Observation of the early blood vessels of cutaneous malignant melanoma using Swept Source Optical Coherence Tomography A ngiography(SS-OCTA)

Melanoma,characterized by high mortality,rapid development and accompanied with angio-genesis is the most typical malignant tumor in skin cancer.Hence,the detection of blood vessels is of much significanoe.The early vascular network has small scale.If we remove the tumor early and biopsy it,it will increase the spread of the cancer cells and infection and bleeding.In this case,we presented a new angiography method.A high-resolution OCT system for noninvasive an-giographic imaging of early skin melanoma-Swept Source Optical Coberence Tomography Angiography(SS-OCTA)is proposed.With a high lateral resolution of 10pm in vrivo tomographic angiography,SS-OCTA is used to image and identify the morphology of the early tumor blood vessels.In addition,a control group experiment is conducted to observe the growth of melanoma in the process of rupture,malormation of micro-vessels.The results of the analysis and statistical test(P<0.05)are statistically signifcant.

Macular Bruch's membrane defects and other myopic lesions in high myopia

AIM: To compare the ocular fundus features of highly myopic eyes with and without macular Bruch’s membrane(BM) defects and investigate the associations between macular BM defects and other myopic lesions.METHODS: This retrospective, observational case series included 262 eyes(139 patients) with high myopia(HM) refractive error ≥-6.0 diopters(D) or axial length ≥26.5 mm from March 2019 to December 2019.The patients underwent a comprehensive ophthalmic examination, including sweptsource optical coherence tomography(SS-OCT).The features of macular BM defects and other ocular fundus lesions were examined in OCT images.RESULTS: Totally 51 eyes(19.5%) were detected with macular BM defects, which were characterized by a lack of BM, retinal pigment epithelium(RPE), and an almost complete loss of photoreceptors or choriocapillaris.Eyes with macular BM defects had worse best-corrected visual acuity(BCVA) than those without(P<0.001).Dome-shaped macula(DSM, P=0.042), retinal cysts(P=0.006), choroidal neovascularization(CNV, P<0.001), choroidal defects and abnormality(P=0.003), scleral defects(P=0.015), scleral deformation(P=0.005), posterior staphyloma(P=0.011), and perforating vessels(P<0.001) occurred more frequently in eyes with macular BM defects.In multivariate analysis, the presence of macular BM defects remained the significant association with presence of DSM(P=0.013), scleral defects(P=0.015), posterior staphyloma(P=0.001), perforating vessels(P<0.001) and CNV(P=0.004).CONCLUSION: Macular BM defects has a prevalence of approximately 20% in HM and it has tight association with other myopic fundus lesions.BM might be crucial in the pathogenesis of myopic fundus lesions due to its biomechanical function.A comprehensive understanding of BM’s role is useful for further researches about myopic lesions.

An orientation method and analysis of optical radiation sources based on polyhedron and parallel incident light

The spatial orientation of optical radiation sources has long been the hot topic in the aerospace and the military applications.Current researches mainly focus on the high precision orientation on the partial field of view.Thus,combination of several partial fields of view is required to achieve orientation when the field of view exceeds 180°,which results in the increase of size,weight,power consumption and the cost.By defining radiation energy and direction of the optical radiation source as a vector and applying the cosine law of radiation and vector theorem,it is shown that the vector can be obtained from unit normal vectors on the three un-coplanar surfaces and from the energy projected by the optical radiation source.Based on this,an orientation method with 360° full field of view by a polyhedron is suggested,the mathematical formula for anti-multipath interference is supposed and the error upper limit is derived.The feasibility and effectiveness of this method are validated by measurements and simulation.An accuracy better than 2.866° and 0.574° is achieved when the ratio of measurement error of energy on arbitrary surface and the true value are 5% and 1%,respectively,given the matrix composed of unit normal vectors on three measurement surfaces is orthogonal.

