SU1299319A1 - Device for measuring absolute value of free fall acceleration - Google Patents

Abstract

The invention relates to gravimetry. The purpose of the invention is to improve the accuracy and reduce the measurement time on a movable base. The invention provides for the installation near the splitter of an interferometric prism detection system with three reflecting faces, which returns the light beam back to the incident light reflector. As a result, the displacement of the beam on the photodetector, caused by horizontal accelerations and inclinations of the instrument, is eliminated, resulting in improved measurement accuracy. 1 hp f-ly, 2 ill. "(L yu (X with OO

Description

The invention relates to gravimetry, in particular, to absolute measurements of gravity.

The aim of the invention is to increase the accuracy and shorten the measurement time under conditions of horizontal accelerations and tilts of the base of the device.

1, a block diagram of the device is shown; in fig. 2 shows a top view of a prism and a corner reflector of a falling body (the signs показаны show the rays going upwards and the signs ® show the rays going down; their areas of location are shown)

At a certain displacement of the center of the corner reflector (as indicated by the arrow and indicated by a dash-dotted line) there is a two-fold greater displacement of the beam going down from the corner reflector to the prism.

The device contains a catapult 1, an incident body 2 placed in a vacuum chamber 3, a laser source 4 of monochromatic light with a collimator forming a parallel beam, and a laser wavelength stabilizer (not shown), a beam splitter 5 placed in a prism 6 along the path of the collimated laser beam , angular reflector 7 of the reference arm, a photodetector 8 with a pulse shaping amplifier (not shown) are placed at the output of the interfering beams and connected to the meter 9 a path and time measurement system 10, to which the generator of the reference frequency 11 and the processing system 12 are connected, connected to the output system 13 Laser source 4, beam splitter 5, prism 6, corner reflector 7 and photodetector 8 are located in housing 1 mounted on gyro platform 3

The device works as follows.

The catapult 1 throws the falling body 2 with a retroreflector, which begins free movement in the vacuum chamber 3. The beam of light from the laser 4, stabilized along the wavelength, passed the collimator, is divided by the beam splitter 5 into two beams.

The first beam (working) is directed to the light reflector of the falling body 2 and, reflected from it, is returned back by the prism 6 to the light 5

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the return and then return to the beam splitter,

The second beam (reference) pass beam splitter 5, falls on the corner reflector 7 of the reference arm of the interferometer, which returns it to the beam splitter 5, where it interferes with the first rays. The interference pattern arising from the combination of light rays is projected onto the photodetector 8, where the modulated light flux is converted into electrical signals at a frequency proportional to the speed of the incident body, and these electrical signals are amplified, which then enter the 9-way meter. The meter generates the path interval signals traveled by the free-falling body 2, which are measured by the time measurement system 10, synchronized by the reference frequency generator 11. After that, the information processing in the system 12 and the measurement results are output in the system 13. During the entire measurement process, the housing 14 is stabilized relative to the horizontal plane by the gyroplatform 15.

When measured on a movable base, horizontal displacements of the body 2 relative to the body 14 occur. Due to such movements, the working beam, reflected from the retroreflector of the falling body 2, also shifts from its original position in the same direction to a double value where the retroreflector of the falling body is displaced.

The prism ensures that the beam reflected from it hits the retroreflector with the same offset as that of the beam that emerged from the retroreflector. In this case, the total displacement of the beam after repeated reflection from the retroreflector is always zero, as a result of which the first beam always interferes with the second signal at the same point on the surface of the photoreceiver 8, regardless of the relative horizontal displacements of the falling body 2.

A corner reflector is used as a retroreflector, which is divided by ribs and their reflections in opposite faces into six sectors. The beam is preferably directed to the line dividing the sector in half.

The simplest prism to compensate for the horizontal displacements of a falling body is a prism with three reflectors, having in the main section an equilateral equilateral triangle. It performs a constant displacement of the beam, equal in magnitude to its basis. When the beam hits the edge of the prism, measurements become impossible. Therefore, the areas in which the incident on the prism and the reflected beam were located would be areas bounded by non-intersecting cylinders and the guides would be radii with twice the maximum allowable horizontal displacement of the falling body.

Claims (2)

1. A device for measuring the absolute value of the acceleration force of gravity, containing a radiation source, a falling body with a retroreflector, driven by a direct trihedron, placed in a vacuum chamber, an interferometer with an optical block for compensating the horizontal displacement of the incident different in that. bodies that, in order to improve accuracy and reduce the measurement time under conditions of horizontal accelerations and tilts of the base of the device, the optical unit compensating the horizontal displacement of the falling body is made in the form of a prism with a beam deflection of 180, reduced to an equivalent mirror with a basis of equivalent techniques set so that the plane of the specified mirror was perpendicular to the working beam and the beam deflected from it fell on the trihedron of the incident body, the prism with the radiation source, interferometer and photoreceiver to become gyro-stabilized platform on the horizon. 2. A device according to claim 1, characterized in that the prism basis is equal to four times the maximum horizontal displacement of the falling body, wherein the prism is positioned so that the plane containing the incident and reflected rays and the plane containing the optical center of the specified trihedron and the beam going from the splitter on the falling body, did not match. Editor T.Ivanova Compiled by N.Kslosnitsh Tehred M. Khodanych Akaz 739 Circulation 522Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, Projecto st., 4 - (Rig.2. Proofreader M. Pojo