Miniaturized omnidirectional flexible side-view endoscope for rapid monitoring of thin tubular biostructures

Design methodology for catadioptric zoom panoramic optical systems based on image plane bending matched correction

Zoom panoramic optical systems incorporate a panoramic peripheral vision zoom imaging function, enabling swift wide-area coarse and localized precise detection. These systems find applicability in examining pipes and other internal structures. This study centers on the catadioptric zoom panoramic optical system and its associated optical design method. A mathematical model of the front mirror was formulated based on the imaging relationship. Subsequently, the bending of the image plane of the front mirror was computed and simplified through curve fitting. The object surface bending of the zoom subsystem was established correspondingly, leveraging the solution for the mirror bending curve matched correction, culminating in deriving the initial structure of the zoom. Integrating the front mirror and zoom subsystems facilitated the comprehensive design realization of the catadioptric zoom panoramic optical system. A catadioptric zoom panoramic optical system was designed to validate the proposed design method. This study introduces a novel, to the best of our knowledge, conceptual approach to crafting catadioptric zoom panoramic optical systems.

Toward next-generation endoscopes integrating biomimetic video systems, nonlinear optical microscopy, and deep learning

According to the World Health Organization, the proportion of the world's population over 60 years will approximately double by 2050. This progressive increase in the elderly population will lead to a dramatic growth of age-related diseases, resulting in tremendous pressure on the sustainability of healthcare systems globally. In this context, finding more efficient ways to address cancers, a set of diseases whose incidence is correlated with age, is of utmost importance. Prevention of cancers to decrease morbidity relies on the identification of precursor lesions before the onset of the disease, or at least diagnosis at an early stage. In this article, after briefly discussing some of the most prominent endoscopic approaches for gastric cancer diagnostics, we review relevant progress in three emerging technologies that have significant potential to play pivotal roles in next-generation endoscopy systems: biomimetic vision (with special focus on compound eye cameras), non-linear optical microscopies, and Deep Learning. Such systems are urgently needed to enhance the three major steps required for the successful diagnostics of gastrointestinal cancers: detection, characterization, and confirmation of suspicious lesions. In the final part, we discuss challenges that lie en route to translating these technologies to next-generation endoscopes that could enhance gastrointestinal imaging, and depict a possible configuration of a system capable of (i) biomimetic endoscopic vision enabling easier detection of lesions, (ii) label-free in vivo tissue characterization, and (iii) intelligently automated gastrointestinal cancer diagnostic.

Calibration of a Catadioptric System and 3D Reconstruction Based on Surface Structured Light

In response to the problem of the small field of vision in 3D reconstruction, a 3D reconstruction system based on a catadioptric camera and projector was built by introducing a traditional camera to calibrate the catadioptric camera and projector system. Firstly, the intrinsic parameters of the camera and the traditional camera are calibrated separately. Then, the calibration of the projection system is accomplished by the traditional camera. Secondly, the coordinate system is introduced to calculate, respectively, the position of the catadioptric camera and projector in the coordinate system, and the position relationship between the coordinate systems of the catadioptric camera and the projector is obtained. Finally, the projector is used to project the structured light fringe to realize the reconstruction using a catadioptric camera. The experimental results show that the reconstruction error is 0.75 mm and the relative error is 0.0068 for a target of about 1 m. The calibration method and reconstruction method proposed in this paper can guarantee the ideal geometric reconstruction accuracy.

High-performance compact athermal panoramic annular lens design with separated radial optical power

A panoramic annular lens can provide abundant spatial information in real time with its compact and scalable structure. To deal with extreme temperature environments and to improve the utilization of an image plane, we propose a high-performance compact athermal panoramic annular lens with separated radial optical power. By introducing multiple free-form surfaces, the system achieves a field of view of (40^∘∼100^∘)×360^∘, an f-number of 2.2, and a total length of 40 mm. The modulation transfer function of the system's full fields of view is greater than 0.5 at 200 lp/mm, and the distortion is less than 2.5%. It can work stably in the range of -30^∘C to 70°C. The proposed system is compact, athermal, and high-performing and has broad application prospects in the fields of visual positioning and biomedicine.

Design and implementation of a high-performance panoramic annular lens

In this work, a high-performance panoramic annular lens system designed with a point-by-point method and variable parameter optimization strategies is proposed. Due to the optimization and design, the system maintains a balance among characteristic parameters and can achieve a 360^∘×(40^∘-95^∘) field of view with a 4.34 mm focal length, an f-number of 4.5, and an F-θ distortion of less than 0.5%. Experimental results verify the parameters and demonstrate that the distortion is less than 0.8%, except in some areas with mechanical damage on the ogive surface.

Endoscopic Optical Imaging Technologies and Devices for Medical Purposes: State of the Art

The growth and development of optical components and, in particular, the miniaturization of micro-electro-mechanical systems (MEMSs), has motivated and enabled researchers to design smaller and smaller endoscopes. The overarching goal of this work has been to image smaller previously inaccessible luminal organs in real time, at high resolution, in a minimally invasive manner that does not compromise the comfort of the subject, nor introduce additional risk. Thus, an initial diagnosis can be made, or a small precancerous lesion may be detected, in a small-diameter luminal organ that would not have otherwise been possible. Continuous advancement in the field has enabled a wide range of optical scanners. Different scanning techniques, working principles, and the applications of endoscopic scanners are summarized in this review.

Artificial compound eye-tipped optical fiber for wide field illumination

In this Letter, we present a novel, to the best of our knowledge, component with beam delivering and wide field beam homogenizing functions by grafting an artificial compound eye (ACE) micro-structure onto the polymer optical fiber (POF) end face. The 3D ACE mold is fabricated by femtosecond laser-assisted micro machining, and the ACE micro-structure is transferred onto the end face through high accuracy nano-imprinting. The resultant POF end face integrates over 400 spherical micro-lenses, enabling a 40% enhancement in both the acceptance angle and the effective numerical aperture. Meanwhile, the integrated ommatidia array serves as an outstanding beam homogenizer, shaping the output beam into quasi flat-top distribution, which demonstrates promise in wide field homogeneous illumination, by reflection and transmission imaging experiments in both visible and near infrared bands.