Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatm...Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.展开更多
A method of fabricating multi-core polymer image fiber is proposed.Image fiber preform is fabricated by stacking thousands of polymer fibers each with a 0.25-mm diameter orderly in a die by only one step.The preform i...A method of fabricating multi-core polymer image fiber is proposed.Image fiber preform is fabricated by stacking thousands of polymer fibers each with a 0.25-mm diameter orderly in a die by only one step.The preform is heated and stretched into image fiber with an outer diameter of 2mm.Then a portable eyewear-style three-dimensional(3D) endoscope system is designed,fabricated,and characterized.This endoscopic system is composed of two graded index lenses,two pieces of 0.35-m length image guide fibers,and a pair of oculars.It shows good ?exibility and portability,and can provide the depth information accordingly.展开更多
Brillouin imaging(BI)for micromechanical characterization of tisues and biomaterials is a fast-developing field of research with a strong potential for medical diagnosis of disease-modified tissues and cells.Although ...Brillouin imaging(BI)for micromechanical characterization of tisues and biomaterials is a fast-developing field of research with a strong potential for medical diagnosis of disease-modified tissues and cells.Although the principles of BI imply its compatibility with in vivo and in situ measurements,the integntion of BI with a flexible catheter,capable of reaching the region of interest within the body,is yet to be reported.Here,for the first time,we experimentally investigate integration of the Brillouin spectroscope with standard optical fber components to achieve a Brillouin endoscope.The performance of single-fiber and dual-fiber endoscopes are demonstrated and analyzed.We show that a major challenge in construction of Bri louin endoscopes is the strong backward Brillouin scattering in the optical fiber and we present a dual-fiber geometry as a possible solution.Measurements of Brillouin spectra in test liquids(water,ethanol and glyoerol)ane demonstrated using the dual-fiber endoscope and its performance is analyzed numerically with the help of a beam propagation model.展开更多
The most important optical component in an optical fiber endoscope is its objective lens.To achieve a high imaging performance level,the development of an ultra-compact objective lens is thus the key to an ultra-thin ...The most important optical component in an optical fiber endoscope is its objective lens.To achieve a high imaging performance level,the development of an ultra-compact objective lens is thus the key to an ultra-thin optical fiber endoscope.In this work,we use femtosecond laser 3D printing to develop a series of micro objective lenses with different optical designs.The imaging resolution and field-of-view performances of these printed micro objective lenses are investigated via both simulations and experiments.For the first time,multiple micro objective lenses with different fields of view are printed on the end face of a single imaging optical fiber,thus realizing the perfect integration of an optical fiber and objective lenses.This work demonstrates the considerable potential of femtosecond laser 3D printing in the fabrication of micro-optical systems and provides a reliable solution for the development of an ultrathin fiber endoscope.展开更多
We present an Er-doped fiber(Er:fiber)-based femtosecond laser at 780 nm with 256 MHz repetition rate, 191 fs pulse duration, and over 1 W average power.Apart from the careful third-order dispersion management, we int...We present an Er-doped fiber(Er:fiber)-based femtosecond laser at 780 nm with 256 MHz repetition rate, 191 fs pulse duration, and over 1 W average power.Apart from the careful third-order dispersion management, we introduce moderate self-phase modulation to broaden the output spectrum of the Er:fiber amplifier and achieve 193 fs pulse duration and 2.43W average power.Over 40% frequency doubling efficiency is obtained by a periodically poled lithium niobate crystal.Delivering through a hollow-core photonic bandgap fiber, this robust laser becomes an ideal and convenient light source for two-photon autofluorescence imaging.展开更多
Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to...Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to control beam profiles,but the spacer length should be well controlled to obtain desired beam profiles and thus it sets an obstacle in mass catheter fabrication.Besides,although GRIN lens with large gradient constant can provide tight focus spot,it has short depth of focus and fast-expanded beam which leads to poor lateral resolution for deep tissue.In this paper,a type of spacer-removed probe is demonstrated with a small gradient constant GRIN lens.This design simplifies the fabrica-tion process and is suitable for mass production.The output beam of the catheter is a narrow nearly collimated light beam,referred to as pencil beam here.The full width at half maximum beam size varies from 35.1μm to 75.3μm in air over 3-mm range.Probe design principles are elaborated with probe/catheter fabrication and performance test.The in vivo imaging of the catheter was verified by a clinical ICOCT system.Those results prove that this novel pencil-beam scanning catheter is potentially a good choice for ICOCT systems.展开更多
基金supported by National Natural Science Foundation of China(62135007 and 61925502).
