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Solid-state single-photon emitters (SPEs) commonly encounter the limitation of quasi-omnidirectional radiation patterns, which poses challenges in utilizing their emission with conventional optical instruments. In this study, we demonstrate the tailoring of the far-field radiation patterns of SPEs based on colloidal quantum dots (QDs), both theoretically and experimentally, by employing a polymer-based dielectric antenna. We introduce a simple and cost-effective technique, namely low one-photon absorption direct laser writing, to achieve precise coupling of a QD into an all-polymer circular waveguide resonance grating. By optimizing the geometry parameters of the structure using 3D finite-difference time-domain simulations, resonance at the emission wavelength of QDs is achieved in the direction perpendicular to the substrate, resulting in photon streams with remarkably high directivity on both sides of the grating. Theoretical calculations predict beam divergence values below 2°, while experimental measurements using back focal plane imaging yield divergence angles of approximately 8°. Our study contributes to the evaluation of concentric circular grating structures employing low refractive index polymer materials, thereby expanding the possibilities for their application. [ABSTRACT FROM AUTHOR]

Photonic lanterns (PLs) are tapered waveguides that gradually transition from a multimode fiber geometry to a bundle of single-mode fibers (SMFs). They can efficiently couple multimode telescope light into a multimode fiber entrance at the focal plane and convert it into multiple single-mode beams. Thus, each SMF samples its unique mode (lantern principal mode) of the telescope light in the pupil, analogous to subapertures in aperture masking interferometry (AMI). Coherent imaging with PLs can be enabled by the interference of SMF outputs and applying phase modulation, which can be achieved using a photonic chip beam combiner at the backend (e.g., the ABCD beam combiner). In this study, we investigate the potential of coherent imaging by the interference of SMF outputs of a PL with a single telescope. We demonstrate that the visibilities that can be measured from a PL are mutual intensities incident on the pupil weighted by the cross correlation of a pair of lantern modes. From numerically simulated lantern principal modes of a 6-port PL, we find that interferometric observables using a PL behave similarly to separated-aperture visibilities for simple models on small angular scales (< λ / D) but with greater sensitivity to symmetries and capability to break phase angle degeneracies. Furthermore, we present simulated observations with wave front errors (WFEs) and compare them to AMI. Despite the redundancy caused by extended lantern principal modes, spatial filtering offers stability to WFEs. Our simulated observations suggest that PLs may offer significant benefits in the photon-noise-limited regime and in resolving small angular scales at the low-contrast regime. [ABSTRACT FROM AUTHOR]

This paper presents an enhanced chromatic dispersion probe for simultaneous measurement of dual-axis absolute and relative displacement with nanometric resolutions based on a 4 f optical system and a signal processing algorithm. In the 4 f optical system, a light source is generated by a pinhole in such a way that the employed pinhole is placed on the focal planes of the two achromatic lenses, aimed at generating a low-pass filter in the frequency domain. With a smaller pinhole, side lobes of the measured spectra are effectively suppressed and the signal-to-noise ratio is optimized, resulting in an expanded absolute measurement range and improved resolution of the two axes, and an enhanced relative measurement resolution of the dual-axis. A signal processing algorithm is proposed in such a way that in the spectral curvature region of the dual-axis output spectra, the original fitted spectrum is replaced by a linear fitting line and a newly-intersected wavelength can be obtained, resulting in an expanded measurement range of the relative displacement of the dual-axis. Numerical simulation and experiments have indicated that the absolute measurement range has been expanded to 225 μm with an enhanced resolution of 40 nm, and the measurement range of the relative displacement of the dual-axis has been expanded to 370 μm with an enhanced relative measurement resolution of 90 nm. [ABSTRACT FROM AUTHOR]

The precondition for the application of light beams is the ability to devise light distribution with high precision. Controlling more dimensions for structured light fields is an effective method to improve the ability to devise light distribution. The Swallowtail beam, due to its rich regulatory parameters, provides the possibility to design a light field with a specific intensity distribution. Utilizing the Swallowtail beam as a foundation, we design its initial phase, polarization, and coherent structure, and propose a partially coherent azimuthally polarized circular vortex Swallowtail Gaussian beam (PCAPCVSGB) in our paper. This beam exhibits an abnormal self-focusing ability and forms an easily adjustable optical potential well at the focal plane, providing another effective tool for achieving optical manipulation. In addition, the PCAPCVSGB also shows an interesting vector property. It possesses a stable polarization singularity even with changes in coherence and topological charges, which exhibits a potential application value in optical communication. [ABSTRACT FROM AUTHOR]

We study the propagation of non-isotropically correlated vector vortex beams (NCVVBs) through an ABCD optical system. The statistical properties, namely, intensity, state of polarization, degree of polarization (DoP), and degree of coherence (DoC) of these beams are investigated. The terminology non-isotropically correlated is used for electromagnetic Gaussian Schell-model beams, that exhibit the distinguishability of spatial correlations between parallel and orthogonal electric field components. The non-isotropic feature of the correlation widths introduces an azimuthal asymmetry in the intensity, DoP, and DoC distributions. The azimuthal asymmetry in the intensity and DoC distributions become prominent around the focal plane. However, this asymmetry can be clearly observed in DoP distributions even at a very short propagation distance. It is found that the statistical properties of NCVVBs are dependent on both Poincaré–Hopf index (PHI) and the source correlation parameters. The number of beamlets in the intensity distribution is twice the magnitude of the PHI of the input beam. Unlike isotropically correlated vector vortex beams, correlation-induced polarization around the central core of the NCVVB is observed. The DoC distribution exhibits the evolution of correlation singularities in the form of dislocations at the far field plane. These dislocations in the DoC profile under lower correlations depend on the PHI, which provides a feasible approach to measure the index of NCVVBs. This study provides a technique to synthesize beams with structured correlation and polarization features. [ABSTRACT FROM AUTHOR]

