Objective: To compare patient-reported outcomes after implantation of the ZA9003 intraocular lens(IOLs), or the MCX11 ASP IOLs or the spherical IOLs(HQ-201HEP). Methods: Prospective nonrandomized controlled trial was ...Objective: To compare patient-reported outcomes after implantation of the ZA9003 intraocular lens(IOLs), or the MCX11 ASP IOLs or the spherical IOLs(HQ-201HEP). Methods: Prospective nonrandomized controlled trial was used. A total of 105 patients(210 eyes) were divided into three groups according to the type of IOLs: ZA9003(35 patients, 70 eyes), MCX11 ASP(35 patients, 70 eyes) or HQ-201HEP(35 patients, 70 eyes). The main outcome was scores of Catquest nine-item short-form questionnaire. Additional outcome was best corrected visual acuities, spherical aberration(SA) and total higher-order aberrations(HOAs). Results: The global score was significantly lower in the spherical IOL group than the aspherical IOL group of-020 μm SA(P < 0.05) and the aspherical IOL group of-027 μm SA(P < 0.05), and no significant difference was found in the global score between the aspherical IOL group of-020 μm SA than the aspherical IOL group of-027 μm SA(P > 0.05). Significant differences were also found in question 2, question 5, question 6 and question 8 between the spherical IOLs and the aspherical IOLs. Conclusion: Implantation of an aspherical IOL could improve vision-related quality of life compared with a spherical IOL. However, there were no statistically significant differences in vision-related quality of life between aspheric IOLs with different negative spherical aberrations.展开更多
In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive ...In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.展开更多
In this paper, we study the effect of spherical aberrations on the light intensity and the temperature distribution in the focal region in a 250-kHz femtosecond laser irradiated Ag^＋-doped borosilicate glass. When a ...In this paper, we study the effect of spherical aberrations on the light intensity and the temperature distribution in the focal region in a 250-kHz femtosecond laser irradiated Ag^＋-doped borosilicate glass. When a focused beam goes through an interface between air and glass, spherical aberration will result in the separation of the focal point and then cause a clear change of the light intensity distribution along the incident direction. That phenomenon will further influence the longitudinal cross-section temperature distribution in glass. Here we use Ag nanoparticle formation as a marker for establishing temperature distribution and we find that the formation of nanoparticle shows a strong dependence on the temperature field and the detailed precipitation process is also discussed.展开更多
Based on a 4f system,a 0?reflector and a single laser diode side-pump amplifier,a new amplifier is designed to compensate the spherical aberration of the amplified laser generated by a single laser diode side-pump amp...Based on a 4f system,a 0?reflector and a single laser diode side-pump amplifier,a new amplifier is designed to compensate the spherical aberration of the amplified laser generated by a single laser diode side-pump amplifier and enhance the power of the amplified laser.Furthermore,the role of the 4f system in the passive spherical aberration compensation and its effect on the amplified laser are discussed in detail.The results indicate that the amplification efficiency is enhanced by incorporating a 4f system in a double-pass amplifier and placing a 0?reflector only at the focal point of the single-pass amplified laser.This method also effectively uses the heat from the gain medium(neodymiumdoped yttrium aluminium garnet)of the amplifier to compensate the spherical aberration of the amplified laser.展开更多
We investigate the generation of single-transverse-mode Laguerre-Gaussian(LG)emission from a diode-end-pumped Nd:YVO_(4),1064 nm laser using mode selection via intracavity spherical aberration(SA).We present both theo...We investigate the generation of single-transverse-mode Laguerre-Gaussian(LG)emission from a diode-end-pumped Nd:YVO_(4),1064 nm laser using mode selection via intracavity spherical aberration(SA).We present both theoretical and experimental investigations,examining the limits of the order(both radial and angular indices)of the LG modes which can be produced,along with the resultant output power.We found that in order to generate single-mode emission of low-order LG modes which have relatively small beam diameters,lenses with shorter focal-length were required(to better differentiate neighboring LG modes via SA).The converse was true of LG modes with high-order.Through appropriate choice of the focal length of the intracavity lens,we were able to generate single-mode,LG_(0,±m) laser output with angular indices m selectable from 1 to 95,as well as those with non-zero radial indices p of up to 4.展开更多
