Showing papers on "Flattop published in 2017"

Axicon-based Bessel beams for flat-field illumination in total internal reflection fluorescence microscopy

Abstract: Total internal reflection fluorescence microscopy (TIRF-M) provides low-invasive high-contrast surface imaging with optical sectioning of typically 100–200 nm. Thus, TIRF-M has become an established tool for imaging surfaces, including cell membranes. For TIRF-M, a homogenous evanescent field of excitation over the whole field of view is generally desired for quantitative microscopy; however, this is not necessarily straightforward to generate with Gaussian beams. In recent years, several improvements on TIRF-M have been developed that have addressed non-uniform scattering fringes and other artifacts. Here, we introduce a cost-effective TIRF setup with a very low degree of complexity and no moving parts, which provides a flattop-like excitation profile. The setup uses a tunable laser ring zoom focus system to generate a full 360° TIRF illumination. Two axicon lenses and one focus lens allow for generation and control of the ring diameter to tune the TIRF excitation angle. We show that 360° laser illumination in combination with a radial polarizer will generate an evanescent Bessel-beam excitation field that exhibits a flattop intensity over an extended part of the field of view, and demonstrate the advantages of this axicon-based Bessel beam illumination for live-cell imaging.

Quasi-ideal dynamics of vortex solitons embedded in flattop nonlinear Bessel beams.

Abstract: The applications of vortex solitons are severely limited by the diffraction and self-defocusing spreading of the background beam where they are nested. Nonlinear Bessel beams in self-defocusing media are nondiffracting, flattop beams where the nested vortex solitons can survive for propagation distances that are one order of magnitude larger than in the Gaussian or super-Gaussian beams. The dynamics of the vortex solitons is studied numerically and found to approach that in the ideal, uniform background, preventing vortex spiraling and decay, which eases vortex steering for applications.

Charge production studies from Cs2Te photocathodes in a normal conducting RF gun

Abstract: This work discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency gun from Cs 2 Te photocathodes illuminated with ps-long UV laser pulses and presumed homogeneous flattop laser transverse distribution. The measured charge shows the expected linear dependence in the quantum efficiency limited emission regime at low laser pulse energies. At higher laser pulse energy, the measured charge in the space charge limited emission regime should saturate, assuming an ideal homogeneous flattop laser transverse distribution. However, this behavior is not observed experimentally. Instead of saturating, the measured charge continues to increase with laser pulse energy, albeit with much weaker dependence than in the quantum efficiency limited emission regime. Simulations with the space charge particle tracking code ASTRA show that the charge saturates as expected using a homogeneous flattop laser transverse distribution. The discrepancy between simulations and measured excess charge may be attributed to the presence of unintentional Gaussian-like decaying radial halo beyond the core of the otherwise presumed homogeneous flattop core. The rate of increase of the measured charge at high laser pulse energies seems to be proportional to the amount of halo despite charge saturation in the core of the transverse laser radial profile. By utilizing core + halo particle distributions based on measured radial laser profiles, ASTRA simulations and semi-analytical emission models reproduce the behavior of the measured charge for a wide range of RF gun and laser operational parameters within the measurement uncertainties.

