Lobster-eye X-ray Research Articles

Comprehensive characterization and simulation of the point spread function of lobster eye X-ray micro pore optics

Lobster eye micro pore optics has been extensively researched, developed, and experimented with over the past few decades since its proposal by Angel in 1979. The lobster eye X-ray telescope represents the next generation of X-ray time-domain astronomy. This study presents a novel semi-analytical numerical model for simulating and studying the optical performance of micro pore X-ray optics based on geometric physical models, channel errors, and Fresnel reflectance. The numerical method accurately and rapidly models the X-ray point-spread function through millions of square microchannels. Soft X-ray testing validates the semi-analytical numerical model, which simulates common channel errors in lobster eye optics manufacturing. The X-ray results demonstrated that tilt and shear channel errors significantly impacted the point spread function, which is consistent with simulation outcomes and has a significant guiding value for the subsequent process improvement.

Fires in the deep: The luminosity distribution of early-time gamma-ray-burst afterglows in light of the Gamow Explorer sensitivity requirements

Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift ($z$), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights with simple featureless power-law spectra that can be used to spectrally fingerprint the intergalactic medium and host galaxy during the period of reionization. Future missions such as Gamow Explorer (hereafter )\ are being proposed to unlock this potential by increasing the rate of identification of high-$z$ ($z>5$) GRBs in order to rapidly trigger observations from $6-10$ m ground telescopes, the James Webb Space Telescope (JWST), and the upcoming Extremely Large Telescopes (ELTs). was proposed to the NASA 2021 Medium-Class Explorer (MIDEX) program as a fast-slewing satellite featuring a wide-field lobster-eye X-ray telescope (LEXT) to detect and localize GRBs with arcminute accuracy, and a narrow-field multi-channel photo-$z$ infrared telescope (PIRT) to measure their photometric redshifts for $>80<!PCT!>$ of the LEXT detections using the Lyman-alpha dropout technique. We use a large sample of observed GRB afterglows to derive the PIRT sensitivity requirement. We compiled a complete sample of GRB optical--near-infrared (optical--NIR) afterglows from 2008 to 2021, adding a total of 66 new afterglows to our earlier sample, including all known high-$z$ GRB afterglows. This sample is expanded with over 2837 unpublished data points for 40 of these GRBs. We performed full light-curve and spectral-energy-distribution analyses of these afterglows to derive their true luminosity at very early times. We compared the high-$z$ sample to the comparison sample at lower redshifts. For all the light curves, where possible, we determined the brightness at the time of the initial finding chart of at different high redshifts and in different NIR bands. This was validated using a theoretical approach to predicting the afterglow brightness. We then followed the evolution of the luminosity to predict requirements for ground- and space-based follow-up. Finally, we discuss the potential biases between known GRB afterglow samples and those to be detected by We find that the luminosity distribution of high-$z$ GRB afterglows is comparable to those at lower redshift, and we therefore are able to use the afterglows of lower-$z$ GRBs as proxies for those at high $z$. We find that a PIRT sensitivity of $15\ (21 mag AB) in a 500 s exposure simultaneously in five NIR bands within 1000s of the GRB trigger will meet the mission requirements. Depending on the $z$ and NIR band, we find that between 75<!PCT!> and 85<!PCT!> of all afterglows at $z>5$ will be recovered by at $5 detection significance, allowing the determination of a robust photo-$z$. As a check for possible observational biases and selection effects, we compared the results with those obtained through population-synthesis models, and find them to be consistent. and other high-$z$ GRB missions will be capable of using a relatively modest 0.3m onboard NIR photo-$z$ telescope to rapidly identify and report high-$z$ GRBs for further follow-up by larger facilities, opening a new window onto the era of reionization and the high-redshift Universe.

Preliminary optical tests of lobster eye X-ray optics prototype for nano-satellite missions based on new technology

Preliminary optical tests of lobster eye X-ray optics prototype for nano-satellite missions based on new technology

Study on the optical properties of Iridium-coated lobster eye X-ray micro pore optics

Lobster eye micro pore optics (MPO) has been extensively researched, developed, and experimented over the past few decades since Angel proposed it in 1979. The inner wall of the square channel was coated with high-density Iridium metal, which is used to improve X-ray reflectivity, an essential feature of lobster-eye X-ray optics. In this work, we successfully used atomic layer deposition technology (ALD) to coat a 21 ± 1 nm thick iridium metal film. We used SEM, AFM, EDS, ZYGO interferometer, and X-ray technology to investigate the optical properties of Iridium-coated lobster eye optics. Initially, we discovered that the roughness of the inner wall and spherical surface of the device would worsen due to the high deposition temperature. At the voltage was 5 kV, the current was 0.1 mA. The X-ray test results reveal that when the deposition temperature reached 395 °C, the angular resolution dropped nearly 12.5%, and the X-ray effective area was reduced by about 25%.