AIM：To study the relation between higher-order aberrations（HOAs）and contrast sensitivity（CS）in normal eyes among a population of laser in situ keratomileusis（LASIK）candidates.METHODS：In 6629 eyes of 3315 LASIK...AIM：To study the relation between higher-order aberrations（HOAs）and contrast sensitivity（CS）in normal eyes among a population of laser in situ keratomileusis（LASIK）candidates.METHODS：In 6629 eyes of 3315 LASIK candidates,CS were measured under dark environment at the spatial frequencies of 1.5,3,6,12 and 18 cycles per degree（c/d）,respectively,using an Optec 6500 visual function tester.Meanwhile,ocular HOAs were measured for a 6.0 mm pupil with a Hartmann-Shack wavefront analyzer.RESULTS：In the study,the subjects with an average spherical equivalent of-4.86±2.07 D were included.HOAs decreased from the third to the sixth order aberrations with predominant aberrations of third-order coma,trefoil and fourth-order spherical aberration.At low and moderate spatial frequencies,CS was negatively correlated with the third-order coma and trefoil aberrations,and decreased with increasing Z31,but increased with increasing Z3-3and Z5-1.At high spatial frequencies,CS decreased with increasing Z3-3and increased with increasing Z5-1.CONCLUSION：At a large pupil size of 6.0 mm,the thirdorder aberrations,but not the total aberrations,are the main factors affecting CS.Vertical coma is negatively correlated with CS.展开更多
In most textbooks, lens aberrations are usually described in the briefest possible manner, without any attempt for their proper derivation. At the same time, monographs which do go into more detail are often inaccessi...In most textbooks, lens aberrations are usually described in the briefest possible manner, without any attempt for their proper derivation. At the same time, monographs which do go into more detail are often inaccessible to most students and non-specialists interested in deeper understanding of this topic. This article tries to fill this gap and provide an introduction to what happens when basic formulas of Geometrical Optics are extended by third-order terms in Taylor’s expansion of sin (<span style="white-space:nowrap;">α). The presentation is accessible to most undergraduate students as it requires only some knowledge of basic calculus and planar geometry. The resulting five aberrations are then described in detail, including a novel derivation of the exact shape of coma. A simple Mathematica program is included to facilitate numerical exploration of the magnitude of the resulting aberrations for various optical systems.展开更多
The technique of optical tweezers has been improved a lot since its invention, which extends the application fields of optical tweezers. Besides the conventionally used Gaussian beams, different types of ring beams ha...The technique of optical tweezers has been improved a lot since its invention, which extends the application fields of optical tweezers. Besides the conventionally used Gaussian beams, different types of ring beams have also been used to form optical tweezers for different purposes. The two typical kinds of ring beams used in optical tweezers are the hollow Gaussian beam and Laguerre-Gaussian （LG） beam. Both theoretical computation and experiments have shown that the axial trapping force is improved for the ring beams compared with the Gaussian beam, and hence the trapping stability is improved, although the transverse trapping forces of ring beams are smaller than that of Gaussian beam. However, no systematic study on the trapping forces of ring beam has ever been discussed. In this article, we will investigate the axial and transverse trapping forces of different types of ring beams with different parameters systematically, by numerical computation in which the ray optics model is adopted. The spherical aberration caused by the refractive index mismatch between oil and water is also considered in the article. The trapping forces for different objectives that obey the sine condition and tangent condition are also compared with each other. The result of systematical calculation will be useful for the applications of optical tweezers formed by different types of ring beams.展开更多