Resonance Control for Narrow Bandwidth PIP-II Cavities

Abstract: The PIP-II project at FNAL calls for a SRF pulsed proton driver linac to support the expanding neutrino physics program including DUNE/LBNF. The relatively low beam current and high quality factors called for in the design means that these cavities will be operated with small RF bandwidths, meaning that they will be sensitive to microphonics. Combined with a 20 Hz pulsed operational structure and the use of four different, complex cavity geometries means that resonance control will be extremely challenging. Work is ongoing at FNAL to develop active resonance stabilization techniques using fast piezoelectric tuners in support of PIP-II. These techniques as well as testing and development results using a prototype, dressed low-beta single-spoke cavity will be presented along with an outlook for future efforts. PIP-II PROTOTYPE CAVITY An extensive design and prototyping effort at Fermilab has been focused on a 325 MHz single spoke resonator for the PIP-II project. The cavity has been optimized for performance, multipacting minimization, and pressure sensitivity. Integrated tests have demonstrated functionality of the dressed cavity with tuner and highpower coupler. Figure 1: Dressed Single Spoke Resonator with tuner and high-power coupler installed in the Spoke Test Cryostat at Fermilab. This resonator is designed to operate at 2 K. PIP-II calls for a pulse structure with a 0.5 ms flattop at 12.5 MV/m, 20 Hz repetition rate, and 15% duty cycle. The coupler is designed for operation over several kW with a half bandwidth of 30 Hz. Tuning is accomplished via a single lever tuner attached to the helium vessel, acting on one beam pipe [1]. The motor is actuated via a slow motor for course tuning over large range and two piezo tuners encapsulated in such a way to act together, but still remain functional is one piezo fails. After installation in the Spoke Test Cryostat (STC) seen in Figure 1 and cooldown, the tuner is designed and set to remain barely out of contact with the cavity. The slow motor moved the tuner into contact with the cavity and preload the piezo and tuner. For the following testing, the tuner was loaded and left at the low loading end of the operating tuning range. The prototype coupler gave an initial half bandwidth of 142 Hz (Loaded Q of 1.15e6). An RF reflector was installed to narrow the cavity bandwidth, giving a final Loaded Q of 5.24e6 (31 Hz half bandwidth). RF DEVELOPMENT CIRCUIT Development was done on an FPGA based digital RF system (seen in Figure 2). Direct RF signals are downconverted to 13 MHz via narrowband, analog downconverter. These signals are then digitized at the eighth harmonic, 104 MHz, by 14-bit ADCs. Figure 2: Analog downconverter, RF transceiver, and FPGA-based RF controller. IF I/Q signals and piezo drive are calculated in the FPGA and generated by 14-bit DACs. IF signals are analog upconverted to RF frequency and sent to the high power amplifier. Monitoring, logging, and setting of registers is done via on-board PC controller. Piezo signal was amplified by a low-noise PiezoJena amplifier up to 150 Volts.

Pulsed High Power Klystron Modulators for ESS Linac Based on the Stacked Multi-Level Topology

Abstract: ESS has launched an internal R&D project in view of designing, prototyping and validating a klystron modulator compatible with the requirements based on a novel topology named SML (Stacked Multi-Level). This topology is modular and based on the utilization of High Frequency (HF) transformers. The topology allows for the usage of industrial standard power electronic components at the primary stage at full extent which can easily be placed and wired in a conventional electrical cabinet. It requires only few special components like HF transformers, rectifiers and filters (i.e. passive components) to be placed in an oil tank. This arrangement allows scaling up in average and pulse power to the required levels while keeping the size, cost, efficiency and reliability of the different modules under good control. Besides the very good output pulse power quality, the AC grid power quality is also remarkably high with a line current harmonic distortion below 3%, a unitary power factor and an extremely reduced line voltage flicker below 0.3%. A reduced scale modulator prototype has been built and validated experimentally.

Focus shaping of cylindrically polarized Bessel–Gaussian beam modulated by Bessel gratings by a high numerical aperture objective

Abstract: The focus-shaping technique of the cylindrically polarized Bessel–Gaussian-like beam, referred to the cylindrically polarized Bessel–Gaussian beam modulated by Bessel gratings, propagating through a high numerical-aperture lens is investigated theoretically and numerically in this paper, using the vector diffraction theory method. Results show that the intensity distribution in the focal region can be influenced considerably by: the beam topological charges (m, n), the beam parameter β and the polarization angle ϕ0. The intensity distribution in focal region can be tailored considerably by appropriately adjusting the polarization angle. Peak-centered, donut and flattop focal shapes with extended focal depth which are potentially useful in optical tweezers, material processing and laser printing can be obtained using this technique.