The transmission of light through sub-wavelength apertures (zero-mode waveguides, ZMW) in metal films is well-explored. It introduces both an amplitude modulation as well as a phase shift to the oscillating electromagnetic field. We propose a nanophotonic interferometer by bringing two ZMW (∼100 nm diameter) in proximity and monitoring the distribution of transmitted light in the back-focal plane of collecting microscope objective (1.3 N.A.). We demonstrate that both an asymmetry induced by the binding of a quantum dot in one of the two ZMW, as well as an asymmetry in ZMW diameter yield qualitatively similar transmission patterns. We find that the complex pattern can be quantified through a scalar measure of asymmetry along the symmetry axis of the aperture pair. In a combined experimental and computational exploration of detectors with differing ZMW diameters, we find that the scalar asymmetry is a monotonous function of the diameter difference of the two apertures, and that the scalar asymmetry measure is higher if the sample is slightly displaced from the focal plane of the collecting microscope objective. An optimization of the detector geometry determined that the maximum response is achieved at an aperture separation that is comparable to the wavelength on the exit side of the sensor. For small separations of apertures, on the order of a quarter of the wavelength and less, the signal is strongly polarization dependent, while for larger separations, on the order of the wavelength or larger, the signal becomes essentially polarization-independent. [ABSTRACT FROM AUTHOR]

The Near-Infrared Spectrograph (NIRSpec) is one of the four focal plane instruments on the James Webb Space Telescope. In this paper, we summarize the in-orbit performance of NIRSpec, as derived from data collected during its commissioning campaign and the first few months of nominal science operations. More specifically, we discuss the performance of some critical hardware components such as the two NIRSpec Hawaii-2RG detectors, wheel mechanisms, and the microshutter array. We also summarize the accuracy of the two target acquisition procedures used to accurately place science targets into the slit apertures, discuss the current status of the spectrophotometric and wavelength calibration of NIRSpec spectra, and provide the "as measured" sensitivity in all NIRSpec science modes. Finally, we point out a few important considerations for the preparation of NIRSpec science programs. [ABSTRACT FROM AUTHOR]

We propose an optical setup based on a spatial light modulator (SLM) to facilitate rapid micro structuring such as laser lithography. The beam shaping of the system was addressed and we were able to minimize the effect of common issues of SLMs by adjusting our optical setup. We separated the zero-order focal plane from the first image plane via a focus shift to improve the image quality. This causes a Fourier filtering which is theoretically analyzed. This work explains challenges in filtering the zero-order beam and validates the achievable resolution of ∼11 μ m of the proposed setup. The speed of maskless structuring can be improved by this approach while maintaining the resolution. We demonstrated the use of the setup for SLM-based maskless laser lithography. [ABSTRACT FROM AUTHOR]

We propose an optical setup based on a spatial light modulator (SLM) to facilitate rapid micro structuring such as laser lithography. The beam shaping of the system was addressed and we were able to minimize the effect of common issues of SLMs by adjusting our optical setup. We separated the zero-order focal plane from the first image plane via a focus shift to improve the image quality. This causes a Fourier filtering which is theoretically analyzed. This work explains challenges in filtering the zero-order beam and validates the achievable resolution of ∼11 μ m of the proposed setup. The speed of maskless structuring can be improved by this approach while maintaining the resolution. We demonstrated the use of the setup for SLM-based maskless laser lithography. [ABSTRACT FROM AUTHOR]

Based on the phase-change material Ge2Sb2Te5 (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems. [ABSTRACT FROM AUTHOR]

Based on the phase-change material Ge2Sb2Te5 (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems. [ABSTRACT FROM AUTHOR]

Line intensity mapping (LIM) is a new technique for tracing the global properties of galaxies over cosmic time. Detection of the very faint signals from redshifted carbon monoxide (CO), a tracer of star formation, pushes the limits of what is feasible with a total-power instrument. The CO Mapping Project Pathfinder is a first-generation instrument aiming to prove the concept and develop the technology for future experiments, as well as delivering early science products. With 19 receiver channels in a hexagonal focal plane arrangement on a 10.4 m antenna and an instantaneous 26â€"34 GHz frequency range with 2 MHz resolution, it is ideally suited to measuring CO (J = 1â€"0) from z ∼ 3. In this paper we discuss strategies for designing and building the Pathfinder and the challenges that were encountered. The design of the instrument prioritized LIM requirements over those of ancillary science. After a couple of years of operation, the instrument is well understood, and the first year of data is already yielding useful science results. Experience with this Pathfinder will guide the design of the next generations of experiments. [ABSTRACT FROM AUTHOR]

Hybrid optical elements, which combine refractive and diffractive optical components to enhance optical performance by taking advantage of the optical characteristics of the individual components, have enormous potential for next-generation optical devices. However, there have not been many reports on the simulation methodology to characterize such hybrid optical systems. Here, we present a method for simulating a hybrid optical element realized by attaching an ultra-thin, flexible diffractive optics array onto a refractive optical element. The ultra-thin diffractive optical element is fabricated by direct-laser-writing using a femtosecond pulsed laser as the light source. A systematic investigation of the proposed simulation method, which does not require extensive hardware resources or computational time, but retains resolution and accuracy, is presented. The proposed scheme is validated by comparing simulation and experimental results. The simulation and experimental results on the spot size and focal length for the diffractive Fresnel zone plate (FZP) match well, with typical errors of less than 6%. The aspect ratio of the focal spot sizes at the compound and FZP focal planes of the hybrid optical system from the simulation and experiment also match quite well, with typical errors below 7%. This simulation scheme will expedite the designs for novel hybrid optical systems with optimal optical performances for specific applications, such as microfluidics and aberration-controlled optics. [ABSTRACT FROM AUTHOR]

