation yielded swelling and affected the refractive index of the element, enabling multi-wavelength focusing performance tuning and chromatic aberration adjustment. Using femtosecond laser lithography, we fabricated a separate hydrogel microlens and Fresnel zone plate and measured the tunable focusing performance while varying pH; the results were consistent with our simulation results.
View Article and Find Full Text PDFEndoscopic optical diagnostics for IC engines offer the advantage of retaining the full operating range and thermal properties of the production engine. The custom-designed modular hybrid UV endoscope system is optimized for application in IC engines.; however, its hybrid refractive/diffractive relay element is expensive and has a narrow operating wavelength range.
View Article and Find Full Text PDFWe proposed a digital-optical co-design that can effectively improve the image quality of refractive-diffractive hybrid imaging systems over a wide ambient temperature range. Diffraction theory was used to establish the degradation model and blind deconvolution image recovery algorithm was used to perform recovery for simulated images. The peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) were used to evaluate the algorithm performance.
View Article and Find Full Text PDFSensors (Basel)
December 2022
Image Processing Systems Institute of the RAS-Branch of the FSRC "Crystallography and Photonics" RAS, Molodogvardeiskaya St. 151, Samara 443001, Russia.
In this paper, we present a hybrid refractive-diffractive lens that, when paired with a deep neural network-based image reconstruction, produces high-quality, real-world images with minimal artifacts, reaching a PSNR of 28 dB on the test set. Our diffractive element compensates for the off-axis aberrations of a single refractive element and has reduced chromatic aberrations across the visible light spectrum. We also describe our training set augmentation and novel quality criteria called "false edge level" (FEL), which validates that the neural network produces visually appealing images without artifacts under a wide range of ISO and exposure settings.
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