RU2367984C1 - Gravitation-wave detector - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: invention is related to laser-interferometric gravitation-wave (GW) detectors and may be used for detection of low-frequency periodical gravitation-wave signals from binary relativistic astrophysical objects. Substance of invention consists in the fact that due to introduction of double-resonator laser system of auxiliary and end mirrors into each resonator, as well as semitransparent plate and polariser, easier performance of alignment, adjustment and spatial separation of optical resonator radiations is achieved, which results in more reliable and stable operation of GW detector laser system.

EFFECT: development of GW detector on the basis of double-resonator laser system with common active medium and geometrically non-equivalent contours.

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Description

The invention relates to laser-interferometric gravitational-wave (GW) detectors and can be used in gravitational-wave astronomy, for example, to detect periodic low-frequency gravitational-wave signals from binary astrophysical objects.

It is known that there is a theoretical prediction about the formation of the elastodynamic response of the Weber detector [1] and the electrodynamic response of long-base [1] and compact [2] laser interferometric antennas to the effect of the field of gravitational radiation (GI). Weber-type GW antennas and long-base laser interferometric antennas are designed to detect short pulsed GW signals from flash sources, the spatio-temporal characteristics of which are unknown, which reduces the reliability of their detection. The required instantaneous signal-to-noise ratio for reliable detection of the GW signal from the flash source of the GI should be greater than 13. In addition, there are GV detectors [3, 4], the principle of which is that as a result of the GV action of the detected periodic low-frequency GW signal to the optical radiation of the first and second optical resonators (both traveling and standing waves) through a change in their refractive indices along the optical propagation paths of radiation, there is an incursion of phases in optical radiation x according to the law of change of the GV signal. Due to the geometric nonequivalence of the first and second resonators, this effect leads to various changes in the refractive indices along the optical propagation paths of radiation and, consequently, to different phase incursions in these optical radiation. By the presence, magnitude and law of variation of the phase difference difference in the optical radiation of the resonators, the effect of the GW signal on the optical radiation of the resonators is judged, and therefore the presence (detection) of the detected GV signal. Thus, these devices [3, 4] have the fundamental possibility of detecting periodic low-frequency GW signals from binary relativistic astrophysical objects.

Known [5] a GW detector for detecting periodic GW signals, which is closest to the claimed object and therefore is selected as a PROTOTYPE. It is a laser with two geometrically nonequivalent first and second optical standing-wave resonators. The first resonator contains a first partially transmissive mirror, a first polarizing dividing prism, the second resonator contains a second partially transmitting mirror, a second polarizing dividing prism, both resonators having a common active element and a working medium in it. Optical radiation generated in the first and second resonators have mutually orthogonal linear polarizations. Due to the spatial and geometrical nonequivalence of the first and second PROTOTYPE resonators, the principle of operation of the latter is similar to the above-described GW detectors [3, 4].

However, as shown by experimental studies [6], the prototype has a significant drawback due to the extreme complexity of the alignment, adjustment and spatial separation after polarization separation prisms of the radiation of the first and second resonators.

The problem to which the claimed invention is directed, is to develop a gravitational-wave detector, which can greatly facilitate the alignment, tuning and spatial separation of the radiation of the first and second resonators.

The essence of the invention lies in the fact that in the known gravitational-wave detector containing the active element and the working medium in it, the first and second polarizing dividing prisms with mutually orthogonal transmission planes, the first and second partially transmitting output mirrors and a series-connected photodetector and signal processing system , which is the output of the device, to solve the problem, the first and second auxiliary mirrors, the first and second end mirrors, and also the floor are introduced into it a transparent plate and a polarizer, and the first end mirror, the first polarizing dividing prism, the first auxiliary mirror, the active medium, the second auxiliary mirror, the second polarizing dividing prism, and the first partially transmitting output mirror, sequentially placed on the path of optical radiation, form the first standing-wave optical cavity, sequentially placed on the path of optical radiation, the second end mirror, the second polarizing dividing prism, the second in an auxiliary mirror, an active medium, a first auxiliary mirror, a first polarizing dividing prism and a second partially transmitting output mirror form a second standing-wave optical resonator, and the linearly polarized optical radiation of the first resonator is reflected from the semi-transparent output of the first output mirror from the translucent plate, the linearly polarized optical radiation the second resonator, mutually orthogonal to the radiation of the first resonator from the output of the partially transmitting second about the output mirror passes through a translucent plate, and spatially combined radiation of both resonators from the output of the translucent plate, passing through the polarizer, providing their interference, are fed to the input of the photodetector.