Accurate detection and analysis of the cathode surface temperature delivers an important reference value as regards the prediction of electrode life and corrosion degree, a thorough study of the vacuum-breakdown phenomenon, design and application of the vacuum-arc ion source and vacuum switch. In this paper, multispectral true temperature measurement T of the surface temperature field of pulsed vacuum arc cathode materials under different discharge currents is carried out. Firstly, aiming at solving the problem of synchronous imaging measurement of the temperature field across the cathode of pulsed vacuum arc, a multi-wavelength monochromatic image-acquisition optical path is designed, based upon the image acquisition module of a high-speed monochrome camera. Also, multiple monochromatic spectral radiation images of the target are synchronously acquired on the focal plane of the same monochrome camera detector. As a result, the spectral-radiation image information of multiple wavelengths can be obtained in a single exposure time, which greatly shortens the temperature-field image acquisition time. Secondly, based upon the multispectral true-temperature calculation method, high-speed multispectral imaging measurement of the target temperature field is realized. Finally, the two-dimensional true temperature distribution of the cathode temperature field under different current conditions was studied by setting up an experimental platform for measuring the cathode temperature of the vacuum arc under different current conditions. [ABSTRACT FROM AUTHOR]

Vector vortex beams play an important role in tailoring tightly focused fields by creating an additional longitudinal component at the focal plane. Until now, mainly focusing properties of fundamental, higher order vector fields and negative indexed ellipse fields have been investigated. In this paper we numerically analyze tight focusing behaviour of ellipse fields embedding C-point singularities of index I C = ± 1 2 , I C = ± 1 , I C = ± 3 2 and I C = ± 2. We show that both the sign and absolute value of C-point index (I C ) of the ellipse fields play an important role in tailoring the focal intensity landscapes. For negative index C-points the intensity distribution of the longitudinal components show symmetries that correspond to the number of separatrices present in the polarization distribution. At the focal plane, both transverse and longitudinal components of the ellipse fields are found to be embedded with phase singularities. These ellipse fields can be useful in advanced microscopy for shaping the focus of light fields for various applications. [ABSTRACT FROM AUTHOR]

The use of propagation-invariant Airy beams enables a light-sheet microscopy with a large field-of-view. Without relying upon two-photon excitation or deconvolution-based processing to eliminate out-of focus blur caused by the side lobes, here, we present how the subtraction method is applied to enhance the image quality in digital scanned light-sheet microscopy with Airy beam. In the proposed method, planar Airy beam with the symmetric transversal structure is used to excite the sample. A hollow Airy beam with zero intensity at the focal plane is created, which is mainly used to excite the out-of-focus signal. By scanning the sample twice with the normal planar Airy beam and the hollow Airy beam, digital post-processing of the obtained images by subtraction allows for the rejection of out-of-focus blur and improves the optical sectioning, the axial resolution and the intensity distribution uniformity of the light-sheet microscopy. [ABSTRACT FROM AUTHOR]

A weakly focused light beam is studied numerically in the focal plane, to observe the linear polarization separation and circular polarization accumulation in the beam cross section. This is an example of spin-orbit interaction of light, where the extrinsic orbital angular momentum of light encountered due to focusing is converted into spin angular momentum and causes circular polarization generation and linear polarization separation in different parts of the beam cross section. This effect is studied by evaluating the polarization vector and Stokes vector and angle parameters in the beam cross section in detail. Because of the lens’s spherical geometry and origination of geometric phase, the accumulation of the spin component in the beam cross section is observed to be circularly symmetric, while the linear polarization shows splitting into orthogonal polarization components in the beam cross section. The underlying results may have an important role for understanding the spin-orbit interaction in a weakly focused system at a fundamental level and can be useful in many applications of nanophotonics. [ABSTRACT FROM AUTHOR]

Maskless lithography is an increasingly popular method of micro-patterning in research settings. This technical note presents methods for controlling the feature size and sidewall profile of thick-resist features, when exposed using maskless direct imaging systems. Maskless lithographic systems use focussed, uncollimated light, and therefore do not naturally produce the vertical sidewalls that may be required for soft lithography and other secondary processes. We explore exposure dose energy, placement of the focal plane, and the use of multiple focal planes to optimize features in thick (∼800 μm) SU-8 resist. We find that placing the image plane at the mid-height of the resist film produces structures with a good compromise of sidewall angle and feature sharpness. We also find that using multiple exposures at multiple heights can produce sidewall angles that are stable over a range of dose energies. [ABSTRACT FROM AUTHOR]

An instrument is demonstrated that is capable of simultaneous and independent flow density fluctuation measurements over the same line-of-sight by combining two optical techniques: focused laser differential interferometry (FLDI) and high-speed schlieren (HSS). The FLDI instrument measures fluctuations at a single point in the flowfield at 10 MHz, with the resulting signal most sensitive in the region nearest the focal plane of the FLDI laser beam. The HSS instrument acquires images at 20 kHz along the same optical axis as the FLDI beam, but with the resulting signal path averaged over the entire HSS line-of-sight. The introduction of the HSS optics into the FLDI beam path provides two high-quality measurement capabilities in a single system with no degradation of performance relative to stand-alone FLDI or HSS instruments. [ABSTRACT FROM AUTHOR]