Generation of a sub-half-wavelength focal spot with purely transverse spin angular momentum

Abstract: We theoretically demonstrate that optical focus fields with purely transverse spin angular momentum (SAM) can be obtained when a kind of special incident fields is focused by a high numerical aperture (NA) aplanatic lens (AL). When the incident pupil fields are refracted by an AL, two transverse Cartesian components of the electric fields at the exit pupil plane do not have the same order of sinusoidal or cosinoidal components, resulting in zero longitudinal SAMs of the focal fields. An incident field satisfying above conditions is then proposed. Using the Richard–Wolf vectorial diffraction theory, the energy density and SAM density distributions of the tightly focused beam are calculated and the results clearly validate the proposed theory. In addition, a sub-half-wavelength focal spot with purely transverse SAM can be achieved and a flattop energy density distribution parallel to z-axis can be observed around the maximum energy density point.

PULSE forming networks development for a 60–380 ns pulsed power supply for 2 ka 20 mev linear induction accelerator

Abstract: The pulse forming networks (PFNs) were developed to provide a 2 kA, 20 MeV linear induction accelerator cells power supply A PFN's and high-voltage capacitors manufacturing is organized at BINP The PFN is a LC-network with nonuniform impedance made of capacitive sections with a combined paper-film dielectric filled with a castor oil in a polypropylene case A PFN's isolation is rated at 50 kV charging voltage The two types of PFNs are developed for 60 and 380 ns flattop duration They are capable of producing the pulses up to 21 kV, 10 kA with a ±05–1% flattop voltage uniformity at a complex inductive-resistive load of the accelerating cell The PFNs test results in the nominal regime are presented The PFNs life test results at a higher electrical field in the dielectric are described

Device and method for wafer laser processing

Abstract: The invention provides a device and method for wafer laser processing. The device comprises a laser unit, a beam expanding and collimating element, a phase-controlled-type silicon-based liquid crystal and a focusing element; the laser unit is used for emitting laser beams; the beam expanding and collimating element is used for beam expanding and collimating of the laser beams to form the parallel light beams; the phase-controlled-type silicon-based liquid crystal is used for conducing energy distribution modulation on the parallel light beams to form random customized multi-light-beam assemblies or conducting shape-correction treatment to form flattop light spots to be emitted to the focusing element; and the focusing element is used for emitting the random customized multi-light-beam assemblies or the flattop light spots to the upper surface of a wafer and removing Low-K materials of the upper surface of the wafer in the pre-set cutting way direction. According to the device and method for wafer laser processing, through the phase-controlled-type silicon-based liquid crystal, energy distribution modulation or shape-correction treatment is conducted on the parallel light beams to improve the work efficiency and accuracy of the processing method and the uniformity of wafer separation, and the device and method for wafer laser processing can be suitable for the requirements of the various flattop light spots.

Beam shaping by means of different wavefront correctors

Abstract: For some applications it is necessary to transform an intensity distribution from Gaussian to a flattop, doughnut, etc. It could be performed with the use of adaptive optics that distorts the phase of the beam and changes the shape of the focal spot in the far-field. In this paper, we present the flattop and doughnut beam formation result with the use of a bimorph and stacked-actuator deformable mirrors. The experimental results are also given.

JACoW : Beam-Based Kicker Waveform Measurements Using Long Bunches

Abstract: The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project [1] to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1.KFA10, BT4.KFA10 and BT2.KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness.

Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation

Abstract: Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 80 ps long bunch of electrons with charge up to 200 pC. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser subpulse length and on the relative delay between these subpulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors – the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.

Non-Linear Kickers Using Eddy Current Screens and Application to the ESRF

Abstract: The ESRF storage ring injection and accumulation is performed using standard 4-kickers bump and septum magnet. Sextupoles are located within the injection bump leading to significant bump non-closure during the ramp-up and rampdown and optics distortion for both stored and injected beam. Introducing non-linearities in the kickers allows for compensation of the perturbation from these sextupoles. We report on the feasibility of adding eddy current screens to a standard kicker magnet design to generate a non-linear field and its recent application to mitigate the injection perturbations at the ESRF.

Generation of an ultra-flexible focused top-hat beam profile with aspheres

Abstract: The demand for a uniform intensity distribution in the focal region of the working beam is growing steadily, especially in the field of laser material processing. To generate such a top-hat beam profile, it was shown in the past, that the use of refractive beam shaping solutions provides very good results. In this work, existing beam shaping knowledge is combined with an intelligent modular approach to create a new beam shaping solution, that simplifies both, handling and integration into existing set-ups. Furthermore, the present system enables not just a flattop intensity distribution, but even donut shaped beam profile without adding any further components to the system. Additionally, this beam shaping system is built and successfully tested. Some results of the characterization are presented.

