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The solar cell is key photovoltaic (PV) device that converts light energy into electricity, and its surface defects are the main reason for the decrease in the efficiency of PV systems. Conventional solar cell defect detection methods are often interfered with by cell substrates and are difficult to detect under high reflection, especially the overlap of substrates and defects. A solar cell defect detection method based on Fourier single-pixel imaging (FSI) is proposed to distinguish periodic substrates and defects in reconstruction by projecting illumination patterns with Fourier fringes, in which the removal of substrates reaches 100%. Meanwhile, for the high reflection present on the solar cell surface, the solar cell is directly treated as a single-pixel detector, which is free from interference from ambient light. The experiment adopts the solar cell itself as an imaging device under highly reflective conditions and removes the interference of the cell substrate by a 4-step phase-shifted FSI reconstruction algorithm to achieve the extraction of four types of defects, each of which is located in a different position of the solar cell substrate, at 10%, 50%, and 100% sampling rates. The method described here complements existing solar cell defect detection approaches and may be applied to enhance photovoltaic testers that rely on real-time correlation measurements, with promising applications in chip inspection and medical cell imaging. • Fourier single-pixel imaging(FSI) method for solar cells defect detection. • By using the solar cell as a photodetector(PD) to avoid the interference of high reflections. • Periodic substrate removal by 4-step phase-shift-based FSI reaches 100% in four different types of defects. [ABSTRACT FROM AUTHOR]

• This paper proposes an approach that uses single pixel imaging to obtain images with light interference removed for improving OCR recognition rate without image post-processing. • It is the first time that single pixel imaging is proposed to remove light interference for improving the character recognition rate to the best of the authors' knowledge. • When the character recognition rate of the picture obtained by traditional imaging is 0% by adding a serious interference pattern, the counterpart by single pixel imaging is 95.45%. Optical Character Recognition (OCR), which is generally based on figure recognition, is mainly effective for extracting text from pictures. However, it is a challenge to maintain a high recognition rate without being affected by light interference in a complicated environment. To reduce the light interference for improving the OCR recognition rate, this article proposes a method utilizing single-pixel imaging to obtain images without light interference for character recognition. Unlike the traditional CCD/CMOS-based imaging relying on image post-processing to eliminate interference, the method proposed without the need of any image post-processing which is a cumbersome process and often leads to a deterioration in the quality of the obtained images. Theoretical analysis shows that single-pixel imaging can eliminate the light interference in certain conditions completely. The verification experiments demonstrate that single-pixel imaging can only image the target and ignore an introduced highlighted stripe, whereas traditional CCD/CMOS-based imaging can not eliminate the effects of the stripe without image post-processing. Comparison experiments in contrast with the character recognition rate of the picture obtained from traditional imaging demonstrate the counterpart obtained from single-pixel imaging increased from 88.64% to 97.73%. The evaluation index of correlation and image quality illustrates that the picture obtained by single-pixel imaging has a higher correlation with the target picture and better image quality than the counterpart of the picture obtained from traditional imaging. When the character recognition rate of the picture obtained by traditional imaging is 0% by adding a serious interference pattern from a projector, the counterpart by single-pixel imaging is 95.45%. This approach provides a welcome boost to the development of the application of single-pixel imaging in character recognition by reducing the light interference, which provides a potential direction for the development of OCR to obtain higher recognition success rate under a complex environment. [ABSTRACT FROM AUTHOR]

Degradation of imaging quality due to noise sources is one of the most essential problems for single-pixel imaging (SPI). This paper presents a method that separates, identifies, and reduces noise from the 1-D signal of the SPI before reconstructing the image. The proposed method raises the quality of the picture significantly, for example, PSNR from 9.14 dB to 30.29 dB and SSIM from 5.55% to 91.99% when SNR is -15 dB in simulation. This method has a strong robustness to a variety of noise types compared to the traditional filtering methods. The experimental results verified the proposed method's feasibility and improved the image's quality from a chaotic state to an acceptable stage. The method proposed in this paper can separate, identify and remove the noise component from the sources in SPI, which may open a branch by removing noise from sources rather than post-processing. • A method to separate, identify, and reduce noise in single-pixel imaging. • Robust to a variety of noise types compared to the traditional filtering methods. • Enhance the imaging quality and expand application of SPI in noisy conditions. [ABSTRACT FROM AUTHOR]

• A deep-hole imaging method by using MMF is proposed. • Wavelet polarization fusion is applied to deep-hole image reconstruction. • The method achieves reconstruction with a maximum spatial resolution of 3.18 lp/mm. Conventional deep hole imaging uses a camera array as the imaging device, with the lens entering the deep hole to obtain spatial light information for reconstruction. The lens often determines the size of the imaging aperture and it is hard to adapt to different sizes of deep holes, especially elongated ones. This paper proposes a method of the multimode fiber(MMF) deep hole imaging based on wavelet polarization fusion, completed with fiber single-pixel imaging(FSPI) and fiber polarization single-pixel imaging(FPSPI). The system completes three different sizes of deep holes imaging, respectively 8mm × 8mm, 5mm × 5mm, 3mm × 3mm. In addition, the information entropy of each 32 pixels image increases 12.26 % and 11.78 % relative to the original image, which is higher than that of 64 pixels images of the same class, with the spatial resolution of 3.18 lp/mm. The proposed deep hole imaging method based MMF is expected to be applied in pipeline sidewall imaging and deep hole 3D imaging. [ABSTRACT FROM AUTHOR]

• We propose a single-pixel superposition compound eye (SPSCE) that deploys a photodetector which has no spatial resolution and imitates the rhabdom in natural organisms to deliver super-resolution imaging signal, which creates a new branch for the compound eyes. • SPSCE has the capacity to improve the imaging resolution two orders of magnitude than the number of ommatidia without subsequent image processing. • SPSCE has the unique super-robust character to capture whole acceptable images even if almost one-third of ommatidia are not working, and obtain images beyond the actual visual field of the target without observing directly. Deep understanding of biological superposition compound eye provides great opportunities in developing imaging systems with features beyond current planar detector array based imaging devices. However, artificial superposition compound eyes are designed on the basis of a planar detector array and that subsequently leads to the complex optical design and degradation of imaging quality inevitably. We propose a single-pixel superposition compound eye (SPSCE), whose imaging resolution has been improved two orders of magnitude than the number of ommatidia without subsequent image processing. SPSCE has the ability to capture the whole acceptable image of objects even if almost one-third of ommatidia at random positions are not working, which makes it possible to operate reliably even in the damaged state. SPSCE has the capacity to image beyond the actual visual field of the target without observing directly. With only one lateral sub-eye working and deviating from the visual field of the target by 20. 41 ∘ , SPSCE obtains the complete and recognizable image of the target independently through the diffuse reflection optical information of the surrounding environment. The unique super-robust character of SPSCE with its super-resolution property contributes to developing anti-interference artificial compound eyes, unlocking the limit toward development of much higher imaging resolution artificial superposition compound eyes. [ABSTRACT FROM AUTHOR]