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Simulating the detection and classification of high-redshift supernovae with HARMONI on the ELT
摘要： We present detailed simulations of integral ?eld spectroscopic observations of a supernova in a host galaxy at z ～ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, assisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova type from spectral features in the supernova spectrum. We ?nd that in a 3 h observation, covering the near-infrared H and K bands, at a spectral resolving power of ～3000, and using the 20 × 20 mas spaxel scale, we can classify Type Ia supernovae and their redshift robustly up to 80 d past maximum light (20 d in the supernova rest frame). We show that HARMONI will provide spectra at z ～ 3, which are of comparable (or better) quality to the best spectra we can currently obtain at z ～ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.
关键词： instrumentation: adaptive optics,instrumentation: spectrographs,galaxies: high-redshift,instrumentation: high angular resolution,supernovae: general
更新于2025-09-23 15:21:01
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Analysis of aberrations and performance evaluation of adaptive optics in two-photon light-sheet microscopy
摘要： Two-photon light-sheet microscopy (TP-LSM) system performance is greatly degraded by specimen-induced aberrations in illumination path, which limit the field of view, axial resolution and excitation efficiency of the system. Adaptive optics (AO) is an effective method for attenuating these effects. For the design and evaluation of an AO system, a comprehensive analysis of the effects of aberrations is needed. In this paper, a TP-LSM system is simulated, and new indexes based on integral intensity are introduced for the evaluation of an aberrated light-sheet. Then, the influences of each Zernike mode and random aberrations on the illumination path of the TP-LSM system are investigated with a numerical simulation method. Results show that high-order aberrations have little effect on the axial resolution and excitation efficiency of the system and only low-order components require correction. The random aberrations varied in strength with the depth of the specimens, so the number of corrected Zernike modes is variable. A general formula is generated for the estimation of the number of modes that should be detected and corrected under different aberrations and different numerical aperture of the objective. The results can provide important guidance in the design and evaluation of AO units for TP-LSM systems.
关键词： Two-photon Light-sheet Microscopy,Aberration correction,Adaptive optics
更新于2025-09-23 15:21:01
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Evaluating the Potential of Laser Beam Quality Improvement by Adaptive Optics System
摘要： AO (adaptive optics) systems have been extensively used to improve the beam quality in high-energy lasers; however, few studies have focused on how much the beam quality could be improved. A novel evaluation criteria and factor is presented in this paper. The factor, defined as power in ring (PIR), is expressed by distinguishing the low- and high-spatial frequency components in the far-field laser intensity distribution. Beams with different PIR values are generated in our model, and then they are compensated by AO systems. Calculation result shows that the PIR factor could evaluate a laser beam’s improvement potential by an AO system quantitatively.
关键词： high-energy lasers,power in ring,adaptive optics,beam quality,spatial frequency
更新于2025-09-23 15:19:57
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Photoreceptor assessment in focal laser-treated central serous chorioretinopathy using adaptive optics and fundus autofluorescence
摘要： This study analyzed cone density, cone mosaic, and fundus autofluorescence (FAF) images in patients with focal laser-treated central serous chorioretinopathy (CSC). Observational case series. Forty-two eyes of 21 patients with unilateral treated CSC and bilateral best-corrected visual acuity of 1.0 (decimal fraction) were included. FAF and cone mosaic images were obtained in all patients with an adaptive optics fundus camera. Densities were recorded at 20 points throughout the macula, and choroidal thicknesses were measured. Mean choroidal thicknesses were 419.95 ± 110.33 mm in normal eyes, 459.09 ± 90.07 mm in eyes with active CSC, and 438.61 ± 107.57 mm in treated eyes. The highest density of cones in healthy eyes was 38146 cones/mm2, with a 5.66-mm intercellular space (IS), at 700 mm temporal to the center. In eyes with treated CSC, the highest density was 32749 cones/mm2, with a 6.13-mm IS, at 500 mm nasal to the center. In all quadrants, median values of maximum cone density were significantly higher in healthy eyes (P = .02, P = .003, P = .0001, and P = .001). Three types of lesions were identified on FAF and were correlated with those on cone mosaic images. Strong correlations were detected between the presence of hypoautofluorescent lesions on the first FAF image and a greater difference between maximum values of photoreceptor density (r2 = 0.46, P = .03), as well as between the presence of hypoautofluorescent lesions and the duration of pathology (r2 = 0.68, P < .001). The presence of hypoautofluorescent lesions and the duration of pathology were negative prognostic factors in CSC. Laser treatment could prevent photoreceptor loss.
关键词： photoreceptor density,cone mosaic,fundus autofluorescence,laser-treated central serous chorioretinopathy,adaptive optics
更新于2025-09-23 15:19:57
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Efficient injection from large telescopes into single-mode fibres: Enabling the era of ultra-precision astronomy
摘要： Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J ? H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86% of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30% in the range 1250–1600 nm. Preliminary on-sky data with a Strehl ratio of 60% in the H-band produced a coupling efficiency into a single-mode fibre of ～50%, consistent with expectations. The coupling was >40% for 84% of the time and >50% for 41% of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90% in H-band) would allow coupling of >67% (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20% in H-band) would allow coupling of >18%. For Strehl ratios <20%, few-port photonic lanterns become a superior choice but the signal-to-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.
