Open AccessHigh-performance phase camera as a frequency selective laser wavefront sensor for gravitational wave detectors
Author(s) -
K. Agatsuma,
L. van der Schaaf,
M. van Beuzekom,
D. S. Rabeling,
J. van den Brand
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.018533
Subject(s) - optics , wavefront , physics , detector , wavefront sensor , laser , heterodyne (poetry) , gravitational wave , heterodyne detection , phase (matter) , phase modulation , sideband , sensitivity (control systems) , acoustics , phase noise , quantum mechanics , microwave , astrophysics , electronic engineering , engineering
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 2 14 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.