Average Beam Research Articles

Initial Steps Towards a Clinical FLASH Radiotherapy System: Pediatric Whole Brain Irradiation with 40 MeV Electrons at FLASH Dose Rates.

In this work, we investigated the delivery of a clinically acceptable pediatric whole brain radiotherapy plan at FLASH dose rates using two lateral opposing 40-MeV electron beams produced by a practically realizable linear accelerator system. The EGSnrc Monte Carlo software modules, BEAMnrc and DOSXYZnrc, were used to generate whole brain radiotherapy plans for a pediatric patient using two lateral opposing 40-MeV electron beams. Electron beam phase space files were simulated using a model of a diverging beam with a diameter of 10 cm at 50 cm SAD (defined at brain midline). The electron beams were collimated using a 10-cm-thick block composed of 5 cm of aluminum oxide and 5 cm of tungsten. For comparison, a 6-MV photon plan was calculated with the Varian AAA algorithm. Electron beam parameters were based on a novel linear accelerator designed for the PHASER system and powered by a commercial 6-MW klystron. Calculations of the linear accelerator's performance indicated an average beam current of at least 6.25 µA, providing a dose rate of 115 Gy/s at isocenter, high enough for cognition-sparing FLASH effects. The electron plan was less homogenous with a homogeneity index of 0.133 compared to the photon plan's index of 0.087. Overall, the dosimetric characteristics of the 40-MeV electron plan were suitable for treatment. In conclusion, Monte Carlo simulations performed in this work indicate that two lateral opposing 40-MeV electron beams can be used for pediatric whole brain irradiation at FLASH dose rates of >115 Gy/s and serve as motivation for a practical clinical FLASH radiotherapy system, which can be implemented in the near future.

Dissipation of electron-beam-driven plasma wakes

Metre-scale plasma wakefield accelerators have imparted energy gain approaching 10 gigaelectronvolts to single nano-Coulomb electron bunches. To reach useful average currents, however, the enormous energy density that the driver deposits into the wake must be removed efficiently between shots. Yet mechanisms by which wakes dissipate their energy into surrounding plasma remain poorly understood. Here, we report picosecond-time-resolved, grazing-angle optical shadowgraphic measurements and large-scale particle-in-cell simulations of ion channels emerging from broken wakes that electron bunches from the SLAC linac generate in tenuous lithium plasma. Measurements show the channel boundary expands radially at 1 million metres-per-second for over a nanosecond. Simulations show that ions and electrons that the original wake propels outward, carrying 90 percent of its energy, drive this expansion by impact-ionizing surrounding neutral lithium. The results provide a basis for understanding global thermodynamics of multi-GeV plasma accelerators, which underlie their viability for applications demanding high average beam current.

Initial Clinical Experience Treating Patients With Lung Cancer on a 6MV-Flattening-Filter-Free O-Ring Linear Accelerator.

IntroductionModern technologies, like intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), have improved the therapeutic ratio of thoracic radiotherapy (TRT) for lung cancer (LC). Halcyon™ (Varian Medical Systems, Palo Alto, CA, USA), a novel 6MV-flattening-filter-free O-ring linear accelerator (6X-FFF ORL), was designed to deliver IMRT and VMAT with greater speed than a C-arm linac. Herein, we report our initial clinical experience treating patients with LC on this linac.MethodsAll patients who received TRT for LC on the 6X-FFF ORL at our institution were retrospectively identified. Patients’ clinicopathologic data, radiotherapy details, early disease-control and toxicity outcomes, dosimetric data, couch corrections, and treatment times are reported.ResultsBetween 10/2018-12/2019, 30 consecutive patients (median age 66 years, range 54-94 years) received definitive or post-operative TRT for LC (median 66 Gy/33 fractions; range 5-70 Gy/2-37 fractions) following four-dimensional computed tomography (CT) simulation (97%) using daily kilovoltage KV cone-beam CT (CBCT) (100%) on a 6X-FFF ORL for non-small cell LC (84%) or small cell LC (16%), with 53% receiving VMAT, 43% receiving static-field IMRT, and 77% receiving concurrent systemic therapy. All plans were approved through institutional peer review. The average three-dimensional vector couch correction based on CBCT guidance was 0.90 ± 0.50 cm. The average beam-on and beam on plus CBCT times were 1.7 ± 1.1 min, and 5.0 ± 3.2 min, respectively. Grade 3 dyspnea and fatigue occurred in 3% and 3% of patients, respectively. There were no grade ≥4 toxicities.ConclusionIn this first clinical report of TRT for LC on a 6X-FFF ORL, daily CBCT-guided treatment was fast and safe with respect to dosimetry and clinical outcomes. Thus, use of this linac for TRT may increase LC patient throughput without a detriment in radiotherapy quality.

