A new instrumented baffle was installed in Spring 2021 at Virgo surrounding the suspended mirror in the input mode cleaner triangular cavity. It serves as a demonstrator of the technology designed to instrument the baffles in the main arms in the near future. We present, for the first time, results on the measured scattered light distribution inside the cavity as determined by the new device using data collected between May and July 2021, with Virgo in commissioning phase and operating with an input laser power in the cavity of 28.5 W. The sensitivity of the baffle is discussed and the data is compared to scattered light simulations.
Formation of microchannels produced through 1 mm thick photostructurable glass (Foturan®) samples with two different lasers, an IR laser that gives 450 fs pulses at 1027 nm wavelength and an UV laser delivering 10 ns pulses at 355 nm wavelength, has been studied. After laser irradiation, the samples were submitted to thermal treatment and selective etching with hydrofluoric acid (HF) for microchannel formation. Two different acid concentrations (5% and 10%) were tested. It has been found that photoexcitation with the femtosecond laser can be related to a multiphoton absorption process requiring eight photons, and the critical dose of radiation for this process to occur has been determined. Etch rates with 10% HF are about two times higher than with 5% HF under equal irradiation conditions, while similar etch contrast ratios are attained. High etch rate ratios, together with small modified areas, have been found to play a determinant role in obtaining microchannels with the best aspect ratios. Use of the femtosecond laser in the IR allows the modification of smaller zones, but to the detriment of high etch rates.
a b s t r a c tThe exclusive ability of laser radiation to be focused inside transparent materials makes lasers a unique tool to process inner parts of them unreachable with other techniques. Hence, laser direct-write can be used to create 3D structures inside bulk materials. Infrared femtosecond lasers are especially indicated for this purpose because a multiphoton process is usually required for absorption and high resolution can be attained. This work studies the modifications produced by 450 fs laser pulses at 1027 nm wavelength focused inside a photostructurable glass-ceramic (Foturan ® ) at different depths. Irradiated samples were submitted to standard thermal treatment and subsequent soaking in HF solution to form the buried microchannels and thus unveil the modified material. The voxel dimensions of modified material depend on the laser pulse energy and the depth at which the laser is focused. Spherical aberration and selffocusing phenomena are required to explain the observed results.
A novel instrumented baffle surrounding the suspended end mirror in the input mode cleaner cavity of the Virgo interferometer was installed in Spring 2021. Since then, the device has been regularly operated in the experiment, and the data collected show good stability. The baffle will operate in the upcoming O4 observation run, serving as a demonstrator of the technology designed to instrument the baffles in front of the main mirrors in time for O5. In this paper, we present a detailed description of the baffle design, including mechanics, front-end electronics, and data acquisition as well as optical and vacuum compatibility tests, calibration and installation procedures, and performance results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.