Conveners
Scattered light workshop: Hour 1
- Andreas Freise
- Alena Ananyeva (Caltech)
Scattered light workshop: Hour 2
- Andreas Freise
- Alena Ananyeva (Caltech)
Scattered light workshop: Hour 3-4
- Andreas Freise
- Alena Ananyeva (Caltech)
In this talk we present a summary of the mitigation strategies followed up in the current LIGO/Virgo experimental setups, together with the related studies carried out to determine the residual noise budget, potentially affecting the GW signals. We conclude with some indications of potential improvements in preparation for 3rd generation experiments.
As part of the upgrade program, Virgo has just installed a new baffle equipped with photosensors that surrounds the end-mirror of the input mode-cleaner. This culminates more than two years of work at IFAE-Barcelona for the design and construction of a novel and innovative device to control and monitor stray light inside the experiment, a persistent source of noise in interferometers. It will...
We here discuss our preliminary findings regarding laser microsctructuring and high-absorption coatings as a potential choice for surface treatments in gravitational wave telescopes for scattered light reduction.
The problem of back-scattered light is a major issue at low frequencies and must be tackled to make ET sensitive down to 2 Hz. Back-scatter arises as DC light, either by well-defined light paths due to the design of the optics, by diffraction of the tails of these light paths or imperfect surfaces of the test masses. Diverted out of the main modes and scattered back by modulated surfaces, it...
Surface roughness of optics and dust contamination are two main sources of stray light in advanced GW detectors: stray light can not only contribute extra noise if it recouples to the main beam when reflected by vibrating surfaces, but can also spoil the control signals of the interferometer.
Given the extremely low roughness of the optics employed, dust contamination is critical as it can...
Perspective of the work done during the reviews in the context of scattered light in Advanced Virgo Plus. In particular, study of ghost beams on different detector systems (frequency dependent squeezing, detection) with consequent mitigation actions performed and planned. Status of the tools available for the study of stray light in gravitational wave detectors and future research prospects to...
The Laser Interferometer Space Antenna (LISA) was selected to be the third large mission of the European Space Agency’s Cosmic Vision program. LISA, a space-based gravitational wave observatory, will detect gravitational waves in the frequency band extending from 0.1 mHz to 0.1 Hz by measuring picometer-scale length changes along the 2.5 Gm arms of a triangular constellation of satellites....
LISA is a constellation of three spacecraft exchanging laser beams on a 2.5 Mkm triangle. The GW measurement exploits heterodyne interferometric phase measurements of the distance between distant optical benches, with additional interferometers measuring the test mass to optical bench movement, and the optical phase difference of the two lasers onboard the same spacecraft. Stray light (SL) can...
A number of upgrades are planned to be installed for the LIGO 4th observation run, including a new optical path for the frequency dependent squeezer, 300m filter cavity and low loss Fadaray isolators. Any new components added close to the optical path may cause scattered light to propagate toward parts of the vacuum envelope and other components not isolated or less isolated from the...
In this talk, we will introduce several aspects of stray-light control in the KAGRA interferometer. The stray light to be controlled include ghost beams and scattered light produced at optics and mechanical structures in the interferometer and recombined somehow back into the main beam path. These unwanted lights could become critical noise in the end. Although the stray-light noise can be...
The high reflective mirrors of the gravitational waves detector LIGO & Virgo present in the coating many micrometer size defects that scattered the light in the interferometer. This scattered light induces a loss of the laser power of the order of a few tens of parts per million (ppm) and a phase noise because of the recombination with the main beam after reflection on the tube walls. This...
Noise from laser backscattering and spurious beam couplings has been an important limitation in first and second generation detectors. In this talk we discuss the on-going design and experimental work for Cosmic Explorer, focusing on the modeling of light scattered by the mirror surface roughness, point defects and noise due to light scattered and diffracted/clipped by the arm cavity baffles.
For the O5 run of LIGO, it is planned to make a change to the detection scheme, operating with balanced homodyne detection. This involves the introduction of a local oscillator beam derived from the power recycling cavity, to be re-combined with the signal beam from the interferometer in the detection chamber. The layout of the detection chamber has been re-designed to accommodate dual output...