Radiation Generation with an Existing Demonstrator of an Energy-Recovery Continuous-Wave Superconducting RF Accelerator

Over the past decades, many accelerator laboratories have put much effort into the development of compact energy-recovery linac (ERL) demonstrators to verify various physical and technical aspects of the generation, acceleration, transport and energy recovery of high brightness and high average current electron beams in a superconducting radio-frequency (SRF) linear accelerator. Beyond these goals, the ERL demonstrator also offers unique opportunities to study novel schemes for THz and X-ray radiation generation. In this paper, we discuss feasible options for schemes generating THz and X-ray radiation at low-energy continuous-wave (CW) SRF ERL demonstrators such as the bERLinPro accelerator.

Tuning the ultralow β* optics at the KEK Accelerator Test Facility 2

For future linear colliders, a nanometer-scale beam size at the interaction point (IP) is one of the most challenging technical aspects. To explore the feasibility of a final focus system with a high chromaticity level, comparable to that of the Compact Linear Collider, the ultralow ${\ensuremath{\beta}}^{*}$ optics has been proposed and tuned at the KEK Accelerator Test Facility 2. In this paper, the recent experimental results are presented, which demonstrate the capability of achieving and stabilizing a vertical average beam size of 60 nm and below at the virtual IP. The observed vertical beam size is about 20 nm above the numerical predictions in the presence of static and dynamic imperfections. We interpret this discrepancy as beam size growth due to multipole fields, beam jitters and wakefield effects, and diagnostic errors.

Economical evaluation of radiation processing with high-intensity X-rays

Abstract X-rays application for radiation processing was introduced to the industrial practice, and in some circumstances is found to be more economically competitive, and offer more flexibility than gamma sources. Recent progress in high-power accelerators development gives opportunity to construct and apply reliable high-power electron beam to X-rays converters for the industrial application. The efficiency of the conversion process depends mainly on electron energy and atomic number of the target material, as it was determined in theoretical predictions and confirmed experimentally. However, the lower price of low-energy direct accelerators and their higher electrical efficiency may also have certain influence on process economy. There are number of auxiliary parameters that can effectively change the economical results of the process. The most important ones are as follows: average beam power level, spare part cost, and optimal shape of electron beam and electron beam utilization efficiency. All these parameters and related expenses may affect the unit cost of radiation facility operation and have a significant influence on X-ray process economy. The optimization of X-rays converter construction is also important, but it does not depend on the type of accelerator. The article discusses the economy of radiation processing with high-intensity of X-rays stream emitted by conversion of electron beams accelerated in direct accelerator (electron energy 2.5 MeV) and resonant accelerators (electron energy 5 MeV and 7.5 MeV). The evaluation and comparison of the costs of alternative technical solutions were included to estimate the unit cost of X-rays facility operation for average beam power 100 kW.

Mitigation of beam losses in LANSCE linear accelerator

The LANSCE accelerator has been in operation for nearly five decades. During this period, it was transformed from a 0.8 MW average proton beam power machine used primarily for the study of meson physics, to a multi-user high-power facility for fundamental research and national security applications, concurrently delivering beams to five distinct experimental areas. Minimization of beam losses in multi-beam application is a key issue for effective operation of accelerator facility. This paper summarizes recent experimental results in understanding and lowering of beam losses in LANSCE linear accelerator and high-energy beam transport lines.

