Advances in optical engineering for future telescopes

Significant optical engineering advances at the University of Arizona are being made for design, fabrication, and construction of next generation astronomical telescopes. This summary review paper focuses on the technological advances in three key areas. First is the optical fabrication technique used for constructing next-generation telescope mirrors. Advances in ground-based telescope control and instrumentation comprise the second area of development. This includes active alignment of the laser truss-based Large Binocular Telescope(LBT) prime focus camera, the new MOBIUS modular cross-dispersion spectroscopy unit used at the prime focal plane of the LBT, and topological pupil segment optimization. Lastly, future space telescope concepts and enabling technologies are discussed. Among these, the Nautilus space observatory requires challenging alignment of segmented multi-order diffractive elements. The OASIS terahertz space telescope presents unique challenges for characterizing the inflatable primary mirror, and the Hyperion space telescope pushes the limits of high spectral resolution, far-UV spectroscopy. The Coronagraphic Debris and Exoplanet Exploring Pioneer(CDEEP) is a Small Satellite(Small Sat) mission concept for high-contrast imaging of circumstellar disks and exoplanets using vector vortex coronagraph. These advances in optical engineering technologies will help mankind to probe, explore, and understand the scientific beauty of our universe.

Systematic Radio Telescope Alignment Using Portable Fringe Projection Profilometry

In 2019,the Event Horizon Telescope(EHT)released the first-ever image of a black hole event horizon.Astronomers are now aiming for higher angular resolutions of distant targets,like black holes,to understand more about the fundamental laws of gravity that govern our universe.To achieve this higher resolution and increased sensitivity,larger radio telescopes are needed to operate at higher frequencies and in larger quantities.Projects like the next-generation Very Large Array(ngVLA)and the Square-Kilometer Array(SKA)require building hundreds of telescopes with diameters greater than 10 ms over the next decade.This has a twofold effect.Radio telescope surfaces need to be more accurate to operate at higher frequencies,and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities.Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution.This leads to faster and more accurate panel alignment and,therefore,a more productive observatory.In this paper,we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish.The measurement takes only 10 min and directly delivers feedback on the tip,tilt,and piston of each panel to create the ideal reflector shape.

Review of bio-optical imaging systems with a high space-bandwidth product

Optical imaging has served as a primary method to collect information about biosystems across scales—from functionalities of tissues to morphological structures of cells and even at biomolecular levels.However,to adequately characterize a complex biosystem,an imaging system with a number of resolvable points,referred to as a space-bandwidth product(SBP),in excess of one billion is typically needed.Since a gigapixel-scale far exceeds the capacity of current optical imagers,compromises must be made to obtain either a low spatial resolution or a narrow field-of-view(FOV).The problem originates from constituent refractive optics—the larger the aperture,the more challenging the correction of lens aberrations.Therefore,it is impractical for a conventional optical imaging system to achieve an SBP over hundreds of millions.To address this unmet need,a variety of high-SBP imagers have emerged over the past decade,enabling an unprecedented resolution and FOV beyond the limit of conventional optics.We provide a comprehensive survey of high-SBP imaging techniques,exploring their underlying principles and applications in bioimaging.

On the Nature of Caspian Clouds

Caspian clouds(CCs)are formed between the southern coast of the Caspian Sea and the Alborz Mountains.The purpose of this study is to identify characteristics of CCs using aerosol,cloud,and meteorological data from ModernEra Retrospective analysis for Research and Applications version 2(MERRA-2),Moderate Resolution Imaging Spectroradiometer(MODIS),and ECMWF Reanalysis version 5(ERA5)during 2000–2020.During this period,we identified and investigated 636 days with CCs.The results indicated that the frequency(%)of these clouds was higher in the summer than in other seasons because synoptic system activity varies between hot and cold periods.The hot season with the beginning of high-pressure subtropical Azores activity and the formation of a stable atmosphere in northern Iran leads to more frequent occurrence of CCs.These clouds are mainly the low-and middle-level clouds in the region,e.g.,stratus and altocumulus.CCs resulted in 13.9%of annual rainfall,and 55.9%and 18.7%of the summer and autumn rainfall,respectively,relative to total rainfall from all cloud types in the study region.In the multivariate regression analysis,CC precipitation exhibited a strong positive relationship with the cloud water path(CWP),cloud optical thickness(COT),and cloud effective radius(CER).A comparison of the mean and standard deviation of aerosol optical thickness(AOT)and aerosol index(AI)for CC and non-CC days did not show a significant difference.Examination of the synoptic patterns showed that the main factors in the formation of CCs are the specific environmental conditions of the region and the orographic lift of stable air masses.The Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model indicated that the source of moisture for the formation of CCs was largely the Caspian Sea.