Target Detection Framework for Lobster Eye X-Ray Telescopes with Machine-learning Algorithms

Lobster eye telescopes are ideal monitors to detect X-ray transients because they could observe celestial objects over a wide field of view in the X-ray band. However, images obtained by lobster eye telescopes are modified by their unique point-spread functions, making it hard to design a high-efficiency target detection algorithm. In this paper, we integrate several machine-learning algorithms to build a target detection framework for data obtained by lobster eye telescopes. Our framework would first generate two 2D images with different pixel scales according to positions of photons on the detector. Then, an algorithm based on morphological operations and two neural networks would be used to detect candidates of celestial objects with different flux from these 2D images. Finally, a random forest algorithm will be used to pick up final detection results from candidates obtained by previous steps. Tested with simulated data of the Wide-field X-ray Telescope on board the Einstein Probe, our detection framework could achieve over 94% purity and over 90% completeness for targets with flux more than 3 mcrab (9.6 × 10−11 erg cm−2 s−1) and more than 94% purity and moderate completeness for targets with lower flux at acceptable time cost. The framework proposed in this paper could be used as references for data processing methods developed for other lobster eye X-ray telescopes.

An effective system for evaluating the performance of micro pore optics used for lobster eye X-ray telescope

Fabricating and evaluating the high angular resolution micro pore optics (MPO) used for the Lobster eye X-ray telescope has been challenging and essential since its advent. We developed two sets of X-ray test equipment suitable for industrial batch production, which evaluate the optical quality of flat and spherical chips. At the voltage was 2 kV, the current was 0.1 mA, and the best angular resolution of the flat and spherical chip was 2.7 arcmins and 3.4 arcmins, respectively. The simulation results show that the tilt and distort channel errors mainly affected the shape of the point spread function, similar to the X-ray measurement results.

Fabrication and Performance of Lobster Eye X-Ray Micro Pore Optics with the Ultra-high Aspect Ratio

Since the idea of bionic Lobster eye micropore optics was put forward, the possibility of focusing hard X-rays by this new lightweight X-ray optics has been proposed. Limited by the technological conditions of the aspect ratio (≥500), low surface roughness (≤1 nm) and the difficulty of applying metal coatings inside such narrow square channels, the high quality of these new optics have not been realized. This work demonstrates the test results for an Ultra-high aspect ratio (500:1) of iridium-coated with microchannel plate technology and atomic layer deposition technology. The sidewalls of the square channel are smoothed with a special acid-base treatment and the Root-Mean-Square of the inner wall was 0.52 ± 0.1 nm in 3 μm × 3 μm scale roughness, such that they work well as X-ray mirrors. The thickness of the metal iridium film layer was 19 nm. At the working voltage of 2 kV, the current was 0.1 mA and the angular resolution of the slumped chip in horizontal and vertical directions was 3.′9 and 4.′2, respectively. The simulation results were in good agreement with the X-ray test results.

Supernova Shock Breakout/Emergence Detection Predictions for a Wide-field X-Ray Survey

There are currently many large-field surveys that are operational and are being planned including the powerful Vera C. Rubin Observatory Legacy Survey of Space and Time. These surveys will increase the number and diversity of transients dramatically. However, for some transients, like supernovae (SNe), we can gain more understanding by directed observations (e.g., shock breakout and γ-ray detections) than by simply increasing the sample size. For example, the initial emission from these transients can be a powerful probe of these explosions. Upcoming ground-based detectors are not ideally suited to observing the initial emission (shock emergence) of these transients. These observations require a large field-of-view X-ray mission with a UV follow-up within the first hour of shock breakout. The emission in the first 1 hr to even 1 day provides strong constraints on the stellar radius and asymmetries in the outer layers of stars, the properties of the circumstellar medium (e.g., inhomogeneities in the wind for core-collapse SNe and accreting companions in thermonuclear SNe), and the transition region between these two areas. This paper describes a simulation for the number of SNe that could be seen by a large field-of-view lobster-eye X-ray and UV observatory.