Design of an energy analyzer for highly charged Ions HCI beams

The measurements of the energy spread and the average beam energy for highly charged ion (HCI) beams, such as those delivered from EBIS charge breeder ion source and ECR ion source, demand the development of an energy analyzer of highest measurement efficiency. A new prototype of a compact analyzer called retarding field energy analyzer RFEA capable to handle all kinds of HCI beams at RISP project is being designed. The RFEA's efficiency measurement has been evaluated via numerical simulations. The involvements of the beam emittance and, mainly, the space charge effect to degrade the RFEA's efficiency have been simulated. The simulations showed that the developed RFEA, with its improved optics system and for optimum voltages on the focusing cylinder, may lead to high efficiency energy resolutions not exceeding 0.57 eV for beam energy going up to 20 keV . Acceptable errors on the measured energy spread not exceeding 30 % are, likewise, achieved despite the presence of degradations stemming from the previous degrading effects. The measurement of the average energy showed large shifts of some hundred eV from the theoretical average beam energy due to the overlapping of the ensemble of beamlets forming the HCI beam. The 3D design of this analyzer and its components will be also presented. The material of these components and their positioning to avoid electrical breakdowns will be also discussed.

Antenna Design and Prelaunch Performance of a Low-Cost 118.75 GHz Temperature Sounding CubeSat Radiometer With 3-D-Printed Corrugated Feed and Offset Reflector Optics

This article describes the design and prelaunch performance of the antenna subsystem of the low-cost 118.75 GHz temperature sounding radiometer payload used in the PolarCube and GEMS-IOD 3U CubeSat missions. Radiometric sounding measurements used for providing data for weather prediction are strongly affected by the main beam, ohmic, and spillover efficiencies of the optics, as well as by inhomogeneities in the scene and background radiation fields. The interpretation of radiometric data is affected by the accuracy with which these antenna efficiencies can be determined, particularly for radiometers that do not permit full main beam external calibration. To this end, an HE11 mode full wave Fourier–Bessel electromagnetic field analysis was developed for determination of an optimal feed horn and reflector geometry such that the main beam and spillover efficiencies of the system are maximized, and these and the antenna phase center location that maximizes phase efficiency are precisely known. The efficacy of employing a sub-millimeter wave 3-D-printed corrugated conical horn operable between 110 and 127 GHz as the feed for an offset paraboloidal reflector due to its very low cost and rapid manufacturability is also addressed. Horn measurements indicate a reflection coefficient below −15 dB and far-field radiation patterns that compare closely to simulation. Although there is some asymmetry in the horn pattern, the average main beam efficiency is 89% for a main reflector subtending a 16° half-angle. Initial performance obtained from airborne measurements over Antarctica on the NASA DC-8 during Operation IceBridge in Oct–Nov 2016 suggests a well-focused scanning antenna subsystem. After final payload assembly, the antenna’s 3 dB beamwidth extracted from a bridge-scan field experiment was broader by ~ 0.1° compared with the idealized simulated pattern.

Performance Analysis of Scheffler Solar Concentrator for Turmeric Blanching

Blanching is an important stage of post harvesting processing of turmeric, which destroys the viability of the fresh rhizomes and eliminates the raw odor. Large amount of crop residue and wood is consumed during conventional turmeric boiling process. Solar-based turmeric blanching system had been developed to show the viability of concentrated solar power for agricultural produce processing and contribute to CO2 mitigation. Experiments were conducted for several days in the month of April 2019, to study the performance of 16-m2 Scheffler concentrator for turmeric blanching. Turmeric was blanched in batches of 10 kg. Average 110 kg turmeric was successfully processed in a day. From the experimental data analysis, it is perceived that the thermal performance of the system directly depends on beam radiation. Average efficiency of 19.35 % was achieved with average beam radiation 721 W/m2. Minimum blanching time was found as 27 minutes with an average steam flow rate 5.30 kg/hr. Power available at reflector, receiver, and blanching vessel is presented to identify energy losses at each component of blanching system.

Imposing strong correlated energy spread on relativistic bunches with transverse deflecting cavities

We demonstrate a novel scheme for imposing or removing large energy chirp on relativistic electron bunches. This method relies on the transverse-to-longitudinal mixing accomplished with a set of transverse deflecting cavities. The working principles of the new concept are explained using the first-order matrix formalism in the approximation of the linear single-particle dynamics. The scheme demonstrates versatility regarding the average beam energy and, hence, positioning along the accelerator beam line. The performance of the scheme is numerically investigated with the elegant particle-tracking code. It is shown that the associated nonlinear effects causing emittance deterioration for the extreme quantities of the total energy spread can be effectively compensated by optimization of the Twiss parameters while relying on the eigenemittance analysis. The impact of the longitudinal space charge effects on the beam dynamics in the proposed scheme is also investigated.

