We report on the first experimental demonstration of higher-order Laguerre-Gauss (LG(p)(ℓ)) mode generation and interferometry using a method scalable to the requirements of gravitational wave (GW) ...detection. GW detectors which use higher-order LG(p)(ℓ) modes will be less susceptible to mirror thermal noise, which is expected to limit the sensitivity of all currently planned terrestrial detectors. We used a diffractive optic and a mode-cleaner cavity to convert a fundamental LG(0)(0) Gaussian beam into an LG(3)(3) mode with a purity of 98%. The ratio between the power of the LG(0)(0) mode of our laser and the power of the LG(3)(3) transmitted by the cavity was 36%. By measuring the transmission of our setup using the LG(0)(0), we inferred that the conversion efficiency specific to the LG(3)(3) mode was 49%. We illuminated a Michelson interferometer with the LG(3)(3) beam and achieved a visibility of 97%.
The LISA project is a space mission that aim at detecting gravitational waves in space. An electro-optical simulator called LISA On Table (LOT) is being developed at APC in order to test noise ...reduction techniques (such as Timed Delayed Interferometry) and instruments that will be used. This document presents its latest results: TimeDelayed Interferometry of 1st generation works in the case of a simulated white noise with static, unequal arms. Future and ongoing developments of the experiment are also addressed.
This paper describes the progress on a hardware simulator of eLISA developed at the APC laboratory in Paris, France. It is designed to simulate realistic noise and the appropriate delays resulting ...from the huge distances the laser has to travel between the eLISA spacecrafts. We present the experimental setup consisting of an optical and electric interferometer. Also, the time delay interferometry noise reduction method and its performance on simulated signals in the simplest transponder case will be described.
Abstract Ophthalmologic manifestations occur in various inborn errors of metabolism (IEM), including small molecule disorders and organelle disorders. In a minority of diseases the occurrence of eye ...abnormalities could be attributed to direct toxic mechanisms of abnormal metabolic products or accumulation of normal metabolites by errors of synthetic pathways or by deficient energy metabolism. The age of onset of ocular abnormalities in IEM is variable, but onset often begins from birth to childhood. The major IEM associated with eye abnormalities include errors of lipid metabolism, carbohydrate metabolism, protein metabolism, and metal metabolism. IEM disorders with ocular motor manifestations include lipid storage diseases, neurotransmitter disorders and respiratory chain disorders. The purpose of this article is to describe ocular phenotypes associated with IEM, focusing on those diseases in which the ocular involvement is seen relatively early in the course of the disease. As therapeutic approaches become available for certain groups of IEM, the need for early diagnosis is increasingly important.
One of the main noise sources for future interferometric gravitational wave detectors will be the thermal fluctuations of the mirrors used as test masses. To reduce the effect of this noise without ...changing the mirror material, size and temperature, the use of Laguerre-Gauss (LG) modes has been proposed. In this work we report the first experimental results obtained with a Fabry-Perot Michelson interferometer operated with Laguerre-Gauss LG sub(33) as input mode and developed as a table-top prototype to test alignment and matching procedures, possible control issues and optical performances of the LG sub(33). Among the results obtained, we have demonstrated the degradation of the interferometer contrast of the LG sub(33) with respect to the Gaussian beam, predicted by several previous simulations works and due to the degeneracy of LG modes having the same order. In addition, the observed contrast degradation for the LG sub(33) as well as the interferometer optical properties have been explained using a numerical simulation.
The detection and measurement of gravitational-waves from coalescing neutron-star binary systems is an important science goal for groundbased gravitational-wave detectors. In addition to emitting ...gravitational-waves at frequencies that span the most sensitive bands of the LIGO and Virgo detectors, these sources are also amongst the most likely to produce an electromagnetic counterpart to the gravitational-wave emission. A joint detection of the gravitational-wave and electromagnetic signals would provide a powerful new probe for astronomy. During the period between Sep 19 and Oct 20, 2010, the first low-latency search for gravitational-waves from binary inspirals in LIGO and Virgo data was conducted. Over the course of the science run, three gravitational-wave triggers passed all of the low-latency selection cuts. Of these, one was followed up by several of our observational partners. Analysis of the gravitational-wave data leads to an estimated false alarm rate of once every 6.4 days, falling far short of the requirement for a detection based solely on gravitational-wave data.
The Virgo experiment, located near Pisa, Italy, is a large laser Michelson interferometer aiming at the first direct detection of gravitational waves. The interferometer monitors the relative ...distance of its mirrors placed at the ends of two 3 km-long perpendicular arms. The goal is to measure spectral differential variations of the arm lengths of 10−18 m/Hz1/2 in the frequency range from 10 Hz to 10 kHz. Avoiding spurious motions of the optical components is therefore essential to detect gravitational waves. Since the ground motion is 9 orders of magnitude larger than the arm length variations induced by gravitational waves, the seismic noise is the dominant low frequency noise source for terrestrial gravitational wave interferometers. The seismic isolation is obtained suspending the mirrors by an 8-meter tall chain of cascaded mechanical filters, called “Superattenuator” (SA). The Superattenuator is a passive device acting as a low pass filter in all six degrees of freedom, capable of attenuating the ground motion by more than 10 orders of magnitude, starting from a few Hz. To further reduce the seismic disturbances, the filter chain is suspended from an actively stabilized platform that compensates for low frequency and large amplitude oscillations caused by the mechanical resonances of the chain. In this article we describe the Superattenuator together with its control system, and we report about its performance.
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