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Title: Adaptive electron beam shaping using a photoemission gun and spatial light modulator

Abstract

The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Cornell University, Ithaca, NY (United States). Cornell Laboratory for Accelerator-Based Studies and Education.
Publication Date:
Research Org.:
Cornell University, Ithaca, NY (United States). Cornell Laboratory for Accelerator-Based Studies and Education.
Sponsoring Org.:
USDOE
OSTI Identifier:
1179916
Alternate Identifier(s):
OSTI ID: 1188409
Grant/Contract Number:
SC0003965; SC00039650
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review Special Topics. Accelerators and Beams
Additional Journal Information:
Journal Volume: 18; Journal Issue: 2; Journal ID: ISSN 1098-4402
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Maxson, Jared, Lee, Hyeri, Bartnik, Adam C., Kiefer, Jacob, and Bazarov, Ivan. Adaptive electron beam shaping using a photoemission gun and spatial light modulator. United States: N. p., 2015. Web. doi:10.1103/PhysRevSTAB.18.023401.
Maxson, Jared, Lee, Hyeri, Bartnik, Adam C., Kiefer, Jacob, & Bazarov, Ivan. Adaptive electron beam shaping using a photoemission gun and spatial light modulator. United States. doi:10.1103/PhysRevSTAB.18.023401.
Maxson, Jared, Lee, Hyeri, Bartnik, Adam C., Kiefer, Jacob, and Bazarov, Ivan. Sun . "Adaptive electron beam shaping using a photoemission gun and spatial light modulator". United States. doi:10.1103/PhysRevSTAB.18.023401.
@article{osti_1179916,
title = {Adaptive electron beam shaping using a photoemission gun and spatial light modulator},
author = {Maxson, Jared and Lee, Hyeri and Bartnik, Adam C. and Kiefer, Jacob and Bazarov, Ivan},
abstractNote = {The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.},
doi = {10.1103/PhysRevSTAB.18.023401},
journal = {Physical Review Special Topics. Accelerators and Beams},
number = 2,
volume = 18,
place = {United States},
year = {Sun Feb 01 00:00:00 EST 2015},
month = {Sun Feb 01 00:00:00 EST 2015}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevSTAB.18.023401

Citation Metrics:
Cited by: 4works
Citation information provided by
Web of Science

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  • The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam imagemore » to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.« less
  • In this work we describe laser beam scanning using a ferroelectric liquid crystal spatial light modulator. Commercially available ferroelectric liquid crystal spatial light modulators are capable of displaying 85 colored images in 1 s using a time dithering technique. Each colored image, in fact, comprises 24 single bit (black and white) images displayed sequentially. We have used each single bit image to write a binary phase hologram. For a collimated laser beam incident on the hologram, one of the diffracted beams can be made to travel along a user defined direction. We have constructed a beam scanner employing the abovemore » arrangement and demonstrated its use to scan a single laser beam in a laser scanning optical sectioning microscope setup.« less
  • OAK-(B204)A phase-only spatial light modulator is used in conjunction with a spatial filter to provide independent control of the phase and amplitude of a laser beam. Continuous amplitude modulation of the beam is achieved with a resolution relevant to beam shaping of high-energy laser beams. Amplitude beam correction in a closed loop is demonstrated.
  • Atmospheric propagation results for a high-speed, large-actuator-number, adaptive optics system are presented. The system uses a MEMS-based spatial light modulator correction device with 1024 actuators. Tests over a 1.35 km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large actuator number MEMS-based spatial light modulators to replace conventional deformable mirrors.