First demonstration of a cryocooler conduction cooled superconducting radiofrequency cavity operating at practical cw accelerating gradients

We demonstrate practical accelerating gradients on a superconducting radiofrequency (SRF) accelerator cavity with cryocooler conduction cooling, a cooling technique that does not involve the complexities of the conventional liquid helium bath. A design is first presented that enables conduction cooling an elliptical-cell SRF cavity. Implementing this design, a single cell 650 MHz Nb3Sn cavity coupled using high purity aluminum thermal links to a 4 K pulse tube cryocooler generated accelerating gradients up to 6.6 MV m−1 at 100% duty cycle. The experiments were carried out with the cavity-cryocooler assembly in a simple vacuum vessel, completely free of circulating liquid cryogens. We anticipate that this cryocooling technique will make the SRF technology accessible to interested accelerator researchers who lack access to full-stack helium cryogenic systems. Furthermore, the technique can lead to SRF based compact sources of high average power electron beams for environmental protection and industrial applications. A concept of such an SRF compact accelerator is presented.

A simple, yet novel hybrid-dynamic conformal arc therapy planning via flattening filter-free beam for lung stereotactic body radiotherapy.

PurposeDue to multiple beamlets in the delivery of highly modulated volumetric arc therapy (VMAT) plans, dose delivery uncertainties associated with small‐field dosimetry and interplay effects can be concerns in the treatment of mobile lung lesions using a single‐dose of stereotactic body radiotherapy (SBRT). Herein, we describe and compare a simple, yet clinically useful, hybrid 3D‐dynamic conformal arc (h‐DCA) planning technique using flattening filter‐free (FFF) beams to minimize these effects.Materials and MethodsFifteen consecutive solitary early‐stage I‐II non‐small‐cell lung cancer (NSCLC) patients who underwent a single‐dose of 30 Gy using 3–6 non‐coplanar VMAT arcs with 6X‐FFF beams in our clinic. These patients’ plans were re‐planned using a non‐coplanar hybrid technique with 2–3 differentially‐weighted partial dynamic conformal arcs (DCA) plus 4–6 static beams. About 60–70% of the total beam weight was given to the DCA and the rest was distributed among the static beams to maximize the tumor coverage and spare the organs‐at‐risk (OAR). The clinical VMAT and h‐DCA plans were compared via RTOG‐0915 protocol for conformity and dose to OAR. Additionally, delivery efficiency, accuracy, and overall h‐DCA planning time were recorded.ResultsAll plans met RTOG‐0915 requirements. Comparison with clinical VMAT plans h‐DAC gave better target coverage with a higher dose to the tumor and exhibited statistically insignificance differences in gradient index, D2cm, gradient distance and OAR doses with the exception of maximal dose to skin (P = 0.015). For h‐DCA plans, higher values of tumor heterogeneity and tumor maximum, minimum and mean doses were observed and were 10%, 2.8, 1.0, and 2.0 Gy, on average, respectively, compared to the clinical VMAT plans. Average beam on time was reduced by a factor of 1.51. Overall treatment planning time for h‐DCA was about an hour.ConclusionDue to no beam modulation through the target, h‐DCA plans avoid small‐field dosimetry and MLC interplay effects and resulting in enhanced target coverage by improving tumor dose (characteristic of FFF‐beam). The h‐DCA simplifies treatment planning and beam on time significantly compared to clinical VMAT plans. Additionally, h‐DCA allows for the real time target verification and eliminates patient‐specific VMAT quality assurance; potentially offering cost‐effective, same or next day SBRT treatments. Moreover, this technique can be easily adopted to other disease sites and small clinics with less extensive physics or machine support.

Thermionic microwave gun for terahertz and synchrotron light sources.

Conventional thermionic microwave and radio frequency (RF) guns can offer high average beam current, which is important for synchrotron light and terahertz (THz) radiation source facilities, as well as for industrial applications. For example, the Advanced Photon Source at Argonne National Laboratory is a national synchrotron-radiation light source research facility that utilizes thermionic RF guns. However, these existing thermionic guns are bulky, difficult to handle and install, easily detuned, very sensitive to thermal expansion, and due for a major upgrade and replacement. In this paper, we present the design of a new, more stable, and reliable gun with optimized electromagnetic performance, improved thermal engineering, and a more robust cathode mounting technique, which is a critical step to improve the performance of existing and future light sources, industrial accelerators, and electron beam-driven THz sources. We will also present a fabricated gun prototype and show results of high-power and beam tests.