An approach for yielding light focuses below Abbe's diffraction limit in Gaussian beams is presented. The method uses only standard passive optical elements as lenses, filters and mirrors and consists of a Michelson interferometric setup, where one of the light branches is modified in amplitude and/or phase. The focus narrowing process is carried out at the focal plane of a spherical lens by the interference of altered and unaltered light branches. The main focus features, namely, the focus intensity and size as well as the sidelobe intensity, are adjusted by varying two external parameters in a controllable manner under the conditions of pure destructive interference. Narrowing of the diffraction limit close to 40% with reduced intensity sidelobes (10%) is achieved. Due to the use of only lenses and mirrors, the approach does work with laser beams within a broad optical bandwidth ranging from infrared to ultraviolet in continuum regime as well as in ultra-short pulse regime. The method can also be implemented for high-power lasers and temporal domains. The focus-narrowing process emerges as a natural mechanism to the light interference, bringing a fresh perspective to applications from a few controllable degrees of freedom. The good performance of the sub-diffraction optical focus and the simplicity of the experimental setup promote new opportunities in fields ranging from optical manipulation of particles at sub-wavelength scale to optical writing and super-resolution microscopy. [ABSTRACT FROM AUTHOR]

A new phase retrieval method is investigated to reconstruct wavefronts of optical parallel plates with the use of a group of diffraction patterns. More specifically, the improved phase retrieval algorithm is realized by converting the measuring plane wave into a spherical wave and by using single or double discrete Fourier transforms to calculate both far- and near-field diffraction propagations, and the accuracy is improved by adjusting the exposure time of the charge-coupled device according to the distance between the focal plane and diffraction plane. Both the theoretical and experimental results are consistent with the results obtained using conventional wavelength-modulated phase-shifting interferometry. The new method opens new doors for realizing wavefront measurement of optical parallel plates with high accuracy, especially for large-aperture parallel plates in inertial confinement fusion laser systems. [ABSTRACT FROM AUTHOR]

We demonstrate a passive down-conversion imaging system that converts broadband ultraviolet light to narrow-band green light while preserving the directionality of rays, and thus enabling direct down-conversion imaging. At the same time our system has high transparency in the visible, enabling superimposed visible and ultraviolet imaging. The frequency conversion is performed by a subwavelength-thickness transparent downconverter based on highly efficient CsPbBr3 nanocrystals incorporated into the focal plane of a simple telescope or relay-lens geometry. The resulting imaging performance of this down-conversion system approaches the diffraction limit. This demonstration sets the stage for the incorporation of other high-efficiency perovskite nanocrystal materials to enable passive multi-frequency conversion imaging systems. [ABSTRACT FROM AUTHOR]

Optical imaging systems play an extremely important role for humans in exploring the world, but the existence of chromatic aberration greatly reduces the imaging ability. Conventional optical systems require the combination of multiple lenses to reduce chromatic aberration, but such a solution is not conducive to the miniaturization and weight reduction of the optical system. In this paper, we design dual-wavelength multilevel diffractive lenses that focus pairs of wavelengths on the same focal plane, using a modified direct-binary-search algorithm to maximize the focusing efficiency. The simulated focusing efficiencies are 72% (92%) and 79% (92%) at the wavelength of 1.064 μm and 1.55 μm, respectively, for the two-dimensional (one-dimensional) ones. Through this approach, the results presented here suggest good focusing performance at two wavelengths, providing a new opportunity for various applications in dual-wavelength imaging systems and lightweight collimators. [ABSTRACT FROM AUTHOR]

A modified fractal spiral forked plate (MFSFP) is proposed to generate three tailorable coplanar optical vortices at multiple focal planes, which consist of two off-axis vortices and one axial vortex. The axial vortex and one low-intensity off-axis vortex can have equal intensity by designing an appropriate spiral-like filter. In addition, the MFSFP has self-similar axial and off-axis optical vortices. Moreover, the tailorable topological charges of two off-axis vortices are related to those of the fractal spiral zone plate (FSZP) and forked grating and the topological charge of the axial vortex is equal to that of the FSZP. In the experiments, based on the interferometric measurement method, the differences between fingers of forked fingers are used to prove the above topological charge transformation rule. The method of constructing the MFSFP is illustrated. The MFSFP is applicable to rotate particles at multiple positions of the different planes simultaneously, increase optical communication capacities and produce multiple images simultaneously. [ABSTRACT FROM AUTHOR]

Contactless manipulation of multi-scale objects using the acoustic vortex (AV) tweezers offers tremendous perspectives in biomedical applications. However, it is still hindered by the weak acoustic radiation force (ARF) and torque (ART) around the vortex center. By introducing the elevation angle to the planar transducers of an N-element ring array, the weak-focused acoustic vortex (WFAV) composed of a main-AV and N paraxial-AVs is constructed to conduct a large-scale object manipulation. Different from the traditional focused AV (FAV) generated by a ring array of concave spherical transducers, a much larger focal region of the WFAV is generated by the main lobes of the planar transducers with the size inversely associated with the elevation angle. With the pressure simulation of the acoustic field, the capability of the rotational object driving in the focal plane for the WFAV is analyzed using the ARF and the ART exerted on an elastic ball based on acoustic scattering. With the experimental system built in water, the generation of the WFAV is verified by the scanning measurements of the acoustic field and the capability of object manipulation is also analyzed by the rotational trapping of floating particles in the focal plane. The favorable results demonstrate the feasibility of large-scale rotational manipulation of objects with a strengthened ART and a reduced acousto-thermal damage to biological tissues, showing a promising prospect for potential applications in clinical practice. [ABSTRACT FROM AUTHOR]

