JP3093237B2 - Optical communication terminal - Google Patents

Description

The present invention relates to an optical communication terminal device mounted on a satellite, and more particularly to an improvement in an alignment adjustment (optical axis adjustment) mechanism.

(Prior Art) A conventional optical communication terminal device mounted on a satellite is generally configured as shown in FIG. In FIG. 5, reference numeral 11 denotes a dual-purpose telescope, reference numeral 12 denotes a fine pointing assembly (hereinafter referred to as FPA), reference numeral 13 denotes a pointer ahead assembly (hereinafter referred to as PAA), reference numerals 14 to 17 denote beam splitters, and reference numerals 18 to 20. Is the optical lens for the sensor, 21 and 22 are LD
(Laser diode) optical lens, 23 is a coarse sensor, 24 is a fine sensor, 25 is a communication sensor, 26 is a communication LD, and 17 is a beacon LD.

FPA12 is a fine sensor so that the laser beam from the partner satellite always enters the center of the field of view of the communication sensor 25 on its own satellite side.
The beam deflection angle of the laser beam is mechanically changed in accordance with the output of 24. Generally, two gimbal mirrors whose axes can be independently controlled are used to independently control the _AZ angle and the _EL angle. In the case of inter-satellite communication, PAA13 is the target position of the target satellite based on the delay time required for the laser beam transmitted toward the target satellite to reach the target satellite because the distance to the target satellite is very long. Is provided in order to prevent the laser beam transmitted to the other satellite from hitting by moving, and when transmitting a beam, the expected movement angle of the other satellite is calculated in advance, and the beam angle to be transmitted based on the predicted angle Is a beam deflecting mechanism for correcting The PAA 13 also uses two gimbal mirrors of one-axis independent control, and performs the same control as the FPA 12.

A description will be given of an operating means in a case where a satellite equipped with the optical communication terminal device having the above-described configuration performs communication with a partner satellite.

First, in order to capture the other satellite, the beacon laser light emitted from the beacon LD 17 is shown by a dashed line in the drawing, that is, the LD optical lens 12, the beam splitter 17,
PAA13, Beam splitter 15, FPA12, Beam splitter
14. Transmitted via the telescope 11, and coarsely adjusted the transmission direction of the laser light so that the beacon laser light from the partner satellite is received. After passing through the telescope 11, the beacon laser light from the partner satellite is partially reflected by the beam splitter 14 and guided to the course sensor 23 via the sensor optical lens 18. The course sensor 23 is composed of a two-dimensional CCD or the like, and detects the distance and direction from the center point of the light receiving surface to the light receiving point to detect the beacon bearing error of the other satellite. The two-axis cymbal mirror and gimbal mechanism provided on the telescope 11 are controlled according to the obtained azimuth information, and the beacon laser light is automatically added to the center point of the course sensor 23, thereby controlling the course tracking control. Do.

When the beacon laser light from the partner satellite is driven to the center point of the course sensor 23 by the course tracking control, the beacon laser light passing through the beam splitter 14 is
After passing through the FPA 12 and the beam splitters 14 and 16, the light enters the field of view of the sensor optical lens 19, which has a very narrow field of view compared to the course sensor optical system, passes through the lens 19, and enters the fine sensor 24. . The fine sensor 24 is constituted by a four-segment detector (4QD) or the like, and detects the beacon azimuth error of the partner satellite with high accuracy from the difference in the amount of received light in each segment. The direction adjustment provided in the FPA 12 is controlled in accordance with the obtained azimuth information, and the beacon laser light is automatically focused on the center point of the fine sensor 24, thereby performing fine tracking control, and performing communication with the partner satellite. Establish an optical line between them.