AIM:To investigate the size of functional optical zone(FOZ)after small incision lenticule extraction(SMILE)versus femtosecond laser assisted excimer laser keratomileusis(FS-LASIK)for myopia correction and potential as...AIM:To investigate the size of functional optical zone(FOZ)after small incision lenticule extraction(SMILE)versus femtosecond laser assisted excimer laser keratomileusis(FS-LASIK)for myopia correction and potential associated factors for FOZ.METHODS:A total of 133 patients who received corneal refractive surgery in our hospital between November 2018 and July 2021 were retrospectively enrolled.There were 63 patients(123 eyes)in SMILE group and 70patients(139 eyes)in FS-LASIK group.The size of FOZ was measured using Pentacam 3-dementional anterior segment analyzer before and 3mo after surgery,so as to analyze postoperative achieved functional optical zone(AFOZ)and its contributing parameters.RESULTS:When planned functional optical zone(PFOZ)was 6.5 mm for both groups,AFOZ was 1.45±0.27 and 1.67±0.25 mm smaller than preoperative FOZ in SMILE group and FS-LASIK group 3mo after surgery.AFOZ in SMILE group was significantly larger than that in FS-LASIK group(P<0.001).Variation of FOZ was negatively correlated with preoperative spherical equivalent(SE)and positively correlated with variation of mean keratometry value(△Km),variation of spherical aberration(△SA),and variation of Q-value(△Q,all P<0.001)in both groups.Multiple variable linear regression equations were△FOZ=1.354-0.1×pre-SE+0.336×△Q+1.462×△SA in SMILE group and△FOZ=1.512+0.137×△Q+0.468×△SA in FS-LASIK group.CONCLUSION:AFOZ is significantly smaller than preoperative FOZ in both SMILE and FS-LASIK groups.With the same PFOZ,larger AFOZ is achieved in SMILE group than in FS-LASIK group.展开更多
We conduct several experiments to further clarify the formation mechanism of a self-organized void array induced by a single laser beam, including energy-related experiments, refractive-index-contrast-related experime...We conduct several experiments to further clarify the formation mechanism of a self-organized void array induced by a single laser beam, including energy-related experiments, refractive-index-contrast-related experiments, depth-related ex- periments, and effective-numerical-aperture experiment. These experiments indicate that the interface spherical aberration is indeed responsible for the formation of void arrays.展开更多
The complex amplitude distribution which can compensate for the spherical aberration caused by mismatch on lnterthce between recording material and immersion material （air） on three-dimensional optical storage syste...The complex amplitude distribution which can compensate for the spherical aberration caused by mismatch on lnterthce between recording material and immersion material （air） on three-dimensional optical storage system is derived analytically and numerically. Comparison between two approaches is made. It is also shown how the depth of recording layer and position of reference plane are related to the phase distribution at reference plane and how the mismatch can be resolved by using a pure phase element.展开更多
Purposes:To evaluate the impact of coronavirus disease 2019(COVID-19)on postoperative visual acuity,optical quality,and severity of dry eye disease in patients after small incision lenticule extraction(SMILE).Methods:...Purposes:To evaluate the impact of coronavirus disease 2019(COVID-19)on postoperative visual acuity,optical quality,and severity of dry eye disease in patients after small incision lenticule extraction(SMILE).Methods:This is a retrospective,comparative study.Patients who underwent SMILE were included and divided into two groups according to the period at the eye center of the Second Affiliated Hospital of Zhejiang University.The first group included patients who underwent SMILE before the large-scale COVID-19 pandemic in China(Group 1).The second group comprised patients who underwent SMILE during the pandemic with a confirmed infection of COVID-19(Group 2).The visual acuity,the severity of dry eye,ocular surface disease index(OSDI),oculus keratography analysis,and individual Zernike coefficients were evaluated and compared between the 2 groups.Results:A total of 43 eyes of 23 patients and 45 eyes of 26 patients were included in Groups 1 and 2,respectively.The OSDI score in Group 2 was significantly higher than Group 1(P<0.01).The corrected distance visual acuity(CDVA,logMAR)at 3 months postoperatively in Group 1 was better than in Group 2(P<0.001).Despite the improvement over 1 month after the COVID-19 infection,the OSDI score was still higher in Group 2 than in Group 1(P<0.01).The bulbar and limbal redness were significantly higher in Group 2 than in Group 1 at both 1 month and 3 months(P<0.05),while no significant differences were found in tear breakup time or tear meniscus height.Spherical aberration(SA)at the 4 mm zone was significantly higher in Group 2 than in Group 1 both at 1 month and 3 months(P<0.001),while no significant changes were observed in corneal total higher-order aberrations.No significant correlation was found between the bulbar/limbal redness index and SA.Conclusions:COVID-19 infection impaired visual outcomes and aggravated dry eye severity among postoperative SMILE patients.展开更多