Small Spacecraft Payload Study for X-ray Astrophysics including GRB Science

This paper presents microsatellite spacecraft payload study for prompt observation of transient astrophysical objects in X-ray energy range. By combining telescope concepts and miniaturized detectors, the small spacecraft will be able to probe the X-ray temporal emissions of bright events such as Gamma-Ray Bursts (GRBs), X-ray transients or the electromagnetic counterparts of Gravitational Wave Events (GWEs), but also short and long term observations of other types of variable X-ray sources. The spacecraft is based on the CubeSat nanosatellite platform with a volume of 16U. The spacecraft carries two types of X-ray telescopes onboard. The first is intended for X-ray transient monitoring and localization, and the second for detailed spectroscopic observation. The X-ray monitor/localization telescope with wide field of view of several arc degrees is used for localization and flux measurement of X-ray transients, as well as for permanent monitoring of Galactic center area. This telescope is based on Lobster Eye X-ray optics together with pixel detector based on the Timepix3 Quad detector. Rapid follow-up observation by soft X-ray spectroscopy is enabled by a second X-ray spectroscopic telescope with limited FOV (Field of View) of several arcmins with no spatial and/or angular resolution. The spectroscopic telescope uses condenser optics based on replicated parabolic total reflection system (or, alternatively, Wolter system) and a Ketek X-ray SDD detector with energy resolution of about 130 eV as a detector. In addition to technical and instrumental aspects, observational strategy and astrophysical issues and justifications are also addressed in the paper.

Simulation and Test of Effective Area of Lobster Eye X-Ray Optical Device

Simulation and Test of Effective Area of Lobster Eye X-Ray Optical Device

Navigation Grade MEMS IMU for A Satellite.

This paper presents a navigation grade micro-electromechanical system (MEMS) inertial measurement unit (IMU) that was successfully applied for the first time in the Lobster-Eye X-ray Satellite in July 2020. A six-axis MEMS gyroscope redundant configuration is adopted in the unit to improve the performance through mutual calibration of a set of two-axis gyroscopes in the same direction. In the paper, a satisfactory precision of the gyroscope is achieved by customized and self-calibration gyroscopes whose parameters are adjusted at the expense of bandwidth and dynamics. According to the in-orbit measured data, the MEMS IMU provides an outstanding precision of better than 0.02 °/h (1σ) with excellent bias instability of 0.006 °/h and angle random walk (ARW) of around 0.003 °/h1/2. It is the highest precision MEMS IMU for commercial aerospace use ever publicly reported in the world to date.

Study on the optical properties of Angel Lobster eye X-ray flat micro pore optical device

Micro pore optical (MPO) device is a novel X-ray optical component with a unique 4π solid-angle focusing capability and large effective area for specified weight ratio, which meet the requirements of the applications in modern X-ray astronomy. The focusing performance of flat MPO is a key factor affecting the detection capability of the finished device used for Lobster eye X-ray telescope. In this paper, to study the optical properties of the flat plate, we performed both numerical simulation and experimental measurements. The measured focal distance was 3650 mm ± 10 mm. The full width at half maximum of the measured focal spot in the vertical and horizontal direction was 1.83 mm and 3.27 mm, respectively. And the corresponding angular resolution was 1.73 arcmins and 3.08 arcmins. The simulation results showed that these two kinds of channel errors have a great influence on the point spread function of this device, which was in good agreement with the test results.

In-Orbit Commissioning of Czech Nanosatellite VZLUSAT-1 for the QB50 Mission with a Demonstrator of a Miniaturised Lobster-Eye X-Ray Telescope and Radiation Shielding Composite Materials

This paper presents the results of in-orbit commissioning of the first Czech technological CubeSat satellite of VZLUSAT-1. The 2U nanosatellite was designed and built during the 2013 to 2016 period. It was successfully launched into Low Earth Orbit of 505 km altitude on June 23, 2017 as part of international mission QB50 onboard a PSLV C38 launch vehicle. The satellite was developed in the Czech Republic by the Czech Aerospace Research Centre, in cooperation with Czech industrial partners and universities. The nanosatellite has three main payloads. The housing is made of a composite material which serves as a structural and radiation shielding material. A novel miniaturized X-Ray telescope with lobster-eye optics and an embedded Timepix detector represents the CubeSat’s scientific payload. The telescope has a wide field of view. VZLUSAT-1 also carries the FIPEX scientific instrument as part of the QB50 mission for measuring the molecular and atomic oxygen concentration in the upper atmosphere.