The coupling of fluorescence with surface electromagnetic modes, such as surface plasmons on thin metal films or Bloch surface waves (BSWs) on truncated one-dimensional photonic crystals (1DPCs), are presently utilized for many fluorescence-based applications. In addition to the surface wave, 1DPCs also support other electromagnetic modes that are confined within the 1DPC structure. These internal modes (IMs) have not received much attention for fluorescence coupling due to lack of spatial overlap of their electric fields with the surface bound fluorophores. However, our recent studies have indicated that the fluorescence coupling with IMs occurs quite efficiently. This observed internal mode-coupled emission (IMCE) is (similar to BSW-coupled emission) indeed wavelength dependent, directional and S-polarized. In this paper, we have carried out back-focal plane imaging to reveal that the IMs of 1DPCs can couple with surface bound excited dye molecules, with or without a BSW mode presence. Depending on the emission wavelength, the coupling is observed with BSW and IMs or only IMs of the 1DPC structure. The experimental results are well matching with numerical simulations. The occurrence of IMCE regardless of the availability of BSWs removes the dependence on just the surface mode for obtaining coupled emission from 1DPCs. The observation of IMCE is expected to widen the scope of 1DPCs for surface-based fluorescence sensing and assays. [ABSTRACT FROM AUTHOR]

We present StrayCats , a catalog of NuSTAR stray light observations of X-ray sources. Stray light observations arise for sources 1°–4° away from the telescope pointing direction. At this off-axis angle, X-rays pass through a gap between the optics and aperture stop and so do not interact with the X-ray optics; instead, they directly illuminate the NuSTAR focal plane. We have systematically identified and examined over 1400 potential observations resulting in a catalog of 436 telescope fields and 78 stray light sources that have been identified. The sources identified include historically known persistently bright X-ray sources, X-ray binaries in outburst, pulsars, and type I X-ray bursters. In this paper, we present an overview of the catalog, how we identified the StrayCats sources, and the analysis techniques required to produce high-level science products. Finally, we present a few brief examples of the science quality of these unique data. [ABSTRACT FROM AUTHOR]

Experimental validation of a synthetic aperture imaging technique using a therapeutic random phased array is described, demonstrating the dual nature of imaging and therapy of such an array. The transducer is capable of generating both continuous wave high intensity beams for ablating the tumor and low intensity ultrasound pulses to image the target area. Pulse-echo data is collected from the elements of the phased array to obtain B-mode images of the targets. Since therapeutic arrays are optimized for therapy only with concave apertures having low f-number and large directive elements often coarsely sampled, imaging can not be performed using conventional beamforming. We show that synthetic aperture imaging is capable of processing the acquired RF data to obtain images of the field of interest. Simulations were performed to compare different synthetic aperture imaging techniques to identify the best algorithm in terms of spatial resolution. Experimental validation was performed using a 1 MHz, 256-elements, spherical random phased array with 130 mm radius of curvature. The array was integrated with a research ultrasound scanner via custom connectors to acquire raw RF data for variety of targets. Imaging was implemented using synthetic aperture beamforming to produce images of a rib phantom and ex vivo ribs. The array was shown to resolve spherical targets within ±15 mm of either side of the axis in the focal plane and obtain 3D images of the rib phantom up to ±40 mm of either side of the central axis and at a depth of 3–9 cm from the array surface. The lateral and axial full width half maximum was 1.15 mm and 2.75 mm, respectively. This study was undertaken to emphasize that both therapy and image guidance with a therapeutic random phased array is possible and such a system has the potential to address some major limitations in the existing high intensity focused ultrasound (HIFU) systems. The 3D images obtained with a therapeutic array can be used to identify and locate strong scattering objects aiding to image guidance and treatment planning of the HIFU procedure. [ABSTRACT FROM AUTHOR]

We present the MKID Exoplanet Camera (MEC), a z through J band (800–1400 nm) integral field spectrograph located behind The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) at the Subaru Telescope on Maunakea that utilizes Microwave Kinetic Inductance Detectors (MKIDs) as the enabling technology for high contrast imaging. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. The read noise free, fast time domain information attainable by MKIDs allows for the direct probing of fast speckle fluctuations that currently limit the performance of most high contrast imaging systems on the ground and will help MEC achieve its ultimate goal of reaching contrasts of 10−7 at 2 λ/D. Here we outline the instrument details of MEC including the hardware, firmware, and data reduction and analysis pipeline. We then discuss MEC's current on-sky performance and end with future upgrades and plans. [ABSTRACT FROM AUTHOR]

We describe the evolution and the analysis of the design that led to the development of the Flat-field and wavelength Calibration Unit (FCU) for the Multi-AO Imaging CAmera for Deep Observations (MICADO) instrument. MICADO will be one of the first light instruments of the Extremely Large Telescope. The FCU challenge in terms of calibration is related to the large size of the MICADO entrance and final focal plane, ∼200 mm × 200 mm. Such a focal plane scale and its segmentation in 3 × 3 detectors, require significant design modifications with respect to the calibration units of the current and past generation of instruments. The design analysis and ray tracing calculations are complemented with the test and verification of lab prototypes to assess the reliability of the FCU architecture in terms of flat-field illumination uniformity and signal to noise, spectral calibration line coverage and radial velocity stability of the wavelength solution provided to the instrument. [ABSTRACT FROM AUTHOR]

On large telescopes, the trails produced by MegaConstellation satellites will be significantly defocused due to their close proximity. As a result, their apparent surface brightness will be, under a range of conditions, almost constant during their apparent sweep across the focal plane. This paper derives a few simple relationships and evaluate the impact of such trails on operations of large optical ground based facilities. [ABSTRACT FROM AUTHOR]