In this Letter,we present a low-cost,high-resolution spectrometer design for ultra-high resolution optical coherence tomography(UHR-OCT),in which multiple standard achromatic lenses are combined to replace the expensi...In this Letter,we present a low-cost,high-resolution spectrometer design for ultra-high resolution optical coherence tomography(UHR-OCT),in which multiple standard achromatic lenses are combined to replace the expensive F-theta lens to achieve a comparable performance.For UHR-OCT,the spectrometer plays an important role in high-quality 3D image reconstruction.Typically,an F-theta lens is used in spectrometers as the Fourier lens to focus the dispersed light on the sensor array,and this F-theta lens is one of the most expensive components in spectrometers.The advantage of F-theta lens over the most widely used achromatic lens is that the aberrations(mainly spherical aberration,SA)are corrected,so the foci of the dispersed optical beams(at different wavelengths)with different incident angles could be placed on the sensor array simultaneously.For the achromatic lens,the foci of the center part of the spectrum are farther than those on the side in the longitudinal direction,causing degradations of the spectral resolution.Furthermore,in comparison with the achromatic lens with the same focal length,those with smaller diameters have stronger SA,but small lenses are what we need for making spectrometers compact and stable.In this work,we propose a simple method of using multiple long-focal-length achromatic lenses together to replace the F-theta lens,which is>8-fold cheaper based on the price of optical components from Thorlabs,US.Both simulations and in vivo experiments were implemented to demonstrate the performance of the proposed method.展开更多
The electron gun with rotational surface cathode is presented to improve the laminarity of the converging electron beams in this paper,and the function expression of the rotational surfaces is given.The results of par...The electron gun with rotational surface cathode is presented to improve the laminarity of the converging electron beams in this paper,and the function expression of the rotational surfaces is given.The results of particle in cell(PIC)simulation indicate that anode-hole spherical aberration is the major cause for the nonlaminarity of the electron beams.By properly choosing the size of the shape,rotational surface cathode can effectively counteract the effect of the anode-hole spherical aberration and enhance the laminarity of the electron beams.The theoretical analysis was carried out for the explanation of the phenomenon that appeared in the PIC simulation.展开更多
基金supported by the Health Bureau of Shanghai City(201440029)
文摘Objective: To compare patient-reported outcomes after implantation of the ZA9003 intraocular lens(IOLs), or the MCX11 ASP IOLs or the spherical IOLs(HQ-201HEP). Methods: Prospective nonrandomized controlled trial was used. A total of 105 patients(210 eyes) were divided into three groups according to the type of IOLs: ZA9003(35 patients, 70 eyes), MCX11 ASP(35 patients, 70 eyes) or HQ-201HEP(35 patients, 70 eyes). The main outcome was scores of Catquest nine-item short-form questionnaire. Additional outcome was best corrected visual acuities, spherical aberration(SA) and total higher-order aberrations(HOAs). Results: The global score was significantly lower in the spherical IOL group than the aspherical IOL group of-020 μm SA(P < 0.05) and the aspherical IOL group of-027 μm SA(P < 0.05), and no significant difference was found in the global score between the aspherical IOL group of-020 μm SA than the aspherical IOL group of-027 μm SA(P > 0.05). Significant differences were also found in question 2, question 5, question 6 and question 8 between the spherical IOLs and the aspherical IOLs. Conclusion: Implantation of an aspherical IOL could improve vision-related quality of life compared with a spherical IOL. However, there were no statistically significant differences in vision-related quality of life between aspheric IOLs with different negative spherical aberrations.
文摘In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.