Anterior and posterior segment structural features of acute primary angle-closure eyes:date based on AS-OCT and SS-OCT

Background:To measure the anterior and posterior segment structural features of acute primary angle-closure(APAC)eyes.Methods:A total of 36 subjects with unilateral APAC were recruited in this study.The ocular biometric characteristics were measured by anterior segment optical coherence tomography(AS-OCT)and swept source optical coherence tomography(SS-OCT),respectively at baseline,2 weeks,and 1 month after surgical intervention.Results:At baseline,when compared with the fellow eyes,APAC-affected eyes showed significantly greater corneal thickness(P=0.004),shallower anterior chamber depth(ACD)(P<0.001),smaller anterior chamber area(ACA)(P=0.013),angle opening distance at 750μm from the scleral spur(AOD750)(P=0.002),trabecular-iris space area at 750μm from the scleral spur(TISA750)(P=0.033),angle recess area(ARA)(P=0.014),and iris area(IARE)(P=0.003),less iris curvature(ICURVE)(P=0.003),and larger lens vault(LV)(P=0.030).After intervention,the corneal thickness was significantly decreased at 1 month(P<0.001),while ACD,ACA,and AOD750 were significantly increased at 2 weeks and 1 month(all P<0.017).Changes in ACD were correlated with decreasing LV(P<0.05).The posterior segment parameters did not change over the 4-week period.Conclusions:When compared with the fellow eyes,APAC-affected eyes had greater corneal thickness,shallower anterior chamber,narrower angle,less ICURVE,and larger LV.After intervention,the corneal thickness was decreased,while the shallower anterior chamber was relieved to some extent.

Understanding hydrogen plasma processes based on the diagnostic results of 2.45 GHz ECRIS at Peking University

Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.

Frequency and wavelength tunable optical microwave source based on a distributed Bragg reflector self-pulsation laser

A frequency and wavelength tunable self-pulsation laser based on DBR laser devices is reported for the first time.This laser generates continuous tunable optical microwave in the range of 1.87-21.81 GHz with 3-dB linewidth about 10 MHz by tuning the injection currents on the front and back gain sections,and exhibits wavelength tuning range from 1536.28 to 1538.73 nm by tuning the injection currents on the grating section.

Photonic microwave true time delays for phased array antennas using a 49 GHz FSR integrated optical micro-comb source[Invited]

We demonstrate significantly improved performance of a microwave true time delay line based on an integrated optical frequency comb source. The broadband micro-comb(over 100 nm wide) features a record low free spectral range(FSR) of 49 GHz, resulting in an unprecedented record high channel number(81 over the C band)—the highest number of channels for an integrated comb source used for microwave signal processing. We theoretically analyze the performance of a phased array antenna and show that this large channel count results in a high angular resolution and wide beam-steering tunable range. This demonstrates the feasibility of our approach as a competitive solution toward implementing integrated photonic true time delays in radar and communications systems.

Effect of orthokeratology on precision and agreement assessment of a new sweptsource optical coherence tomography biometer

Background:To evaluate the effect of orthokeratology on precision of measurements in children using a new swept-source optical coherence tomography(SS-OCT)optical biometer(OA-2000),and agreement between its measurements and those provided by the commonly used IOLMaster based on partial coherence interferometry(PCI).Methods:This study recruited fifty-one eyes of 51 normal children(8–16 years).An operator took measurements with the two biometers.Then,a second operator took measurements with the SS-OCT biometer.After orthokeratology was performed for one month,the same operators repeated the same procedures.Axial length(AL),mean keratometry(Km)at 2.5 mm and 3.0 mm diameters(Km2.5 and Km3.0),central corneal thickness(CCT),anterior chamber depth(ACD),lens thickness(LT)and corneal diameter(CD)were analyzed.Results:With the SS-OCT optical biometer,the test-retest repeatability of AL measurements was<0.06 mm.For all parameters,the coefficients of variation were<1.23%and the intraclass correlation coefficients were>0.95.The 95%limits of agreement of difference between the two devices for CD parameter were up to 1.53 mm.After orthokeratology,the fluctuation ranges of difference for Km3.0 measurement was 1.11 times higher than before orthokeratology,while the absolute values of difference for AL,Km2.5,ACD and CD measurements were comparable.Conclusions:Before and after orthokeratology,the SS-OCT biometer showed high repeatability and reproducibility for all measurements.Wearing orthokeratology contact lenses affected the agreement between SS-OCT and PCI biometers for Km3.0 measurements.The CD measurement showed poor agreement between the two devices.

Plasma parameter diagnosis using hydrogen emission spectra of a quartz-chamber 2.45 GHz ECRIS at Peking University

A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydrogen ion beam at 50 k V with a duty factor of 10%. The root-mean-square(RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work,the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10^(-4) to 1×10^(-3) Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.