Light-sheet fluorescence microscopy (LSFM) is a powerful tool for biological studies because it allows for optical sectioning of dynamic samples with superior temporal resolution. However, LSFM using 2 orthogonally co-aligned objectives requires a special sample geometry, and volumetric imaging speed is limited due to physical sample translation. This paper describes an oblique scanning 2-photon LSFM (OS-2P-LSFM) that eliminates these limitations by using a single objective near the sample and a refractive scanning-descanning system. This system also provides improved light-sheet confinement against scattering by using a 2-photon Bessel beam. The OS-2P-LSFM hold promise for studying structural, functional and dynamic aspects of living tissues and organisms because it allows for high-speed, translation-free and scattering-robust 3D imaging of large biological specimens.

Capsule endoscopes require a high-quality imaging system in terms of the wide field of view (FOV), image brightness, and resolution to provide accurate diagnostic information. However, because of the wide-angle lens design, the first element of the lens inevitably becomes larger in diameter, making it difficult to reduce the overall size of the lens. In this study, the compact wide-angle lens for a capsule endoscope is reported. The proposed system allows the first element to be compact in diameter and increases image quality by utilizing all aspheric surfaces for optical aberration control. The specification of the proposed capsule endoscope lens shows the wide FOV of 160 deg, F-number 2.8, and total track length of 5 mm. In the overall FOV, relative illumination is still over 60%. To achieve a high image quality in the proposed system, the modulation transfer function is over 30% at 180 lp/mm for a 1920 × 1080 1/6 inch CMOS image sensor in a pixel size of 1.4 µm.

In the past few decades, video endoscopy has become one of the primary medical devices in diverse clinical fields for examination, treatment, and early disease diagnosis of the gastrointestinal tract. For an accurate diagnosis, an endoscopic camera offering bright and wide field-of-view images is required while maintaining its compact dimensions to enter the long, narrow, and dark tract inside of the body. Recent endoscopic lenses successfully provide wide fields-of-view and have compact sizes for the system; however, their f-numbers still remain at 2.8 or higher. Therefore, further improvement in f-numbers is required to compensate for the restricted illumination system of the endoscopic probe. Here, we present a low f-number endoscopic lens design while providing wide field-of-view and high-resolution imaging. The proposed lens system achieved a low f-number of 2.2 and a field-of-view of 140 deg. The modulation transfer function (MTF) is over 20% at 180 lp/mm, and relative illumination is more than 60% in the full field. Additionally, the proposed lens is designed for a 1/4” 5-megapixel complementary metal-oxide-semiconductor (CMOS) image sensor with a pixel size of 1.4 µm. This all-plastic lens design could help develop a high-performance disposable endoscope that prevents the risk of infection or cross-contamination with mass manufacture and low cost.

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