Integration of stimulated emission depletion (STED) with digital scanned light-sheet microscopy (DSLM) using a Bessel beam achieves fast, high-resolution and large field of view (FOV) imaging. Here, we report on a combination method of DSLM and STED by using a Bessel beam for excitation and a hollow Gaussian beam for depletion. Owing to the advantages of confined axial distribution around the focal plane for the hollow Gaussian depletion beam, those fluorescence signals from the periphery of the Bessel excitation pattern are depleted by stimulated emission. A super-resolved light sheet with suppressed side lobes is achieved. The numerical simulation results show that the use of the Bessel beam for the excitation and the hollow Gaussian beam for the STED results in a DSLM system with enhanced performance of the axial resolution and image contrast over a moderately large FOV. [ABSTRACT FROM AUTHOR]

Annular-focused beams have attracted attention because of their novel properties and applications in optical trapping, high resolution microscopy, and laser-induced periodic surface structuring. Generation of this beam is very important and necessary. In this article, a novel design of zone plate for forming the annular-focused beams is proposed. The design principle is introduced, and the characteristics of zone plate are analyzed by numerical simulation. The result shows that the zone plate can form a monochromatic ring-shaped intensity distribution in the focal plane. And the design method is also generally suitable for designing the other optical elements to generate the annular-focused beams. [ABSTRACT FROM AUTHOR]

A new imaging method based on phase isolation for the liquid flow measurement of gas–liquid two-phase flow is proposed in this study. A swirler is arranged upstream to isolate two-phase fluids. As the two-phase mixture passes through it, a strong swirl flow is generated. The gas is concentrated into the center of the tube and forms a gas core while the liquid phase is pushed to the tube wall and forms a uniform liquid film, which is where the swirl core-annular flow occurs. After phase isolation, many microbubbles, which are small enough to neglect their body force, appear in the liquid film. These phase-isolation-induced microbubbles are used as tracers to represent the local velocity of the liquid flow. A CCD camera is employed to track the motion of the bubbles at the focal plane and determines the velocity at this position. Then this measured local velocity is converted to the mean velocity of the liquid film by a velocity coefficient based on the similitude principle of the velocity profile. After the flow area of the liquid film is derived from the void fraction measurement by another CCD camera, the flowrate of liquid film is determined. The velocity coefficients which express the relation between local velocity and mean velocity of liquid film are obtained by a calibration experiment. Two conventional industry CCD cameras and corresponding individual LED illuminations constitute the imaging system. The image-processing algorithm was developed using the MATLAB image toolbox. AAir and tap water are used and their superficial velocity are in the range of 3.41 m s−1 ∼ 45.15 m s−1 and 0.022 m s−1 ∼ 0.265 m s−1, respectively. The thickness of liquid film ranges from 72.75 μm to 423.11 μm and the diameter of microbubbles ranges from 11 μm to 35 μm. [ABSTRACT FROM AUTHOR]

We present a systematic study on the control of Cooper minimum (CM) in the high-order harmonics spectra generated during the interaction of Ar gas with ultrashort near-infrared laser pulses. Tailoring the width and depth of CM in argon is demonstrated by changing the gas jet position with respect to the focal plane of focusing lens and by defocusing-assisted phase-matching. We further analyze the influence of single- and two-color laser pump schemes on the appearance of CM. The application of two orthogonally-polarized fields of fundamental radiation and its second harmonic, which is also used to generate controllable yields of odd and even harmonics, led to diminishing the CM in the harmonic spectra. Our experimental findings are supported by theoretical calculations that solve the time-dependent Schrödinger equation in the microscopic domain, and take into account the phase matching in the macroscopic domain. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for uniaxial microscopic three-dimensional (3D) profilometry using a structured light system with dual-telecentric lenses in micro-scale devices. Specifically, a telecentric lens can produce an orthographic view of an object and provide the exact size of objects in the x and y directions. An electronically focus-tunable lens attached to the projector rapidly and precisely changes the focal plane of the projected structured patterns, a camera captures the structured patterns from the same perspective and a computational framework analyzes the relationship between the captured structure images and the drive current of the electronically focus-tunable lens to obtain depth information for each pixel. By replacing the normal lens with telecentric lenses, the proposed method dodges perspective error and makes precision measurement easier. We developed a shadow-free coaxial 3D shape measurement system with dual-telecentric lenses that achieved a spatial resolution of approximately 5.86 µm and 4.08 µm root-mean-square error with a depth range of 1200 µm. [ABSTRACT FROM AUTHOR]

Ray tracing method is used to study the propagation of collimated beams in a liquid–core cylindrical lens (LCL), which has dual functions of diffusion cell and image formation. The diffusion images on the focal plane of the used LCL are simulated by establishing and solving both linear and nonlinear ray equations, the calculated results indicate that the complex imaging results of LCL in inhomogeneous media can be treated by the law of ray propagation in homogeneous media under the condition of small refractive index gradient of diffusion solution. Guided by the calculation conditions, the diffusion process of triethylene glycol aqueous solution is experimentally studied at room temperature by using the LCL in this paper. The spatial and temporal concentration profile Ce(z, t) of diffusion solution is obtained by analyzing diffusion image appearing on the focal plane of the LCL; Then, the concentration-dependent diffusion coefficient is assumed to be a polynomial D(C) = D0 × (1 + α1C + α2C2 + α3C3 + ⋅). The finite difference method is used to solve the Fick diffusion equation for calculating numerically the concentration profiles Cn(z, t). The D(C)of triethylene glycol aqueous solution is obtained by comparing the Cn(z, t) with Ce(z,t). Finally, the obtained polynomial D(C) is used to calculate the refractive index profiles nn(z,t)s of diffusion solution in the used LCL. Based on the ray propagation law in inhomogeneous media and the calculated n(z,t), the ray tracing method is used again to simulate the dynamic images of the whole experimental diffusion process to varify the correctness of the calculated D(C). The method presented in this work opens up a new way for both measuring and verifying the concentration-dependent liquid diffusion coefficients. [ABSTRACT FROM AUTHOR]