基于Angel型龙虾眼X射线透镜的数值模拟

基于Angel型龙虾眼X射线透镜的数值模拟

Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

High-redshift Gamma-Ray Bursts (GRBs) beyond redshift $\sim6$ are potentially powerful tools to probe the distant early Universe. Their detections in large numbers and at truly high redshifts call for the next generation of high-energy wide-field instruments with unprecedented sensitivity at least one order of magnitude higher than the ones currently in orbit. On the other hand, follow-up observations of the afterglows of high-redshift GRBs and identification of their host galaxies, which would be difficult for the currently operating telescopes, require new, extremely large facilities of at multi-wavelengths. This chapter describes future experiments that are expected to advance this exciting field, both being currently built and being proposed. The legacy of Swift will be continued by SVOM, which is equipped with a set of space-based multi-wavelength instruments as well as and a ground segment including a wide angle camera and two follow-up telescopes. The established Lobster-eye X-ray focusing optics provides a promising technology for the detection of faint GRBs at very large distances, based on which the {THESEUS}, {Einstein Probe} and other mission concepts have been proposed. Follow-up observations and exploration of the reionization era will be enabled by large facilities such as {SKA} in the radio, the 30m class telescopes in the optical/near-IR, and the space-borne {WFIRST} and {JWST} in the optical/near-IR/mid-IR. In addition, the X-ray and $\gamma$-ray polarization experiment POLAR is also introduced.

A novel lobster-eye imaging system based on Schmidt-type objective for X-ray-backscattering inspection.

This paper presents a novel lobster-eye imaging system for X-ray-backscattering inspection. The system was designed by modifying the Schmidt geometry into a treble-lens structure in order to reduce the resolution difference between the vertical and horizontal directions, as indicated by ray-tracing simulations. The lobster-eye X-ray imaging system is capable of operating over a wide range of photon energies up to 100 keV. In addition, the optics of the lobster-eye X-ray imaging system was tested to verify that they meet the requirements. X-ray-backscattering imaging experiments were performed in which T-shaped polymethyl-methacrylate objects were imaged by the lobster-eye X-ray imaging system based on both the double-lens and treble-lens Schmidt objectives. The results show similar resolution of the treble-lens Schmidt objective in both the vertical and horizontal directions. Moreover, imaging experiments were performed using a second treble-lens Schmidt objective with higher resolution. The results show that for a field of view of over 200 mm and with a 500 mm object distance, this lobster-eye X-ray imaging system based on a treble-lens Schmidt objective offers a spatial resolution of approximately 3 mm.

GRBs and Lobster Eye X-Ray Telescopes

A large majority of GRBs exhibit X-ray emission. In addition, a dedicated separate group of GRB, the XRFs, exists which emission dominates in the X-ray spectral range. And the third group of GRB related objects (yet hypothetical) are the group of off-axis observed GRBs (orphan afterglows). These facts justify the consideration of an independent experiment for monitoring, detection and analyses of GRBs and others fast X-ray transients in X-rays. We will present and discuss such experiment based on wide-field X-ray telescopes of Lobster Eye type. We show that the wide field and fine sensitivity of Lobster Eye X-ray All-Sky Monitor make such instruments important tools in study of GRBs.

Tests of lobster eye optics for small space X-ray telescope

The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it can be a convenient approach for the construction of space all-sky X-ray monitors. We present preliminary results of tests of prototype lobster eye X-ray optics in quasi parallel beam full imaging mode conducted using the 35 m long X-ray beam-line of INAF-OAPA in Palermo (Italy). X-ray images at the focal plane have been taken with a microchannel plate (MCP) detector at several energy values from 0.3 to 8 keV. The gain, the field of view and the angular resolution have been measured and compared with theoretical values.

Astrophysics with LOBSTER

We report on astrophysical aspects of fully innovative very wide-field X-ray telescopes with high sensitivity. The prototypes are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study of various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc.

GRB and XRF analyses with Lobster-Eye X-ray telescopes

The X-ray emission has been confirmed for majority of Gamma-Ray Bursts (GRBs). This means that the GRBs and also X-ray Flashes (XRF) can be detected not only in gamma-rays but also in the X-rays, preferably with X-Ray all-sky monitors or wide-field instruments. We present and discuss the idea to use newly designed and developed wide-field Lobster-Eye X-ray telescopes for this purpose.