Data-Driven Controller Design for High Precision Pulsed Power Converters for Bumper Magnets of the PS Booster

Abstract: A data-driven approach using the frequency response function of a system is proposed for designing robust digital controllers for the injection bumper magnet (BSW) power supplies of the PS Booster. The powering of the BSW requires high precision 3.4 kA to 6.7 kA trapezoidal current pulses with 2 ms flat-top and 5 ms ramp-up and ramp-down time. The tracking error must remain within +/50 parts-permillion (ppm) during the flat-top of the trapezoidal reference, and +/500 ppm during the ramp-down. The BSW is powered with a SIRIUS P2P power converter and the current through the magnet is controlled in closed-loop form with a 2-degree-of-freedom controller at a sampling rate of 10 kHz. A convex optimization algorithm is performed for obtaining the controller parameters. The effectiveness of the method is illustrated by designing the controller for a full-scale prototype of the BSW system at CERN, which is in the framework of the LHC Injector Upgrade (LIU) project. INTRODUCTION The data-driven control strategy mitigates the problems with model-based controller designs by avoiding the problem of unmodeled dynamics associated with low-order parametric models. A survey on the differences between the model-based control and data-driven control schemes has been addressed in [1] among many others. With the datadriven control scheme, the parametric uncertainties and the unmodeled dynamics are irrelevant and the only source of uncertainty comes from the measurement process. In this paper, the frequency-domain approach will be utilized for the controller design. Robust controller design methods belonging to the H∞ control framework minimizes the H∞ norm of a weighted closed-loop sensitivity function. In [2–5], frequency-domain approaches are proposed in order to design controllers that satisfy the H∞ condition. The work in this paper presents a method based on [5] and uses a convex optimization algorithm to compute robust RST controllers for high precision pulsed power converters. CERN adopted the RST control strategy for the control of the current in the magnets within the FGC platform [6]. The RST controller structure is indeed an effective discrete-time two-degree of freedom (2DOF) polynomial controller where the tracking and regulation characteristics of a closed-loop system can be formulated independently, which is definitely an important feature in many applications. This frequency-domain approach for the design of RST controllers is applied here to the 3.4 kA SIRIUS P2P power ∗ michele.martino@cern.ch R(z−1, ρ) N(z−1) M(z−1) T (z −1, ρ) 1 S(z−1,ρ) r

Opal Simulations of the PSI Ring Cyclotron and a Design for a Higher Order Mode Flat Top Cavity