文摘Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61275106 and 61275086)
文摘A method of fabricating multi-core polymer image fiber is proposed.Image fiber preform is fabricated by stacking thousands of polymer fibers each with a 0.25-mm diameter orderly in a die by only one step.The preform is heated and stretched into image fiber with an outer diameter of 2mm.Then a portable eyewear-style three-dimensional(3D) endoscope system is designed,fabricated,and characterized.This endoscopic system is composed of two graded index lenses,two pieces of 0.35-m length image guide fibers,and a pair of oculars.It shows good ?exibility and portability,and can provide the depth information accordingly.
基金support provided through Imperial College Research Fellowship Scheme (G53037).
文摘Brillouin imaging(BI)for micromechanical characterization of tisues and biomaterials is a fast-developing field of research with a strong potential for medical diagnosis of disease-modified tissues and cells.Although the principles of BI imply its compatibility with in vivo and in situ measurements,the integntion of BI with a flexible catheter,capable of reaching the region of interest within the body,is yet to be reported.Here,for the first time,we experimentally investigate integration of the Brillouin spectroscope with standard optical fber components to achieve a Brillouin endoscope.The performance of single-fiber and dual-fiber endoscopes are demonstrated and analyzed.We show that a major challenge in construction of Bri louin endoscopes is the strong backward Brillouin scattering in the optical fiber and we present a dual-fiber geometry as a possible solution.Measurements of Brillouin spectra in test liquids(water,ethanol and glyoerol)ane demonstrated using the dual-fiber endoscope and its performance is analyzed numerically with the help of a beam propagation model.
基金This work was supported by Shenzhen Science and Technology Program(RCYX20200714114524139,Shenzhen Key Laboratory of Ultrafast Laser Micro/Nano Manufacturing ZDSYS20220606100405013)Natural Science Foundation of Guangdong Province(2022B1515120061)National Natural Science Foundation of China(62122057,62075136).
文摘The most important optical component in an optical fiber endoscope is its objective lens.To achieve a high imaging performance level,the development of an ultra-compact objective lens is thus the key to an ultra-thin optical fiber endoscope.In this work,we use femtosecond laser 3D printing to develop a series of micro objective lenses with different optical designs.The imaging resolution and field-of-view performances of these printed micro objective lenses are investigated via both simulations and experiments.For the first time,multiple micro objective lenses with different fields of view are printed on the end face of a single imaging optical fiber,thus realizing the perfect integration of an optical fiber and objective lenses.This work demonstrates the considerable potential of femtosecond laser 3D printing in the fabrication of micro-optical systems and provides a reliable solution for the development of an ultrathin fiber endoscope.
基金supported in part by the National Natural Science Foundation of China(Nos.61475008and 31327901)
文摘We present an Er-doped fiber(Er:fiber)-based femtosecond laser at 780 nm with 256 MHz repetition rate, 191 fs pulse duration, and over 1 W average power.Apart from the careful third-order dispersion management, we introduce moderate self-phase modulation to broaden the output spectrum of the Er:fiber amplifier and achieve 193 fs pulse duration and 2.43W average power.Over 40% frequency doubling efficiency is obtained by a periodically poled lithium niobate crystal.Delivering through a hollow-core photonic bandgap fiber, this robust laser becomes an ideal and convenient light source for two-photon autofluorescence imaging.
基金financial supports from the National Natural Science Foundation of China(Grant No.81927805)Shenzhen Municipal Science and Technology Plan Project,China(Grant No.JCYJ20160427183803458)。
文摘Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to control beam profiles,but the spacer length should be well controlled to obtain desired beam profiles and thus it sets an obstacle in mass catheter fabrication.Besides,although GRIN lens with large gradient constant can provide tight focus spot,it has short depth of focus and fast-expanded beam which leads to poor lateral resolution for deep tissue.In this paper,a type of spacer-removed probe is demonstrated with a small gradient constant GRIN lens.This design simplifies the fabrica-tion process and is suitable for mass production.The output beam of the catheter is a narrow nearly collimated light beam,referred to as pencil beam here.The full width at half maximum beam size varies from 35.1μm to 75.3μm in air over 3-mm range.Probe design principles are elaborated with probe/catheter fabrication and performance test.The in vivo imaging of the catheter was verified by a clinical ICOCT system.Those results prove that this novel pencil-beam scanning catheter is potentially a good choice for ICOCT systems.