The introduction of new elements: the first and second auxiliary mirrors, the first and second end mirrors, the translucent plate and the polarizer, as well as their relative positioning, make it possible to achieve the solution of the problem posed — to facilitate the alignment, tuning, and spatial separation of the radiation of the first and second resonators, which more reliable and stable operation of the laser system of the GV detector.

In the known technical solution, measures are complicated to ensure alignment, tuning and spatial separation of the radiation of the first and second resonators.

Thus, in the inventive GW detector based on a laser with two spatially nonequivalent resonators after the introduction of auxiliary and end mirrors, a translucent plate and a polarizer, it becomes possible to significantly facilitate the alignment, tuning and spatial separation of the radiation of the first and second resonators.

Functional diagram of the inventive device is presented in figure 1.

The active medium 1, which serves to generate laser radiation, is located between the auxiliary mirrors 4 and 5. In the direction of the optical radiation emanating from the first auxiliary mirror 4, coming from the active medium 1, there is a first polarizing dividing prism 3. In the direction of the deflected first polarizing dividing prism 3 of optical radiation reflected from the first auxiliary mirror 4, the first end mirror 2 is located. As it passed through the first polarizing dividing prism 3 o The second half-transmitting output mirror 9 is located in the direction of the optical radiation reflected from the first auxiliary mirror 4. A second polarizing dividing prism 6 is located along the direction of the optical radiation reflected from the second auxiliary mirror 5 and the second polarizing dividing prism 6 optical radiation reflected from the second auxiliary mirror 5, is the second end mirror 8. In the course of the passage through the second polarization time the first prism 6 of the optical radiation reflected from the second auxiliary mirror 5 is located the first partially transmitting output mirror 7. In the direction of the optical radiation reflected from the first auxiliary mirror 4 and passing through the first polarizing dividing prism 3 passing through the second partially transmitting output mirror 9, are located sequentially a translucent plate 10, a polarizer 11, a photodetector 12 and a signal processing unit 13.

The device operates as follows.

Optical radiation with a full set of polarizations, leaving the active medium 1, is reflected from the auxiliary mirror 4 and falls on the polarization separation prism 3. A part of the optical radiation with TE polarization is deflected by element 3 and autocollimatively reflected from the first end mirror 2, after which it is again deflected by the element 3 in the direction of the auxiliary mirror 4, is reflected from it, passes through the active medium 1 and after reflection from the auxiliary mirror 5 and passing through the polarizing prism 6 auto-collimator ion reflected from the partially transmitting output mirror 2, providing the generation of a standing wave of TE polarization in the first resonator. Another part of the radiation with TM polarization after passing through element 3 is automatically collimated from a partially transmitting output mirror 9, after which it passes through element 3 again, is reflected from auxiliary mirror 4, passes through active medium 1, is reflected from mirror 5, and is deflected by polarizing prism 6 and it is self-collimating reflected from the second end mirror 8, providing generation of a standing wave of TM polarization in the second resonator. Due to the polarization separation prisms 3 and 6, optical radiation is generated on mutually orthogonal linear polarizations in spatially nonequivalent first and second resonators. The optical lengths of the first and second resonators (arm lengths of the interferometer) are aligned in order to obtain the same generation frequency ω _{0 of} their emissions with TE and TM polarizations (work in the capture zone). Gravitational radiation in force