Assembly of multicomp on ent structures from hundreds of micron-scale building blocks using optical tweezers

The fabrication of three-dimensional(3D)microscale structures is critical for many applications,including strong and lightweight material development,medical device fabrication,microrobotics,and photonic applications.While 3D microfabrication has seen progress over the past decades,complex multicomponent integration with small or hierarchical feature sizes is still a challenge.In this study,an optical positioning and linking(OPAL)platform based on optical tweezers is used to precisely fabricate 3D microstructures from two types of micron-scale building blocks linked by biochemical interactions.A computer-controlled interface with rapid on-the-fly automated recalibration routines main tains accuracy eve n after placi ng many buildi ng blocks.OPAL achieves a 60-nm positional accuracy by optimizing the molecular functionalization and laser power.A two-component structure consisting of 4481-pm building blocks is assembled,representing the largest number of building blocks used to date in 3D optical tweezer microassembly.Although optical tweezers have previously been used for microfabrication,those results were generally restricted to single-material structures composed of a relatively small number of larger-sized building blocks,with little discussion of critical process parameters.It is anticipated that OPAL will enable the assembly,augmentation,and repair of microstructures composed of specialty micro/nanomaterial building blocks to be used in new photonic,microfluidic,and biomedical devices.

Ultra-high-Q free-space coupling to microtoroid resonators

Whispering gallery mode(WGM)microtoroid resonators are one of the most sensitive biochemical sensors in existence,capable of detecting single molecules.The main barrier for translating these devices out of the laboratory is that light is evanescently coupled into these devices though a tapered optical fiber.This hinders translation of these devices as the taper is fragile,suffers from mechanical vibration,and requires precise positioning.Here,we eliminate the need for an optical fiber by coupling light into and out from a toroid via free-space coupling and monitoring the scattered resonant light.A single long working distance objective lens combined with a digital micromirror device(DMD)was used for light injection,scattered light collection,and imaging.We obtain Q-factors as high as 1:6´108 with this approach.Electromagnetically induced transparency(EIT)-like and Fano resonances were observed in a single cavity due to indirect coupling in free space.This enables improved sensing sensitivity.The large effective coupling area(~10μm in diameter for numerical aperture=0.14)removes the need for precise positioning.Sensing performance was verified by combining the system with the frequency locked whispering evanescent resonator(FLOWER)approach to perform temperature sensing experiments.A thermal nonlinear optical effect was examined by tracking the resonance through FLOWER while adjusting the input power.We believe that this work will be a foundation for expanding the implementation of WGM microtoroid resonators to real-world applications.