关键词： instrumentation: interferometers,instrumentation: high angular resolution,instrumentation: spectrographs,instrumentation: adaptive optics
更新于2025-09-19 17:15:36
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Multimodal imaging of torpedo maculopathy including adaptive optics
摘要： Purpose: The etiology of torpedo maculopathy remains unknown, but it has been recently suggested that it could represent a persistent defect in the development of the retinal pigment epithelium. As retinal pigment epithelium and photoreceptors form a functional unit, an alteration of photoreceptor distribution or function is predictable. The aim of this study is to describe multimodal imaging, including adaptive optics, in three cases of torpedo maculopathy, and discuss its pathogenesis. Methods: Multimodal imaging is presented, including fundus photographs, optical coherence tomography, adaptive optics, autofluorescence, fluorescein angiography, and ultra-widefield retinal imaging in three cases of torpedo maculopathy. Results: An oval-shaped well-delimited chorioretinal lesion both hypopigmented centrally and with a hyperpigmented border in the temporal macula, consistent with torpedo maculopathy, was observed in three patients. Optical coherence tomography showed a preservation of the inner retina, a mild atrophy of the outer retina, an alteration of the ellipsoid zone and of the retinal pigment epithelium layer, and a neurosensory detachment. These lesions were hypoautofluorescent with a hyperautofluorescent border. Fluorescein angiography showed a hyperfluorescence by window effect. Adaptive optics imaging showed an alteration of the cone mosaic within the lesions, with a lower cone density and a higher spacing between cones. Conclusion: The alteration of the cone mosaic suggested by adaptive optics in torpedo maculopathy has never been described and could be explained by the alteration of the retinal pigment epithelium. Our results support the existing hypothesis on the pathogenesis of torpedo maculopathy that a persistent defect in the development of the retinal pigment epithelium may be responsible for this clinical entity.
关键词： retinal imaging,Torpedo maculopathy,multimodal imaging,adaptive optics
更新于2025-09-19 17:15:36
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Over compensation algorithm for laser beam shaping using a deformable freeform mirror
摘要： We propose an over compensation (OC) algorithm for laser beam shaping using deformable mirrors. In this algorithm, we model the beam shaping problem using a sequence of standard Monge-Ampère (MA) equations and iteratively applies over compensation to the deviated focal-plane irradiance distributions. Simulations show that this algorithm can get its minimum relative root mean square deviations (RRMSDs) using only a few iterations and actuator perturbations.
关键词： Freeform optics,Active or adaptive optics,Laser beam shaping
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Experimental demonstration of atmospheric channel reciprocity in fiber receiving systems
摘要： This paper designs a reciprocity measurement system for atmospheric channel for the first time in China. The mean of reciprocity is higher than 0.8, which proves that the atmospheric channel has strong reciprocity. The research in this paper provides a parameter reference for adaptive optics system design.
关键词： Atmospheric turbulence,Optical Communication,Adaptive optics
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22–26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Adaptive optics for intra-volume engraving of glass with ultra-short laser pulses
摘要： Within the frame of high precision ultrafast laser processing of transparent materials, we report here on the use of adaptive optics as a tool for intra-volume laser engraving of glass. With the active monitoring of the laser beam wavefront, the repartition of the above-threshold energy in the focal volume is actively detected. Therefore, the elongation of the laser-induced modification due to longitudinal spherical aberration can be minimized or emphasized on demand. Indeed, the industrial adaptive optics set up, made of a wavefront sensor and a deformable mirror, permits the management of each wavefront aberration as RMS values of chosen Zernike polynomials coefficients. This technique allows the control of the processing of transparent dielectrics, whatever the index of refraction and the depth are. This study addresses the precise correlation between wavefront distortions and intra-volume modifications in borosilicate glass obtained with a 300 fs Yb-doped fiber laser running at 1030 nm. The effects of the 3rd and 5th orders of longitudinal spherical aberrations on the laser-induced marking of the bulk are investigated with the purpose of precisely controlling the length of the interaction volume in the illuminated dielectric material. We show here a minimization of the total length of the marking by 65% at 600 μm in depth, from the natural wavefront to the optimized one, close to the diffraction limit.
关键词： wavefront distortions,ultra-short laser pulses,intra-volume engraving,adaptive optics,glass,longitudinal spherical aberrations
更新于2025-09-16 10:30:52
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On compensating thermal lensing in high-power lasers using intra-cavity deformable mirrors
摘要： Thermal lensing limits the beam quality of high-power lasers and evokes setpoint-dependent disturbances. Since these effects cannot be corrected outside the resonator, intra-cavity deformable mirrors stand to reason. Based on a Gaussian cavity and a disturbance model with distributed parameters, we derive a discrete-time estimation scheme. Due to the nonlinearities of the optical system, estimating and predicting the disturbance is crucial in order to construct a proper compensation. The presented recursive optimization-based approach considers input constraints in an explicit manner. Finally, the performance of the proposed disturbance rejection is demonstrated by simulations. The algorithm reduces the feedback control effort by more than 90% and improves the tracking behavior of the closed loop.
关键词： mechatronics,high-power lasers,disturbance estimation,adaptive optics
更新于2025-09-16 10:30:52