基金supported by the National Natural Science Foundation of China (Grant No.60908007)the Shanghai Leading Academic Discipline Project,China (Grant No.S30105)
文摘In this paper, we study the effect of spherical aberrations on the light intensity and the temperature distribution in the focal region in a 250-kHz femtosecond laser irradiated Ag^＋-doped borosilicate glass. When a focused beam goes through an interface between air and glass, spherical aberration will result in the separation of the focal point and then cause a clear change of the light intensity distribution along the incident direction. That phenomenon will further influence the longitudinal cross-section temperature distribution in glass. Here we use Ag nanoparticle formation as a marker for establishing temperature distribution and we find that the formation of nanoparticle shows a strong dependence on the temperature field and the detailed precipitation process is also discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.62075056 and 61927815)the Natural Science Foundation of Hebei Province(Grant Nos.F2023202082 and F2022202035)。
文摘Based on a 4f system,a 0?reflector and a single laser diode side-pump amplifier,a new amplifier is designed to compensate the spherical aberration of the amplified laser generated by a single laser diode side-pump amplifier and enhance the power of the amplified laser.Furthermore,the role of the 4f system in the passive spherical aberration compensation and its effect on the amplified laser are discussed in detail.The results indicate that the amplification efficiency is enhanced by incorporating a 4f system in a double-pass amplifier and placing a 0?reflector only at the focal point of the single-pass amplified laser.This method also effectively uses the heat from the gain medium(neodymiumdoped yttrium aluminium garnet)of the amplifier to compensate the spherical aberration of the amplified laser.
基金National Natural Science Foundation of China(61975146&62075159)Major Scientific and Technological Innovation Projects of Key R&D Plans in Shandong Province(2019JZZY020206)+2 种基金Takashige Omatsu acknowledges support from KAKENHI Grants-in-Aid(Nos.JP18H03884)of the Japan Society for the Promotion of Science(JSPS)the Core Research for Evolutional Science and Technology program(No.JPMJCR1903)of the Japan Science and Technology Agency(JST)Sijia Wang acknowledges support from Foundation for Distinguished Young Scholars of China Academy of Space Technology(2021).
文摘We investigate the generation of single-transverse-mode Laguerre-Gaussian(LG)emission from a diode-end-pumped Nd:YVO_(4),1064 nm laser using mode selection via intracavity spherical aberration(SA).We present both theoretical and experimental investigations,examining the limits of the order(both radial and angular indices)of the LG modes which can be produced,along with the resultant output power.We found that in order to generate single-mode emission of low-order LG modes which have relatively small beam diameters,lenses with shorter focal-length were required(to better differentiate neighboring LG modes via SA).The converse was true of LG modes with high-order.Through appropriate choice of the focal length of the intracavity lens,we were able to generate single-mode,LG_(0,±m) laser output with angular indices m selectable from 1 to 95,as well as those with non-zero radial indices p of up to 4.
文摘AIM：To study the relation between higher-order aberrations（HOAs）and contrast sensitivity（CS）in normal eyes among a population of laser in situ keratomileusis（LASIK）candidates.METHODS：In 6629 eyes of 3315 LASIK candidates,CS were measured under dark environment at the spatial frequencies of 1.5,3,6,12 and 18 cycles per degree（c/d）,respectively,using an Optec 6500 visual function tester.Meanwhile,ocular HOAs were measured for a 6.0 mm pupil with a Hartmann-Shack wavefront analyzer.RESULTS：In the study,the subjects with an average spherical equivalent of-4.86±2.07 D were included.HOAs decreased from the third to the sixth order aberrations with predominant aberrations of third-order coma,trefoil and fourth-order spherical aberration.At low and moderate spatial frequencies,CS was negatively correlated with the third-order coma and trefoil aberrations,and decreased with increasing Z31,but increased with increasing Z3-3and Z5-1.At high spatial frequencies,CS decreased with increasing Z3-3and increased with increasing Z5-1.CONCLUSION：At a large pupil size of 6.0 mm,the thirdorder aberrations,but not the total aberrations,are the main factors affecting CS.Vertical coma is negatively correlated with CS.