Holography,and the future of 3D display

The pioneers of holography,Gabor,Leith,Upatnieks,and Denisyuk,predicted very early that the ultimate 3D display will be based on this technique.This conviction was rooted on the fact that holography is the only approach that can render all optical cues interpreted by the human visual system.Holographic 3D displays have been a dream chased after for many years,facing challenges on all fronts:computation,transmission,and rendering.With numbers such as 6.6×10^(15) flops required for calculations,3×10^(15) b/s data rates,and 1.6×10^(12) phase pixels,the task has been daunting.This article is reviewing the recent accomplishments made in the field of holographic 3D display.Specifically,the new developments in machine learning and neural network algorithms demonstrating that computer-generated holograms approach real-time processing.A section also discuss the problem of data transmission that can arguably be solved using clever compression algorithms and optical fiber transmission lines.Finally,we introduce the last obstacle to holographic 3D display,which is is the rendering hardware.However,there is no further mystery.With larger and faster spatial light modulators(SLMs),holographic projection systems are constantly improving.The pixel count on liquid crystal on silicon(LCoS)as well as microelectromechanical systems(MEMS)phase displays is increasing by the millions,and new photonic integrated circuit phased arrays are achieving real progress.It is only a matter of time for these systems to leave the laboratory and enter the consumer world.The future of 3D displays is holographic,and it is happening now.

Adaptive Thermoforming and Structural Design of Millimeter-Wave Antenna Panels

Future large-scale radio telescope observatories,such as the next-generation Very Large Array,involve extremely large collection areas.These collection areas are divided into smaller shaped panels,which typically require their own unique molds to manufacture.For these projects to be cost-effective,an efficient fabrication method for the shaped panels is needed.This paper outlines the development and success of a novel adaptive freeform panel molding technology that greatly improves manufacturing efficiency due to its repeatable and reusable nature.Moreover,it presents an analysis of a proposed panel structural design for the shaped panels,which incorporates a study on surface deformation due to gravity and wind loading under realistic operational conditions.

头戴式光场显示技术研究进展

光场显示器旨在通过重建三维场景在不同方向发出的几何光线来渲染三维场景的视觉感知,从而为人的视觉系统提供自然舒适的视觉体验,解决传统平面立体三维显示器中的聚散调节冲突问题。近年来,多种光场显示方法被尝试应用到头戴式显示技术中。本文对头戴式光场显示器的最新发展进行全面概述。

Towards a modular and scalable holographic display

Holographic three-dimensional(3D)display can be made very large using a modular system that allows seamless spatial tiling of multiple coarse integral holographic images.

Squeezed light goes flexible

Since its first experimental demonstration,squeezed light has been the driving force to push forward the frontier of quantum optics[1].Recently,with the rapid development of quantum information science,the study of squeezed light has entered a new stage,aiming at real-world impact beyond proof-of-principle demonstra-tions[2,3].One prominent example is Laser Interferom-eter Gravitational-wave Observatory(LIGO).

Self-consistent Maxwell–Bloch model for highorder harmonic generation in nanostructured semiconductors

In pursuit of efficient high-order harmonic conversion in semiconductor devices,modeling insights into the complex interplay among ultrafast microscopic electron–hole dynamics,nonlinear pulse propagation,and field confinement in nanostructured materials are urgently needed.Here,a self-consistent approach coupling semiconductor Bloch and Maxwell equations is applied to compute transmission and reflection high-order harmonic spectra for finite slab and sub-wavelength nanoparticle geometries.An increase in the generated high harmonics by several orders of magnitude is predicted for gallium arsenide nanoparticles with a size maximizing the magnetic dipole resonance.Serving as a conceptual and predictive tool for ultrafast spatiotemporal nonlinear optical responses of nanostructures with arbitrary geometry,our approach is anticipated to deliver new strategies for optimal harmonic manipulation in semiconductor metadevices.

Quantum receiver enhanced by adaptive learning

Quantum receivers aim to effectively navigate the vast quantum-state space to endow quantum information processing capabilities unmatched by classical receivers.To date,only a handful of quantum receivers have been constructed to tackle the problem of discriminating coherent states.Quantum receivers designed by analytical approaches,however,are incapable of effectively adapting to diverse environmental conditions,resulting in their quickly diminishing performance as the operational complexities increase.Here,we present a general architecture,dubbed the quantum receiver enhanced by adaptive learning,to adapt quantum receiver structures to diverse operational conditions.The adaptively learned quantum receiver is experimentally implemented in a hardware platform with record-high efficiency.Combining the architecture and the experimental advances,the error rate is reduced up to 40%over the standard quantum limit in two coherent-state encoding schemes.