JPH08211337A - Optical antenna for loading on satellite - Google Patents

Abstract

PURPOSE: To detect positional deviation and slope between a main reflection mirror and a sub-reflection mirror. CONSTITUTION: This device is provided with the main reflection mirror having an opening 1a on a central part, the sub-reflection mirror 2 disposed to face oppositely on the optical axis of the main reflection mirror 1, a support 3 supporting and fixing between the main reflection mirror 1 and the sub-reflection mirror 2 at a prescribed interval, reference light sources 4, 5 attached to the peripheral part of the sub-reflection mirror 2 in axial symmetry, a half prism 6 arranged on the rear surface side of the main reflection mirror 1 coaxially with the opening 1a, the reference light source 8 arranged on the optical axis of the half prism 6, a quadrant photodetector 9 having plural photoelectric conversion sensors 9a-9d dividedly arranged coaxially with the opening 1a of the main reflection mirror 1, the half prism 6 and the reference light source 8 and an angle detection processing circuit 10 operation processing level differences of output voltages outputted from respective photoelectric conversion sensors 9a-9d of the photodetector 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite-mounted optical antenna for transmitting and receiving optical signals in optical communication between satellites, and more particularly to a positional deviation in the optical axis direction between a main reflecting mirror and a sub-reflecting mirror. The present invention relates to a detection structure for detecting the tilt of a sub-reflecting mirror.

[0002]

2. Description of the Related Art Conventionally, as an optical antenna of this type, a main reflecting mirror and an opposing sub-reflecting mirror are coaxially mounted and supported by a supporting body so as to be adjustable. A cylindrical body that penetrates through the sub-reflector is attached to the sub-reflecting mirror, and transparent targets that show color in the part that receives the laser light are attached to both ends of the cylinder to adjust the tilt and decentering of the sub-reflecting mirror. A Cassegrain type antenna has been proposed which can be easily and quickly performed. An optical antenna of this type is disclosed in, for example, Japanese Patent Laid-Open No. 63-269504.
It is disclosed in Japanese Patent Publication No.

[0003]

However, when this type of optical antenna is used as a satellite-mounted optical antenna, it has the following problems. Measures the positional deviation in the optical axis direction (deviation in the direction perpendicular to the optical axis) and the inclination of the secondary reflecting mirror (angle of inclination of the optical axis) between the main reflecting mirror and the sub-reflecting mirror in an orbital environment. It does not have the function to do. Further, in order to achieve a high antenna gain, it is necessary to grasp the deviation between the main reflecting mirror and the sub-reflecting mirror on the orbit. In addition, it is not possible to correct the influence of the alignment of the transmitting and receiving beams due to the inclination of the sub-reflecting mirror on the orbit.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to mount a satellite capable of detecting a positional deviation and an inclination between a main reflecting mirror and a sub-reflecting mirror. The purpose is to provide an optical antenna for use.

[0005]

In order to achieve such an object, a satellite-mounted optical antenna according to the present invention has a main reflecting mirror having a light reflecting surface and an opening in the center, and this main reflecting mirror. A pair of sub-reflecting mirrors opposed to each other on the optical axis, a support for supporting and fixing the main reflecting mirror and the sub-reflecting mirror with a predetermined gap, and a first attached to the peripheral portion of the sub-reflecting mirror. And a photodetector having a plurality of divided photodetectors arranged coaxially with the opening of the main reflecting mirror and for injecting the first reference light emitted from the first reference light source; Angle detection processing circuit that calculates the level difference of the output voltage output from each optical detection sensor of the container and calculates the positional deviation in the optical axis direction between the main reflection mirror and the sub reflection mirror and the tilt of the sub reflection mirror. And are provided.

In addition, the satellite-mounted optical antenna according to another invention has a correction means for correcting the alignment of the photodetector on the optical axis between the aperture of the main reflecting mirror and the photodetector in the above structure. is there. Further, in the satellite-mounted optical antenna according to another invention, in the above configuration, the correction means is arranged coaxially with the opening of the main reflecting mirror and is the first reference light source.
And a second reference light source which is disposed on the optical axis of the half prism and emits the second reference light to the photodetector. Further, the satellite-mounted optical antenna according to another aspect of the present invention is, in any one of the above-mentioned configurations, provided with a plurality of first reference light sources in axial symmetry on the peripheral portion of the sub-reflecting mirror.

[0007]

In the present invention, the reference light emitted from the first reference light source attached to the peripheral portion of the sub-reflecting mirror passes through the opening provided in the central portion of the main reflecting surface, and a plurality of divided light detections are performed. The output voltage that is incident on the photodetector having the sensor and is output from each photodetection sensor of this photodetector is subjected to arithmetic processing by the angle detection processing circuit, and the output voltage in the optical axis direction between the main reflecting mirror and the sub-reflecting mirror. The positional shift and the tilt of the sub-reflecting mirror are calculated.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram for explaining the configuration of an embodiment of a satellite-mounted optical antenna according to the present invention. In FIG. 1, 1 is a main reflecting mirror having a light-reflecting surface and having an opening 1a at its center, 2 is a sub-reflecting mirror that is opposed to the focal position of the main reflecting mirror 1, and 3 is a main reflection that is arranged oppositely. A support that supports and fixes the mirror 1 and the sub-reflecting mirror 2 with a predetermined gap,
Reference numerals 4 and 5 are reference light sources that are fixed to the peripheral portion of the sub-reflecting mirror 2 in an axially symmetrical manner and emit a stable level light beam.
Reference numeral 6 denotes a half prism arranged on the back side of the main reflecting mirror 1 coaxially with the opening 1a.