文摘In most textbooks, lens aberrations are usually described in the briefest possible manner, without any attempt for their proper derivation. At the same time, monographs which do go into more detail are often inaccessible to most students and non-specialists interested in deeper understanding of this topic. This article tries to fill this gap and provide an introduction to what happens when basic formulas of Geometrical Optics are extended by third-order terms in Taylor’s expansion of sin (<span style="white-space:nowrap;">α). The presentation is accessible to most undergraduate students as it requires only some knowledge of basic calculus and planar geometry. The resulting five aberrations are then described in detail, including a novel derivation of the exact shape of coma. A simple Mathematica program is included to facilitate numerical exploration of the magnitude of the resulting aberrations for various optical systems.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 20273065 and 10474094） and ‘the Knowledge Innovation Program＇ of Chinese Academy of Sciences.
文摘The technique of optical tweezers has been improved a lot since its invention, which extends the application fields of optical tweezers. Besides the conventionally used Gaussian beams, different types of ring beams have also been used to form optical tweezers for different purposes. The two typical kinds of ring beams used in optical tweezers are the hollow Gaussian beam and Laguerre-Gaussian （LG） beam. Both theoretical computation and experiments have shown that the axial trapping force is improved for the ring beams compared with the Gaussian beam, and hence the trapping stability is improved, although the transverse trapping forces of ring beams are smaller than that of Gaussian beam. However, no systematic study on the trapping forces of ring beam has ever been discussed. In this article, we will investigate the axial and transverse trapping forces of different types of ring beams with different parameters systematically, by numerical computation in which the ray optics model is adopted. The spherical aberration caused by the refractive index mismatch between oil and water is also considered in the article. The trapping forces for different objectives that obey the sine condition and tangent condition are also compared with each other. The result of systematical calculation will be useful for the applications of optical tweezers formed by different types of ring beams.
基金Supported by Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2022L201)。
文摘AIM:To investigate the size of functional optical zone(FOZ)after small incision lenticule extraction(SMILE)versus femtosecond laser assisted excimer laser keratomileusis(FS-LASIK)for myopia correction and potential associated factors for FOZ.METHODS:A total of 133 patients who received corneal refractive surgery in our hospital between November 2018 and July 2021 were retrospectively enrolled.There were 63 patients(123 eyes)in SMILE group and 70patients(139 eyes)in FS-LASIK group.The size of FOZ was measured using Pentacam 3-dementional anterior segment analyzer before and 3mo after surgery,so as to analyze postoperative achieved functional optical zone(AFOZ)and its contributing parameters.RESULTS:When planned functional optical zone(PFOZ)was 6.5 mm for both groups,AFOZ was 1.45±0.27 and 1.67±0.25 mm smaller than preoperative FOZ in SMILE group and FS-LASIK group 3mo after surgery.AFOZ in SMILE group was significantly larger than that in FS-LASIK group(P<0.001).Variation of FOZ was negatively correlated with preoperative spherical equivalent(SE)and positively correlated with variation of mean keratometry value(△Km),variation of spherical aberration(△SA),and variation of Q-value(△Q,all P<0.001)in both groups.Multiple variable linear regression equations were△FOZ=1.354-0.1×pre-SE+0.336×△Q+1.462×△SA in SMILE group and△FOZ=1.512+0.137×△Q+0.468×△SA in FS-LASIK group.CONCLUSION:AFOZ is significantly smaller than preoperative FOZ in both SMILE and FS-LASIK groups.With the same PFOZ,larger AFOZ is achieved in SMILE group than in FS-LASIK group.
基金supported by the National Basic Research Program of China(Grant Nos.61205128,60908007,and 1102075)the Research Foundation for AdvancedTalents of Jiangsu University,China(Grant No.09JDG022)the Natural Science Foundation of Shanghai Municipal,China(Grant No.13ZR1414800)
文摘We conduct several experiments to further clarify the formation mechanism of a self-organized void array induced by a single laser beam, including energy-related experiments, refractive-index-contrast-related experiments, depth-related ex- periments, and effective-numerical-aperture experiment. These experiments indicate that the interface spherical aberration is indeed responsible for the formation of void arrays.