Abstract: The PSI cyclotron has been producing high power proton beam for 42 years. Over its lifetime it has been upgraded from producing 100 μA to 2.2 mA at 590 MeV. As the power reaches higher levels, it become more important to understand how the machine’s beam dynamics will react to new devices introduced. We present an OPAL (Object Oriented Parallel Accelerator Library) model of the cyclotron and compared it to the probe measurements from the machine. This model has good agreement with the measurements over the ~180 turns in the machine. Using this same model, a higher order mode flat top cavity was inserted into the machine and the number of turns was decreased corresponding to an increase in maximum current. The HOM cavity design will also be presented. INTRODUCTION The Ring Cyclotron at the Paul Scherrer Institut accelerates 2.2 mA of proton beam from 71 MeV to 590 MeV. This was accomplished by progressively upgrading components, such as the four Main RF cavities that were redesigned to increase the accelerating voltage from 730 kV to 1 MV [1,2]. Currently the limiting feature in the cyclotron is the Flat Top Cavity. This cavity operates in the 3rd harmonic and increases the longitudinal acceptance of the machine. The cavity has reached its voltage limit due an inability to keep the cavity tuned caused by deformation from heating, as well as other associated problems [3,4]. A new Flat Top cavity was designed to allow for higher voltages which would ultimately lead to higher currents in the Ring. However, to show that the cavity would work as anticipated, a model of the cyclotron that could reproduce the existing beam and setup was needed. OPAL SIMULATIONS Prior Simulations Object Oriented Parallel Accelerator Library, OPAL, is an open source particle accelerator simulation code capable of massive parallel processing [5,6]. OPAL-CYC, one of the suite of tools in OPAL, was used for this work. OPAL was used to model the Ring cyclotron in 2011 by Bi, but the model was only matched to the experimental data for last 9 turns [7]. The result of the model, Fig. 1, showed that OPAL could match experimental data from beam profile monitors to a high degree with initial parameters consistent with those in the control room. These simulations provided stimulus to see if the entire cyclotron could be modelled, matched to experimental data, and create a platform to test new devices. Current Simulation The goal of this study was to obtain an accurate model of the entire Ring via orbit matching and phase matching for all orbits. Several additions were made to the existing model as well as a few modifications to OPAL itself. One such set of modifications was improved trim coil placement in the sector dipoles and the trim coil profiles themselves. In the previous model only trim coil 15 (TC15) was used, but all 18 trim coils were inserted and magnet profiles generated to create more realistic conditions, Fig. 2. To model the entire cyclotron, identifying the exact placement of the probes, or beam profile monitors, is of critical importance to align the modelled and experimental data. No single probe covers all the turns in the cyclotron. Therefore, three profile monitors were identified (Fig. 3) that could cover all orbits, RRI2 – the injection probe, RRL – the long probe, and RRE4 – the extraction probe. The monitors have been moved over the years, and therefore the exact positions were obtained with respect to the machine center. Finding experimental data for all three probes for the same RF settings, injection energy, and trim settings was difficult. A set was identified [8], where the probe positions were exactly known, that met these requirements and were close in proximity in time to each other. The data for RRE4 and RRI2 were from July 5th 2012 and for the RRL the data was 7 days earlier. The initial beam parameters were taken from Anna Kolano’s Injector II OPAL simulation [9]. From the injector ____________________________________________ * This work was performed using funds from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n.◦290605 (PSI-FELLOW/COFUND). This work was prepared under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. † email address: pogue1@llnl.gov # Previously at Paul Scherrer Institute Figure 1: Bi’s simulation [7] overlapped with experimental measurements for the last 9 orbits of the Ring cyclotron. Proceedings of IPAC2017, Copenhagen, Denmark THPAB077 05 Beam Dynamics and Electromagnetic Fields D11 Code Developments and Simulation Techniques ISBN 978-3-95450-182-3 3891 Co py rig ht © 20 17 CC -B Y3. 0 an d by th er es pe ct iv ea ut ho rs

An approach to realisation of a Radial Phase mask using 3-D printing in transparent PLA

Abstract: In the recent years, many different techniques and algorithms have been devised to design diffractive optical elements (DOE’s) for the purpose of beam shaping This paper demonstrates an approach to realise a 3-D printed radial phase mask to be used in beam shaping to achieve a beam profile closer to the flattop An iterative algorithm approach is employed to simulate the phase masks in greyscale and subsequently into STL format These 3-D printed masks are used as an optical element and characterised using an experimental setup The images of the light after the characterisation are examined and compared with the simulated results Therefore, this method reduces the complexity as 3-D printing the masks eliminates the need for fabrication, processing time and number of components necessary to obtain a flattop beam profile

Analysis of performance of high light-energy-utilization-ratio laser communication antenna based on axicon

Abstract: According to the transverse intensity distribution of the TEM00 Gaussian light field and character of an irradiance redistribution element, we proposed a novel method, which has the advantages of high light-energy-utilization-ratio (LEUR). The current laser communication (LASCOM) antenna frequently employs the Cassegrain reflective optical structure, in which the secondary mirror will introduce a center obscuration, leading to high ratio of transmitting power loss. To solve this problem, we make the transmitting beam pass through double convex axicons. The Gaussian peak of incident light coming into the central part of such element, will go out from near the peripheral part of the second axicon, and the edge part of Gaussian beam will go out from the central part. When the changed beam passes the Cassegrain structure, the utilizing efficiency will be raised obviously. In the paper, on different obscuration rate, the LEURs of LASCOM system before and after using the axicons are compared. In addition, the far-field intensity distribution of the laser beam changed by the axicon pair and transmitted by the antenna is calculated. The simulation result shows that the LEURs of antenna with and without an axicon pair are 91.7% and 28.9% on a Line obscuration ratio of 1/4. After a propagation of 1000 km, the far-field energy distribution of the hollow beam translated by the high LEUR antenna is closer to a flattop beam than that for the common Gaussian beam.