Weak gravitational lensing has emerged as a leading probe of the growth of cosmic structure. However, the shear signal is very small and accurate measurement depends critically on our ability to understand how non-ideal instrumental effects affect astronomical images. The Wide-Field Infrared Survey Telescope (WFIRST) will fly a focal plane containing 18 Teledyne H4RG-10 near-infrared detector arrays, which present different instrument calibration challenges from previous weak lensing observations. Previous work [Paper I: Hirata & Choi, PASP, 132, 014501 (2020); and Paper II: Choi & Hirata, PASP, 132, 014502 (2020)] has shown that correlation functions of flat field images, including cross-correlations between different time slices that are enabled by the non-destructive read capability of the infrared detectors, are effective tools for disentangling linear and nonlinear inter-pixel capacitance (IPC) and the brighter-fatter effect (BFE). Here we present a Fourier-domain treatment of the flat field correlations, which allows us to expand the previous formalism to all orders in IPC, BFE, and classical nonlinearity. We show that biases in simulated flat field analyses in Paper I are greatly reduced through the use of this formalism. We then apply this updated formalism to flat field data from three WFIRST flight candidate detectors, and explore the robustness to variations in the analysis. We find that the BFE is present in all three detectors, and that its contribution to the flat field correlations dominates over the nonlinear IPC, in accordance with the results from Paper II on a development detector. The magnitude of the BFE is such that the effective area of a pixel is increased by (3.54 ± 0.03) × 10−7 for every electron deposited in a neighboring pixel (sensor chip assembly [SCA] 20829, statistical error, not IPC-deconvolved). We compare IPC maps from flat field autocorrelation measurements to those obtained from the single pixel reset method and find a median difference of 0.113% for SCA 20829. After further diagnosis of this difference, we ascribe it largely to an additional source of cross-talk, the vertical trailing pixel effect, and recommend further work to develop a model for this effect. These results represent a significant step toward calibration of the non-ideal effects in WFIRST detectors. [ABSTRACT FROM AUTHOR]

Measurement of surface plasmon and surface wave propagation is important for the operation and characterization of sensors and microscope systems. One challenge is to perform these measurements both quickly and with good spatial resolution without any modification to the sample surface. This paper addresses these issues by projecting an image of the field excited from a defocused sample to a magnified image plane. By carefully analysing the intensity distribution in this plane the properties of the surface waves generated on the sample surface can be determined. This has the advantage over previous techniques that the data can be obtained in a single shot without any changes to the focal position of the sample. Equally importantly, we show the method measures the local properties of the sample at well-defined positions, whereas other methods such as direct observation of the back focal plane average the properties over the propagation length of the surface waves. [ABSTRACT FROM AUTHOR]

Fourier ptychographic microscopy (FPM), by using a LED array as its light source and each LED being lit up sequentially, can recover a high resolution (HR) and large field of view image from a sequence of low resolution (LR) images. It is difficult to obtain a perfect high resolution color image by a monochrome camera because of non-overlapping focal planes of different color channels resulting from the residual chromatic aberration of the microscopic objective. In this paper, a kind of method, based on symmetrical LED illumination and wavelength multiplexing, is applied in a FPM system to collect LR images and recover HR color images. Compared with single LED illumination, symmetrical illumination has higher defocus tolerance. It is proven by simulated and experimental results that higher-quality HR color images can be obtained based on wavelength multiplexing and symmetrical illumination by a monochrome camera when defocus or chromatic aberration exist. It is demonstrated that symmetrical illumination is helpful in chromatic aberration correction in color FPM imaging. [ABSTRACT FROM AUTHOR]

We investigate a family of radially polarized Pearcey–Gauss vortex beams (RPPGVBs), obtain the general propagation expressions of an RPPGVB, and study the intensity distribution, phase pattern, spin currents as well as the orbital currents when the RPPGVB propagates in free space. The focal plane and the intensity of the focal point can be adjusted by changing the position of the vortex and the scaling factors. We also investigate how the waist size influences the propagation properties. [ABSTRACT FROM AUTHOR]

The continual push to directly image exoplanets at lower masses and closer separations orbiting around bright stars remains limited by both quasi-static and residual adaptive optics aberration. In previous papers we have proposed a modification of the self-coherent camera (SCC) design to address both of these limitations, called the Fast Atmospheric SCC Technique (FAST). In this paper we introduce an additional modification to the FAST focal plane mask design, including the existing Tip/tilt and Gaussian components and adding a charge four Vortex (TGV) component. In addition to boosting SCC fringe signal-to-noise ratio (S/N) as in our previous design, we show that the FAST TGV mask is also optimized to reach high contrast at separations closer to the star. In this paper we use numerical simulations to consider the performance improvement on correcting quasi-static aberration using this new mask compared to the previously proposed Tip/tilt+Gaussian mask. Using active deformable mirror control to generate a calibrated half dark hole improves contrast by a factor of about 200 at 2–5 λ/D and up to a factor of 10 at 5–20 λ/D. The new methodology presented in this paper, now simultaneously considering both contrast and fringe S/N, opens the door to a new ideology of coronagraph design, where the coronagraph is now considered in duality as both a diffraction attenuator and a wavefront sensor. [ABSTRACT FROM AUTHOR]