文摘The complex amplitude distribution which can compensate for the spherical aberration caused by mismatch on lnterthce between recording material and immersion material （air） on three-dimensional optical storage system is derived analytically and numerically. Comparison between two approaches is made. It is also shown how the depth of recording layer and position of reference plane are related to the phase distribution at reference plane and how the mismatch can be resolved by using a pure phase element.
基金supported by the National Natural Science Foundation of China(No.82301163)the Key Research and Development Program of Zhejiang Province(Award No.2024C03205).
文摘Purposes:To evaluate the impact of coronavirus disease 2019(COVID-19)on postoperative visual acuity,optical quality,and severity of dry eye disease in patients after small incision lenticule extraction(SMILE).Methods:This is a retrospective,comparative study.Patients who underwent SMILE were included and divided into two groups according to the period at the eye center of the Second Affiliated Hospital of Zhejiang University.The first group included patients who underwent SMILE before the large-scale COVID-19 pandemic in China(Group 1).The second group comprised patients who underwent SMILE during the pandemic with a confirmed infection of COVID-19(Group 2).The visual acuity,the severity of dry eye,ocular surface disease index(OSDI),oculus keratography analysis,and individual Zernike coefficients were evaluated and compared between the 2 groups.Results:A total of 43 eyes of 23 patients and 45 eyes of 26 patients were included in Groups 1 and 2,respectively.The OSDI score in Group 2 was significantly higher than Group 1(P<0.01).The corrected distance visual acuity(CDVA,logMAR)at 3 months postoperatively in Group 1 was better than in Group 2(P<0.001).Despite the improvement over 1 month after the COVID-19 infection,the OSDI score was still higher in Group 2 than in Group 1(P<0.01).The bulbar and limbal redness were significantly higher in Group 2 than in Group 1 at both 1 month and 3 months(P<0.05),while no significant differences were found in tear breakup time or tear meniscus height.Spherical aberration(SA)at the 4 mm zone was significantly higher in Group 2 than in Group 1 both at 1 month and 3 months(P<0.001),while no significant changes were observed in corneal total higher-order aberrations.No significant correlation was found between the bulbar/limbal redness index and SA.Conclusions:COVID-19 infection impaired visual outcomes and aggravated dry eye severity among postoperative SMILE patients.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20210227).
文摘In this Letter,we present a low-cost,high-resolution spectrometer design for ultra-high resolution optical coherence tomography(UHR-OCT),in which multiple standard achromatic lenses are combined to replace the expensive F-theta lens to achieve a comparable performance.For UHR-OCT,the spectrometer plays an important role in high-quality 3D image reconstruction.Typically,an F-theta lens is used in spectrometers as the Fourier lens to focus the dispersed light on the sensor array,and this F-theta lens is one of the most expensive components in spectrometers.The advantage of F-theta lens over the most widely used achromatic lens is that the aberrations(mainly spherical aberration,SA)are corrected,so the foci of the dispersed optical beams(at different wavelengths)with different incident angles could be placed on the sensor array simultaneously.For the achromatic lens,the foci of the center part of the spectrum are farther than those on the side in the longitudinal direction,causing degradations of the spectral resolution.Furthermore,in comparison with the achromatic lens with the same focal length,those with smaller diameters have stronger SA,but small lenses are what we need for making spectrometers compact and stable.In this work,we propose a simple method of using multiple long-focal-length achromatic lenses together to replace the F-theta lens,which is>8-fold cheaper based on the price of optical components from Thorlabs,US.Both simulations and in vivo experiments were implemented to demonstrate the performance of the proposed method.
文摘The electron gun with rotational surface cathode is presented to improve the laminarity of the converging electron beams in this paper,and the function expression of the rotational surfaces is given.The results of particle in cell(PIC)simulation indicate that anode-hole spherical aberration is the major cause for the nonlaminarity of the electron beams.By properly choosing the size of the shape,rotational surface cathode can effectively counteract the effect of the anode-hole spherical aberration and enhance the laminarity of the electron beams.The theoretical analysis was carried out for the explanation of the phenomenon that appeared in the PIC simulation.