где h≈10^-22 - безразмерная амплитуда гравитационной волны. В результате происходит индуцированное выделяемым ГВ-сигналом периодическое изменение разности фаз между оптическими излучениями первого и второго резонаторов. Выходящие с помощью частично пропускающих зеркал 7 и 9 излучения из первого и второго резонаторов пространственно совмещаются с помощью полупрозрачной пластины 10, а после прохождения через поляризатор 11, у которого плоскость пропускания света образует угол 45° с плоскостью чертежа, на входе фотоприемника 12 создают интерференционное поле. Сигнал с фотоприемника 12 поступает в блок обработки сигналов 13, который служит для выделения полезного сигнала из шумов.The spatial nonequivalence of the first and second resonators affects their generation frequencies differently. According to the methodology for calculating the natural frequencies of the resonators in the field of gravitational radiation [3], the difference in the generation frequencies of the first and second resonators will be equal to

where h≈10 ^-22 is the dimensionless amplitude of the gravitational wave. As a result, a periodic change in the phase difference between the optical radiation of the first and second resonators induced by the emitted GW signal occurs. The radiation coming out with the help of partially transmitting mirrors 7 and 9 from the first and second resonators is spatially aligned using a translucent plate 10, and after passing through a polarizer 11, in which the light transmission plane forms an angle of 45 ° with the drawing plane, an interference field is created at the input of the photodetector 12. . The signal from the photodetector 12 enters the signal processing unit 13, which serves to isolate the useful signal from the noise.

The introduction of auxiliary mirrors 4 and 5, end mirrors 2 and 8, a translucent plate 10 and a polarizer 11, due to their relative positioning, as shown in the drawing, allows, in contrast to the PROTOTYPE, to achieve the solution of the problem - providing easier adjustment, adjustment and spatial separation of radiation of the first and second resonators.

Thus, in the inventive GW detector based on a laser with two spatially nonequivalent resonators after the introduction of auxiliary and end mirrors, a translucent plate and a polarizer, it becomes possible to significantly facilitate the alignment, tuning and spatial separation of the radiation of the first and second resonators.

Information sources

1. Milyukov V.K., Rudenko V.N. // Results of science and technology VINITI USSR Academy of Sciences, series Astronomy, 1991, v.41, p.147-193.

2. Balakin A.B., Kisunko G.V., Murzakhanov Z.G., Rusyaev N.N. // DAN of the USSR, 1991, t.316, No. 5, p.1122-1125.

3. Balakin A.V., Murzakhanov Z.G., Skochilov A.F. // Gravitation & Cosmology, 1997, Vol. 3, N1 (9), p. 71-81.

4. Balakin A.B., Kisunko G.V., Murzakhanov Z.G., Skochilov A.F. // DAN of Russia, 1998, vol. 361, No. 4, p. 477-480.

5. Daishev R.A., Murzakhanov Z.G., Skochilov A.F. // Gravitation & Cosmology, 2006, Vol. 12, N1 (45), p. 78-84.

6. Agachev AP, Belozerov AF, Buinov GN, Komissaruk VA, Lukin AV, Lyubimov AI, Mavrin SV, Murzakhanov ZG, Rafikov R. A., Skochilov A.F., Cheredilin V.A., Chugunov Yu.P. // Optical journal, 2002, t. 69, No. 12, pp. 7-13.

Claims (1)

Gravity-wave detector containing the active element and the working medium in it, the first and second polarization dividing prisms with mutually orthogonal transmission planes, the first and second partially transmitting output mirrors and a series-connected photodetector and signal processing system, which is the output of the device, characterized in that the first and second auxiliary mirrors, the first and second end mirrors, and also a translucent plate and a polarizer are introduced into it, and the first end mirror, the first polarizing dividing prism, the first auxiliary mirror, the active medium, the second auxiliary mirror, the second polarizing dividing prism, and the first partially transmitting output mirror that are partly transmitted through the optical radiation path form the first standing-wave optical resonator, and the second end mirror, second polarizing dividing prism, second auxiliary mirror, active medium, first auxiliary kalo, the first polarizing dividing prism and the second partially transmitting output mirror form a second standing-wave optical resonator, and the linearly polarized optical radiation of the first resonator from the partially transmitting first output mirror is reflected from the semitransparent plate, the linearly polarized optical radiation of the second resonator, mutually orthogonal to the radiation of the first resonator , from the output of the partially transmitting second output mirror passes through a translucent plate, m spatially combined radiation of both resonators from the exit of the translucent plate, passing through the polarizer, ensuring their interference, is fed to the input of the photodetector.