Development of a 100 kV pulse generator for driving an electron scanner used in proton beam profile measurements

Abstract: The Spallation Neutron Source (SNS) utilizes an electron scanner in the accumulator ring for nondestructive transverse profiling of the proton beam The electron scanner consists of a high voltage pulse generator driving an electron gun, a medium voltage ramp generator, and a CCD camera A new high voltage pulse generator that provides negative 100 kV pulses with rise times of less than 200 ns, +/−05% flattop of greater than 100 ns has been designed, delivered, and undergone extensive testing The pulse generator has been operationally verified with the existing control system and simulated loads Full system testing with the actual electron scanner is planned This paper details the requirements, design, setup, and test results of the high voltage pulse generator

Suppression of RF Radiation Originating from the Flattop Cavity in the PSI Ring Cyclotron

Abstract: In the PSI Ring cyclotron, protons are accelerated from 72 MeV to 590 MeV. In several upgrade programs, the beam current was increased from the initial design value of 100 μA up to 2.4 mA. The rf-system of this separated sector cyclotron consists of 4 copper cavities running at 50 MHz for the main acceleration. For the purpose of increasing the phase acceptance of the Ring, an aluminum flattop cavity is operated at a gap voltage of 555 kVp at the 3rd harmonic frequency. As a result of the progressively increased flattop voltage, this cavity was pushed toward its mechanical and electrical limits. As a consequence, rf-power is leaking into the cyclotron's vacuum space and is causing several problems. A visible effect was the formation of plasma in the vacuum chamber [1]. In the last shutdown, an attempt was made to reduce the radiated rf-power. On the vacuum sealing between the flattop cavity and sector magnet 6, a shim was installed which reduces the gap for the beam from 60 mm to 25 mm in height. Results of this intervention will be presented and compared with finite element model simulations.

Switching Magnet for Heavy-Ion Beam Separation

Abstract: We present a design for a complete switching magnet system capable of deflecting 8-25 MeV/u heavy-ion beams by 10 degrees. The system can produce flat-top pulses from 1 to 30 ms with rise and fall times of less than 0.5 ms at a duty cycle of 3-91% into a heavily inductive load. As determined by physics needs, the operational parameters of this magnet place it between fast rising kicker magnets with short duration and slow rising (or DC) resistive magnets which are optimized for efficiency and current-based power loss. This magnet must operate efficiently with over 91% duty factor and have a modestly fast rise time. The resulting design uses a resistive magnet scheme, to optimize the current-based losses, that is pulsed using a new circuit to control the applied voltage. The magnet has a laminated, iron dominated, H-shaped core. Directly-cooled copper pancake coils energize the magnet. The modulator employs a novel, proprietary, over-voltage topology to overcome the inherent inductance and achieve the fast rise and fall times, switching to a precision DC supply to efficiently maintain the flattop without requiring voltage in excess of ±3 kV.

Optical beam shaping design through optimization of a radial phase mask

Abstract: Laser beams shaped into flattop are widely used in various industrial and medical applications. There are various approaches to produce a flattop beam from a Gaussian beam. In this paper, a novel approach called Method of Projection is used to optimize a single element Radial phase mask to obtain flattop output beam. In this approach, Henkel transform and cross-correlation in iterative loop is used to optimize the parameters. Following this approach, a suitable phase mask pattern is obtained in grayscale. The simulated results are compared with target intensity profile through cross-correlation and further optimized to reach certain goodness value. The designed algorithm is a single element radially symmetric phase mask, which is low cost, alignment-free and robust. Hence, the proposed approach reduces the number of components required to develop a flattop output.