RU2458368C1 - Angle reflector - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: angle reflector is made, for example, from quartz in form of a prism with lateral faces 2, 3, 4, in form of a triangle on which there is a reflecting coating. The entrance refracting face 5 of the prism is coated by a dielectric film in form of a circular zone 6 which satisfies the following condition: S_cir.zone=1/2S_entr.face, where: S_cir.zone is the area of the circular zone of the dielectric film, S_entr.face is the area of the entrance refracting face of the prism, wherein the dielectric film is made, for example, from quartz, with thickness h, which satisfies the condition: h=λ/4(n-1), where λ is the radiation wavelength, n is the refraction coefficient of the material of the film, and is deposited such that a circular beam pattern of reflected radiation is obtained.

EFFECT: high reliability and accuracy of location owing to more energy which is distributed on the periphery of the reflected laser beam, high signal-to-noise ratio.

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Description

The invention relates to location technology and can be used as a reflecting element in satellite laser ranging for accurate determination of the coordinates of navigation and geodetic satellites.

Known corner reflector [1], made in the form of a tetrahedron with three metallized reflective faces, in which two dihedral angles are π / 2, and the third is π / 2 (S + 1), where s 1, 2, 3, 4. Lengths its ribs R1, R2, R3 are selected from the ratio R1: R2: R3 = a: a: 1.

Also known is a prismatic corner reflector [2], made in the form of a trihedral pyramid, the dihedral angles between the side reflective faces of which are also equal to π / 2, π / 2 and π / 2 (S + 1), where S is a positive integer, the edges of the reflector made with sizes P1 and P2, determined from mathematical relations. The refractive index of the material of the reflector is also determined from the above ratio.

Known corner reflectors are used to provide reflection of laser radiation from various objects, including Earth satellites, strictly in the opposite direction to the transmitter.

A disadvantage of the known technical solutions is that due to the velocity aberration, the reflected beam returns with an offset reaching several arc seconds, which depends on the satellite’s orbit, while in the known corner reflectors [1] and [2]) the main part of the energy is in the center of the spot and wasted.

The closest to the proposed utility model in technical essence is the corner reflector [3], made, for example, of quartz in the form of a prism, the side faces of which are made in the shape of a triangle, while a layer of reflective metal coating is applied to the surface of the side faces of the prism, for example, aluminum or silver, with the fulfillment of condition S _cover. <S _{gr. Total} where S _cover. - the total area of the reflective coating, S _gr. - the total area of the side faces of the prism, and the corner reflector is made to ensure the formation of a multilobe radiation pattern with peripheral spots of illumination in its cross section.

, где i=1-3, S_покр.i. - площадь покрытия i-й боковой грани, S_гр.i.- площадь i-й грани призмы, илиIn other embodiments of the corner [3], a reflective metal coating is applied with the condition

where i = 1-3, S _{cover i.} - coverage area of the i-th side face, S _gr.i. - the area of the i-th face of the prism, or

applied with the fulfillment of condition S _{cover i.} <S _{gr. I.} where i = 1-3, S _{cover i.} - coverage area of the i-th side face, S _gr.i. - the area of the i-th face of the prism.

The disadvantages of the known device [3] are the lack of accuracy and reliability of the location for satellites, whose orbit is located at a distance of about 19,000 km from the Earth.

The technical result, which consists in increasing the accuracy and reliability of the location by increasing the fraction of energy that is distributed around the periphery of the reflected laser beam (along the periphery of the radiation pattern), as well as in increasing the signal-to-noise ratio, is achieved in the proposed corner reflector, made, for example , made of quartz in the form of a prism with side faces in the shape of a triangle on which there is a reflective coating, is achieved by the fact that a dielectric film in the form of a circle is deposited on the input refracting face of the prism zone with the following conditions:

_Kr.zony S = _^1/2 S _vx.gr. where

S _cr.zone - the area of the circular zone of the dielectric film,

S _hx.gr. is the area of the input refracting face of the prism, and the dielectric film is made, for example, of quartz oxide with a thickness h satisfying the condition: h = λ / 4 (n-1), where λ is the radiation wavelength, n is the refractive index of the film material, and plotted to provide a ring radiation pattern of reflected radiation.