Wavefront preserving and high efficiency diamond grating beam splitter for x-ray free electron laser.

X-ray free electron lasers (XFELs) provide femtosecond high-power x-ray beams with high spatial coherence, resulting in numerous influential discoveries. Diffractive optics allow for the easy manipulation and measurement of an x-ray beam's wavefront and enable the realization of complex designed properties and specifications. For example, phase gratings can be used as x-ray beam splitters to enable beam sharing by multiple end stations or in-situ beam monitoring, including spectrum and wavefront measurements. Wavefront preservation and high efficiency and survivability under high power are requirements for such beam splitters. Diamond is the most suitable choice for phase grating fabrication, due to its high thermal conductivity that enables it to survive high average power XFEL beams. We have fabricated a large area (2×2 mm2) high aspect ratio (13:1) diamond grating on a diamond plate. Testing was performed at 9.5 keV and resulted in a high splitting efficiency (30%). Tunable efficiency was obtained via tilting the grating with respect to the x-ray beam. Wavefront fidelity of the split beams were measured to less than λ/100 using a Talbot wavefront sensor.

Measurement of the weak mixing angle at a Super Charm-Tau factory with data-driven monitoring of the average electron beam polarization

A method for measuring the average longitudinal polarization of the electron beam at an electron-positron collider operating near the J/ψ resonance is proposed. The method utilizes the differential cross-section of J/psi to left[Lambda to p{pi}^{-}right]left[Lambda to overline{p}{pi}^{+}right] decay. It can be used to measure the average longitudinal polarization of electrons with the statistical precision better than 10−3 at a Super Charm-Tau factory operating at the luminosity of 1035 cm−2s−1. The method is discussed in the context of the weak mixing angle measurement in the same experiment.

52 kW CW proton beam production by CYCIAE-100 and general design of high average power circular accelerator

At CIAE, we have been engaged in the development of isochronous accelerator for 60 years. From Cyclotron in the past to CW FFAG at present, isochronous accelerators have the technical advantages of high average beam intensity, fixed magnetic field and RF frequency, and low construction and operation costs. Therefore, the isochronous accelerator has been widely used. In this paper, a 100 MeV compact isochronous cyclotron CYCIAE-100 developed at CIAE in recent years is introduced. The successful commissioning of the cyclotron obtains a proton beam power up to 52 kW. Its stable operation provides dual-beam with the intensity ranges from 10 pA to 520 μA, and its applications are carried out annually for more than 30 users in different research fields. This paper also introduces a 2 GeV CW FFAG first proposed by CIAE. From the design of the 2 GeV CW machine, the energy limitation of the isochronous accelerator is increased from ∼1 GeV to 2 GeV, by our contribution of the beam dynamics study for high energy isochronous FFAG. The basic design of the key components, including HTS magnet, HP RF system, injection and extraction system, have also been explored. The preliminary conclusions suitable for engineering implementation are also presented.

A novel, yet simple MLC-based 3D-crossfire technique for spatially fractionated GRID therapy treatment of deep-seated bulky tumors.

