High-performance phase camera as a frequency selective laser wavefront sensor for gravitational wave detectors

Kazuhiro Agatsuma*, Laura van der Schaaf, Martin Van Beuzekom, David Rabeling, Jo van Den Brand

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


We have designed, built and tested a high-performance phase camera, which can observe laser wavefronts in a large range of sideband frequencies. Our phase camera scans the laser beam over a pinhole diode and uses a heterodyne technique to independently assess the information in the upper and lower sidebands of up to five different modulation frequencies. Amplitude and phase images, consisting of 214 points each, are obtained every second for each of the 11 demodulated frequencies in parallel. The achieved sensitivity is about 4 × 10−3 rad (λ/1600 at λ = 1064 nm) at the center of the beam, corresponding to a wavefront deformation of 0.7 nm, and drops to about 3 nm over the beam size. This sensitivity is extremely useful for diagnostic purposes in gravitational wave detectors and fits the requirements for control loops in Advanced Virgo. We report on the design, realization and performance of our phase camera.

Original languageEnglish
Pages (from-to)18533-18548
Number of pages16
JournalOptics Express
Issue number13
Publication statusPublished - 1 Jan 2019


Netherlands Organization for Scientific Research (NWO) (”First direct detection of gravitational waves with Advanced Virgo (VIRGO)” project number 162). We thank Mesfin Gebyehu for developing the FPGA firmware. We are very grateful to Dr. Bas Swinkels for the many discussions on the Virgo site. The authors also thank Guido Visser and Hans Verkooijen for their contributions to the phase camera electronics. We thank the current affiliation of K. A. (School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham) for supporting him to complete this paper.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek


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