Further, 7 is an internal optical system which is arranged on the same optical axis as the optical axis of the half prism 6 and transmits and receives a light beam to and from the main reflecting mirror 1, and 8 is on the optical axis of the half prism 6. The reference light source 9 is a four-element photodetector disposed on the same optical axis connecting the half prism 6 and the reference light source 8. The four-element photodetector 9 has a light-receiving surface. Radially divided into four areas a (first quadrant), b (second quadrant), c
Photoelectric conversion sensors 9a, 9b, 9c, 9d are formed in (third quadrant) and d (third quadrant), respectively.

Numeral 10 designates each output Sa, Sb, Sc, Sd output from each photoelectric conversion sensor 9a, 9b, 9c, 9d output from the four-element photodetector 9 to perform arithmetic processing. This is an angle detection processing circuit that calculates the deviation between the main reflecting mirror 1 and the sub reflecting mirror 2 and the tilt of the sub reflecting mirror 2. In addition,
These half prism 6, internal optical system 7, reference light source 8, four-element photodetector 9 and angle detection processing circuit 10 are
Although not shown, the structure is provided in the optical antenna.

In such a structure, the reference light having a stable level emitted by the reference light source 4 and the reference light source 5 provided on the peripheral portion of the sub-reflecting mirror 2 is provided at the central portion of the main reflecting mirror 1. After passing through the opening 1a, the light enters the light incident surface of the half prism 6, is refracted by the half prism 6, and is divided into four areas a, b, of the four-element photodetector 9.
The light is incident on the photoelectric conversion sensors 9a, 9b, 9c, 9d of c and d, respectively.

As a result, each photoelectric conversion sensor 9a, 9
b, 9c and 9d respectively output outputs Sa, Sb, Sc and Sd corresponding to the incident light beam, and these outputs S
The angles a, Sb, Sc and Sd are input to the angle detection processing circuit 10. This angle detection processing circuit 10 receives each output S
Output voltages corresponding to a, Sb, Sc, and Sd are respectively V
Assuming a, Vb, Vc, and Vd, V1 = Va + Vb-Vc-Vd V2 = Va-Vb-Vc + Vd is calculated, and the signs of the voltage V1 and the voltage V2 are determined to obtain a reference value as shown in Table 1 below. Detect the position of light.

[0013]

[Table 1]

For example, when the reference light source 4 is turned on, FIG.
In (a), (b), and (c), as shown in Case 1, Case 2, and Case 3, spot-shaped reference light is a photoelectric conversion sensor 9a, 9b, 9c of the four-element photodetector 9. , 9d
It is supposed to be irradiated. In this case, the reference light source 4 has: Case 1: V1> 0, V2≈0 Case 2: V1≈0, V2> 0 Case 3: V1> 0, V2> 0, corresponding to the position shown in FIG. I know that Therefore, by observing the change in the image of the reference light, the positional deviation between the main reflecting mirror 1 and the sub reflecting mirror 2 in the optical axis direction and the tilt of the sub reflecting mirror 2 can be detected.

Similarly, by turning on the reference light source 5 attached to the other peripheral portion of the sub-reflecting mirror 2, the reference light source 5 is, as described above, case 1: V1 <0, V2≈0 case 2: V1 < 0, V2> 0 Case 3: V1 <0, V2> 0, and it can be seen that this corresponds to the position shown in FIG. Therefore, by observing the change in the image of the reference light, the positional deviation between the main reflecting mirror 1 and the sub reflecting mirror 2 in the optical axis direction and the tilt of the sub reflecting mirror 2 can be detected. By using it, it is possible to improve the detection accuracy.

Further, by turning on the reference light source 8 arranged in the optical antenna, the reference light source 8 is, similarly to the above, the case 1: V1≈0, V2≈0 Case 2: V1≈0, V2≈0 Case 3 : V1≈0, V2> 0, and it can be seen that this corresponds to the position shown in FIG. Therefore, by observing the change in the image of the reference light, the inclination of the 4-quadrant photodetector 9 itself can be measured,
The detection accuracy can be improved by correcting the above-mentioned measurement result using the result.

For example, assuming that the case where the positional deviation in the optical axis direction does not occur is case 1 in FIG. 2A, case 2
In such a case, since the position of the spot of the reference light source 8 is not displaced, it is estimated that the entire sub-reflecting mirror 2 is displaced in the direction corresponding to the area d. In case 3, since the spots of the three reference light sources 4, 5, and 8 are displaced in the same direction by the same amount, it can be estimated that only the 4-element photodetector 9 is displaced.