The formation of twin images in digital inline holography (DIH) prevents the placement of the focal plane in the center of a sample volume for DIH-based particle tracking velocimetry (DIH-PTV) with a single camera. As a result, it is challenging to apply DIH-PTV for flow measurements in large-scale laboratory facilities or many field applications where it would otherwise be desirable due to the low cost and compact setup. Here we introduce holographic astigmatic PTV (HAPTV) by inserting a cylindrical lens in the optical setup of DIH-PTV, generating distorted holograms. Such distortion is subsequently utilized in a customized reconstruction algorithm to distinguish tracers positioned on different sides of the focal plane which can in turn be placed in the middle of a sample volume. Our HAPTV approach is calibrated under high (1 µm pixel−1) and low (10 µm pixel−1) magnifications with an error standard deviation of 4.2 µm (one particle diameter) and 120.7 µm (~5 times the particle diameter), respectively. We compare the velocity field of a laminar jet flow obtained using HAPTV and conventional PIV to illustrate the accuracy of the technique when applied to practical flow measurement applications. The work demonstrates that HAPTV improves upon the depth of field of conventional astigmatic PTV and enables the implementation of DIH-based PTV for in situ applications. [ABSTRACT FROM AUTHOR]

We study the generation of high-harmonic beams by the non-collinear wave mixing of two circularly or elliptically polarized fundamental beams. Changing the ellipticity of the two fundamental beams changes the electric field structure in the focal plane, generating multiple high harmonics beamlets. We show that the ellipticity dependence of the harmonic dipole modulates the near-field harmonic intensity, resulting in the diffraction of the generated harmonics in the far-field. [ABSTRACT FROM AUTHOR]

The Andrejic focal extent measures, based on intensity, are an effective area in the focal plane, and an effective length of the focal region. The Cauchy–Schwartz inequality then provides lower bounds for both the transverse and longitudinal extents. Two families of monochromatic scalar beams, which share a tight-focus limit, are compared in their transverse and longitudinal focal extents. Both the beam families are characterized by a dimensionless parameter where is the wavenumber, and is a length. As increases from zero the transverse and longitudinal extents of both families increase monotonically. For large , the longitudinal extent becomes proportional to the length and the transverse localization is the same as for the Gaussian beam. For small , the two families have a confluent limit, the proto-beam. The Andrejic transverse extent lower bound is reached by the proto-beam, but the longitudinal extent lower bound is exceeded by the factor A hypothetical beam which reaches the longitudinal extent lower bound is shown to be non-physical. [ABSTRACT FROM AUTHOR]

The conical diffraction (CD) of a wave propagating along the optical axis of a biaxial crystal is an intriguing phenomenon with current applications including imaging and optical communications. The emerging light can have a fractional or integer orbital angular momentum (OAM) along the propagation direction per unit thickness of a transverse section. The measurement of the OAM of a beam is not an easy task, particularly for non-integer values. We operated the CD of 1053 and 1047 nm beams with a KGd(WO2)4 crystal, in various input and output polarization states. Then, the sum-frequency was obtained with a KTiOPO4 crystal located near the second Raman spike. The integer or fractional OAM of both the fundamental and sum-frequency waves were visualized with the cylindrical lens method. All the experimental patterns, far field, near field and field in the focal plane of the cylindrical lens, are quite well described by a self-consistent model based on plane wave propagation and their interferences. The sum of the OAM due to quadratic nonlinear conversion is evidenced from experimental and calculated patterns. [ABSTRACT FROM AUTHOR]

We describe the layout and unique features of the focal plane system for MIRI. We begin with the detector array and its readout integrated circuit (combining the amplifier unit cells and the multiplexer), the electronics, and the steps by which the data collection is controlled and the output signals are digitized and delivered to the JWST spacecraft electronics system. We then discuss the operation of this MIRI data system, including detector readout patterns, operation of subarrays, and data formats. Finally, we summarize the performance of the system, including remaining anomalies that need to be corrected in the data pipeline. [ABSTRACT FROM AUTHOR]

Developments in coronagraph technology are close to achieving the technical requirements necessary to observe the faint signal of an Earth-like exoplanet in monochromatic light. An important remaining technological challenge is to achieve high contrast in broadband light. coronagraph bandwidth is largely limited by chromaticity of the focal plane mask, which is responsible for blocking the stellar PSF. The size of a stellar PSF scales linearly with wavelength; ideally, the size of the focal plane mask would also scale with wavelength. A conventional hard-edge focal plane mask has a fixed size, normally sized for the longest wavelength in the observational band to avoid starlight leakage. The conventional mask is oversized for shorter wavelengths and blocks useful discovery space. We present a new focal plane mask which operates conceptually as an opaque disk occulter, but uses a phase mask technique to improve performance and solve the "size chromaticity" problem. This achromatic focal plane mask would maximize the potential planet detection space without allowing starlight leakage to degrade the system contrast. Compared with a conventional opaque disk focal plane mask, the achromatic mask allows coronagraph operation over a broader range of wavelengths and allows the detection of exoplanets closer to their host star. We present the generalized design for the achromatic focal plane mask, implementation within the Subaru Coronagraph Extreme Adaptive Optics instrument, and laboratory results which demonstrate the sizescaling property of the mask. [ABSTRACT FROM AUTHOR]

Bloch surface waves (BSWs) on one-dimensional photonic crystals (1DPCs) have been used to beam the fluorescence emission from the dye molecules. All dielectric 1DPC displays its low propagating loss, narrow resonance and the absence of absorption or quenching. In this paper, back focal plane imaging reveals that in addition to the BSW mode, a guided mode and a cavity mode also exist in the 1DPC which all couple with the excited dye molecules. The appearance of these modes is sensitive to the wavelength of the fluorescence and alters the beaming effect by the 1DPC. Numerical simulations verify the existence of these modes which are consistent with the experimental results. Comparisons between the Bloch surface wave coupled emission and surface plasmon coupled emission are also presented for a clearer understanding of the multilayered film enabled directional emission. [ABSTRACT FROM AUTHOR]

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li. [ABSTRACT FROM AUTHOR]