The essence of the utility model is illustrated by drawings:

- figure 1 shows a view of the side face of the reflective corner;

- figure 2 shows a view of the input face of the corner;

- figure 3 shows a view of the input face of the corner;

- figure 4 shows a corner in section with incident and reflected laser radiation;

- figure 5 shows the diffraction pattern in the far zone;

- figure 6 shows the dependence of illumination on the angular distance to the axis of the reflected beam from the EO with a film deposited on the input face.

The corner reflector is made in the form of a prism 1 (Fig. 1) with three side faces 2, 3 and 4 and an input front face 5.

A thin silicon oxide film 6 of a circular shape with an area of S _cr.zone is applied to the frontal front face 5 in such a way that it covers half of the area S _in..g. input face 5 of the corner reflector.

The proposed corner reflector operates as follows.

A beam of incident laser radiation 9 (Fig. 4) enters the corner reflector 1 through its input (frontal) face 5. After complete internal reflections from the side faces 2, 3, and 4, the reflected laser beam leaves the reflector 1 through the front face 5 in the direction 10 opposite to the direction of fall.

For the satellites of the GLONASS navigation system, the optimal shape of the illumination distribution has the form of a ring with an angular distance to the axis of approximately five angular seconds (Fig. 5).

The diffraction pattern in the far zone and the dependence of illumination on the angular distance to the axis of the reflected beam from the corner reflector 1 with a film 6 deposited on the input face 5, shown in Fig.6.

The thickness of the film 6 should provide a phase shift between the Central and peripheral beam equal to π. The interference of these parallel beams in the far zone (at infinity) leads to the extrusion of energy to the periphery of the reflected beam.

A corner reflector with a coating pattern applied to its face is a radial amplitude-phase diffraction element whose properties depend on the state of polarization of the incident radiation. This provides a special kind of radiation pattern in the far zone and allows one to control both its angular width and the energy distribution inside it.

Retroreflector systems based on corner reflectors are installed on geodetic and navigation satellites to reflect the beam of a laser rangefinder. Measurement of the laser pulse path time allows one to determine with high accuracy the parameters of the satellite’s orbit and the coordinates of a ground station. The side faces of 2,3,4 corner reflector 1, as a rule, are made with a metal coating of aluminum or silver. If all dihedral angles do not deviate from 90 °, then the distribution of the reflected light intensity in the far zone is an Airy diffraction pattern with an angular width of the central maximum between the first zeros of 2γ≈2.44λ / D, where D is the diameter of the aperture of the VO.

The specifics of the use of UO in satellite ranging systems is that the reflected laser beam deviates from the direction to the transmitter due to the so-called high-speed aberration phenomenon, and the deviation angle is 2 u / s, where u is the tangential component of the satellite’s speed, and c is the speed Sveta. This deviation depends on the satellite’s orbit and can reach about 10 arc seconds at low altitudes, which means a shift of the center of the light spot on the Earth’s surface by tens to hundreds of meters from the transmitter. Therefore, for the operation of the rangefinder system, it is necessary that the energy of the reflected laser beam be concentrated not on the optical axis, but on its periphery.

The corner reflector is made of quartz.

Geometric dimensions: each face is a triangle with sides of 24 mm, while the corners of the faces are cut for ease of fixing.

Information sources

1. RF patent for the invention No. 2020668, M. cl. H01Q 15/18, publ. 09/30/1994.

2. RF patent for the invention No. 2101740, M. cl. H01Q 15/18, publ. 09/30/1994.

3. RF patent for utility model No. 84141, IPC G02B 5/122, publ. 06/27/2009.

Claims (1)

A corner reflector made, for example, of quartz in the form of a prism with side faces in the shape of a triangle, on which there is a reflective coating, characterized in that a dielectric film in the form of a circular zone is applied to the input refracting face of the prism with the condition
_Kr.zony S = _^1/2 S _vh.gr. ,
where S _cr.zone - the area of the circular zone of the dielectric film,
S _{input gr.} - the area of the input refracting face of the prism,
moreover, the dielectric film is made, for example, of quartz oxide with a thickness h satisfying the condition h = λ / 4 (n-1), where λ is the radiation wavelength, n is the refractive index of the film material, and is applied to obtain a ring radiation pattern of reflected radiation .

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