PurposeTreating deep‐seated bulky tumors with traditional single‐field Cerrobend GRID‐blocks has many limitations such as suboptimal target coverage and excessive skin toxicity. Heavy traditional GRID‐blocks are a concern for patient safety at various gantry‐angles and dosimetric detail is not always available without a GRID template in user’s treatment planning system. Herein, we propose a simple, yet clinically useful multileaf collimator (MLC)‐based three‐dimensional (3D)‐crossfire technique to provide sufficient target coverage, reduce skin dose, and potentially escalate tumor dose to deep‐seated bulky tumors.Materials/methodsThirteen patients (multiple sites) who underwent conventional single‐field cerrobend GRID‐block therapy (maximum, 15 Gy in 1 fraction) were re‐planned using an MLC‐based 3D‐crossfire method. Gross tumor volume (GTV) was used to generate a lattice pattern of 10 mm diameter and 20 mm center‐to‐center mimicking conventional GRID‐block using an in‐house MATLAB program. For the same prescription, MLC‐based 3D‐crossfire grid plans were generated using 6‐gantry positions (clockwise) at 60° spacing (210°, 270°, 330°, 30°, 90°, 150°, therefore, each gantry angle associated with a complement angle at 180° apart) with differentially‐weighted 6 or 18 MV beams in Eclipse. For each gantry, standard Millenium120 (Varian) 5 mm MLC leaves were fit to the grid‐pattern with 90° collimator rotation, so that the tunneling dose distribution was achieved. Acuros‐based dose was calculated for heterogeneity corrections. Dosimetric parameters evaluated include: mean GTV dose, GTV dose heterogeneities (peak‐to‐valley dose ratio, PVDR), skin dose and dose to other adjacent critical structures. Additionally, planning time and delivery efficiency was recorded. With 3D‐MLC, dose escalation up to 23 Gy was simulated for all patient's plans.ResultsAll 3D‐MLC crossfire GRID plans exhibited excellent target coverage with mean GTV dose of 13.4 ± 0.5 Gy (range: 12.43–14.24 Gy) and mean PVDR of 2.0 ± 0.3 (range: 1.7–2.4). Maximal and dose to 5 cc of skin were 9.7 ± 2.7 Gy (range: 5.4–14.0 Gy) and 6.3 ± 1.8 Gy (range: 4.1–11.1 Gy), on average respectively. Three‐dimensional‐MLC treatment planning time was about an hour or less. Compared to traditional GRID‐block, average beam on time was 20% less, while providing similar overall treatment time. With 3D‐MLC plans, tumor dose can be escalated up to 23 Gy while respecting skin dose tolerances.ConclusionThe simple MLC‐based 3D‐crossfire GRID‐therapy technique resulted in enhanced target coverage for de‐bulking deep‐seated bulky tumors, reduced skin toxicity and spare adjacent critical structures. This simple MLC‐based approach can be easily adopted by any radiotherapy center. It provides detailed dosimetry and a safe and effective treatment by eliminating the heavy physical GRID‐block and could potentially provide same day treatment. Prospective clinical trial with higher tumor‐dose to bulky deep‐seated tumors is anticipated.

The GBT Diffuse Ionized Gas Survey: Tracing the Diffuse Ionized Gas around the Giant Hii Region W43

Abstract The Green Bank Telescope Diffuse Ionized Gas Survey (GDIGS) is a fully sampled radio recombination line (RRL) survey of the inner Galaxy at C-band (4–8 GHz). We average together ∼15 Hnα RRLs within the receiver bandpass to improve the spectral signal-to-noise ratio. The average beam size for the RRL observations at these frequencies is ∼2′. We grid these data to have spatial and velocity spacings of 30″ and 0.5 , respectively. Here we discuss the first RRL data from GDIGS: a 6 deg2 area surrounding the Galactic H II region complex W43. We attempt to create a map devoid of emission from discrete H II regions and detect RRL emission from the diffuse ionized gas (DIG) across nearly the entire mapped area. We estimate the intensity of the DIG emission by a simple empirical model, taking only the H II region locations, angular sizes, and RRL intensities into account. The DIG emission is predominantly found at two distinct velocities: ∼40 and ∼100 . While the 100 component is associated with W43 at a distance of ∼6 kpc, the origin of the 40 component is less clear. Since the distribution of the 40 emission cannot be adequately explained by ionizing sources at the same velocity, we hypothesize that the plasma at the two velocity components is interacting, placing the 40 DIG at a similar distance as the 100 emission. We find a correlation between dust temperature and integrated RRL intensity, suggesting that the same radiation field that heats the dust also maintains the ionization of the DIG.

Wide beam steering by slow-light waveguide gratings and a prism lens

A lattice-shifted photonic crystal waveguide (LSPCW) maintains slow light as a guided mode and works as an optical antenna when a kind of double periodicity is introduced. Selecting one LSPCW from its array and converting the fan beam to a spot beam using a collimator lens allows non-mechanical, two-dimensional beam steering. We employed a shallow-etched grating into the LSPCW as the double periodicity to increase the upward emission efficiency and designed a bespoke prism lens to convert the steering angle in a desired direction while maintaining the collimation condition for the steered beam. As a result, a sharp spot beam with an average beam divergence of 0.15° was steered in the range of40∘×4.4∘without precise adjustment of the lens position. The number of resolution points obtained was 4256. This method did not require complicated and power-consuming optical phase control like that in optical phased arrays, so it is expected to be applied in complete solid-state light detection and ranging.