In the above-described embodiment, the case where the half prism 6 and the reference light source 8 are provided on the optical axis between the opening 1a of the main reflecting mirror 1 and the photodetector 9 has been described. Is not limited to this configuration,
Although the alignment of the photodetector 9 cannot be corrected by disposing the photodetector 9 on the same optical axis as the opening 1a of the main reflecting mirror 1, the optical axis between the main reflecting mirror 1 and the subreflecting mirror 2 cannot be corrected. It is possible to detect the positional deviation in the direction and the tilt of the sub-reflecting mirror 2.

Further, in the above-described embodiment, as a means for correcting the alignment of the photodetector, a half which is arranged coaxially with the opening of the main reflecting mirror and which receives the first reference light of the first reference light source is incident. The case where the prism and the second reference light source that is arranged on the optical axis of the half prism and emits the second reference light to the photodetector are described, but the present invention is not limited to this configuration. However, it may be configured only with a second reference light source that introduces the second reference light to the optical axis of the photodetector, or an optical system in which the second reference light source and a lens are combined may be used. Of course, even if it is used, the same effect as the above can be obtained.

[0020]

As described above, according to the present invention,
It is extremely excellent that a satellite-mounted antenna with a detection function that can detect the positional deviation in the optical axis direction between the main reflecting mirror and the sub-reflecting mirror and the tilt of the sub-reflecting mirror in an orbit environment can be realized. The effect is obtained.

Further, according to the present invention, in orbit,
Since it is possible to grasp the positional deviation in the optical axis direction between the main reflecting mirror and the sub-reflecting mirror and the tilt of the sub-reflecting mirror, pointing at a position with a misalignment and tilt can improve the directivity of the antenna gain. It is possible to obtain a very excellent effect that it can be aimed and a high antenna gain can be secured.

Further, according to the present invention, it is possible to obtain an extremely excellent effect that the influence of the alignment of the transmitted / received light due to the inclination of the sub-reflecting mirror on the orbit can be corrected.

Further, according to the present invention, since the correction means is provided on the optical axis between the opening of the main reflecting mirror and the photodetector, the alignment of the photodetector itself can be corrected and the main reflecting mirror The accuracy of measurement of misalignment with the sub-reflecting mirror can be improved, and the change in the signal level when the second reference light from the second reference light source is received is periodically measured, whereby the antenna The extremely excellent effect that the secular change of the internal optical system can be detected is obtained.

Further, according to the present invention, by providing the plurality of first reference light sources on the peripheral portion of the sub-reflecting mirror, even if the deterioration occurs due to the obstacle on the orbit, the redundant switching can be performed and the measurement can be performed. An extremely excellent effect of being able to maintain continuity is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration according to an embodiment of a satellite-mounted optical antenna according to the present invention.

FIG. 2 is a diagram showing an example of image formation of a reference light source in the 4-quadrant photodetector of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main reflecting mirror, 1a ... Aperture, 2 ... Sub-reflecting mirror, 3 ... Support, 4 ... Reference light source, 5 ... Reference light source, 6 ... Half prism, 7 ... Internal optical system, 8 ... Reference light source, 9 ... 4 elements Original photodetector, 9a ... Photoelectric conversion sensor, 9b ... Photoelectric conversion sensor, 9
c ... Photoelectric conversion sensor, 9d ... Photoelectric conversion sensor, 10 ... Angle detection processing circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H04B 10/22

Claims (4)

[Claims] 1. A main reflecting mirror having a light reflecting surface and having an opening in the center, a sub-reflecting mirror oppositely disposed on the optical axis of the main reflecting mirror, the main reflecting mirror and the sub-reflecting mirror. A support for supporting and fixing them with a predetermined space therebetween, a first reference light source attached to the peripheral portion of the sub-reflecting mirror, and a first reference light source disposed on the optical axis of the main reflecting mirror. And a photodetector having a plurality of divided photodetection sensors for injecting the first reference light emitted from the reference light source, and a level difference between output voltages output from the photodetectors of the photodetectors. And an angle detection processing circuit for calculating the positional deviation in the optical axis direction between the main reflecting mirror and the sub-reflecting mirror and the inclination of the sub-reflecting mirror. 2. The satellite mounting light according to claim 1, further comprising a correcting unit for correcting alignment of the photodetector on an optical axis between the opening of the main reflecting mirror and the photodetector. antenna. 3. The half prism according to claim 2, wherein the correction means is disposed coaxially with the opening of the main reflecting mirror and which receives the first reference light of the first reference light source, and the half prism. An optical antenna for mounting on a satellite, comprising: a second reference light source which is disposed on the optical axis of a prism and emits a second reference light to the photodetector. 4. The satellite-mounted optical antenna according to claim 1, 2 or 3, wherein a plurality of the first reference light sources are provided axially symmetrically on the peripheral portion of the sub-reflecting mirror. .