Once the satellite-to-satellite optical link is established, the beacon laser light is switched to a narrower communication laser light. That is, the drive of the beacon LD27 is stopped, and the LD26 for communication is driven instead, and the output laser light is transmitted to the optical lens for LD.
22, Beam splitter 17, PAA13, Beam splitter 1
5, FPA12, beam splitter 14, transmit to the other satellite via the telescope 11, the communication laser beam from the other satellite telescope 11, beam splitter 14, FPA12,
The light is guided to a communication sensor 25 such as an APD (APD: avalanche photodiode) via the beam splitters 15 and 16 and the sensor optical lens 20. Thus, an optical communication line is established. At this time, a part of the communication laser light is reflected by the beam splitter 14 and guided to the coarse sensor 23, passes through the beam splitter 16 and is guided to the fine sensor 24, and the above-described course tracking control and fine tracking control are performed. It is performed continuously, so that the optical communication line is continuously and well maintained.

By the way, in the conventional optical communication terminal device having the above configuration,
At the time of calibration, it is essential to perform alignment adjustment (optical axis adjustment) between the transmission optical system and the reception optical system and check the light intensity of the transmission light. In particular, the alignment adjustment is required to be ultra-high precision. However, the conventional apparatus does not particularly have a calibration function for alignment adjustment and for checking the light intensity of transmission light, and these adjustments are extremely difficult and time-consuming.

(Problems to be Solved by the Invention) As described above, in the conventional optical communication terminal device, it is difficult and time-consuming to adjust the alignment between the transmission optical system and the reception optical system and check the light intensity of the transmission light.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an optical communication terminal having a calibration function that can easily and quickly execute alignment adjustment and light intensity check between a transmission optical system and a reception optical system. It is intended to provide a device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, an optical communication terminal device according to the present invention comprises: (1) a plurality of beam splitters arranged on an optical axis of a transmission / reception telescope; Then, using these beam splitters to put the transmission light on the optical axis and guide it to the telescope,
Alternatively, in an optical communication terminal device that takes out received light from the optical axis and guides the received light to a light receiving unit, an initial alignment adjustment for aligning the optical axes of the transmitted light and the received light in the own device before operation or an initial adjustment of the transmitted light A reflection mechanism that is used at the time of light intensity check, is disposed on an optical axis of transmission light incident on the telescope, and reflects a transmission light incident on the telescope in a reverse direction and puts the transmission light on the optical axis of the telescope. Then, at the time of the initial alignment adjustment or the initial light intensity check, the transmitting light is sent out and enters the reflecting mechanism instead of the telescope, and the reflected light of the reflecting mechanism is received by the light receiving unit. A first feature is that the initial alignment adjustment or the initial light intensity check of the transmission light is performed based on the detection output of the unit.

(2) A plurality of beam splitters are arranged on the optical axis of the transmission / reception telescope, and the transmission light of the first wavelength is put on the optical axis using these beam splitters and guided to the telescope, or In an optical communication terminal device for extracting the second wavelength reception light from the telescope from the optical axis and guiding it to a light receiving unit, the initial alignment adjustment of the transmission light and the reception light in the own device before operation or A reflection mechanism arranged on the transmission light incident optical axis to the telescope at the time of the initial light intensity check of the transmission light, and reflecting the transmission light incident on the telescope in the opposite direction and placing on the optical axis of the telescope. Placed in front of the light receiving section, allows only light of the second wavelength to pass therethrough in the operating state, and excludes the light from the optical axis of the received light during the initial alignment adjustment or the initial light intensity check. A filter mechanism for directly inputting the light of the first wavelength reflected by the mechanism to the light receiving unit, and transmitting the transmission light of the first wavelength during the initial alignment adjustment or the initial light intensity check. The light enters the reflection mechanism instead of the telescope, and the reflected light of the reflection mechanism is incident on the light receiving unit without passing through the filter mechanism, and the initial alignment adjustment or the transmission is performed based on the detection output of the light receiving unit. A second feature is that an initial light intensity check of light is performed.

(3) In the configuration according to the first or second aspect, the reflection mechanism is positioned on the optical axis of the telescope at the time of the initial alignment adjustment or the initial light intensity check, and the reflection mechanism is placed at the telescope in an operation state. A third feature is that the light source is moved out of the optical input / output path.

(4) In the configuration according to the first or second aspect, the telescope has a main mirror and a sub-mirror, each of which has a light-transmitting center and a diameter different from each other, on the light input / output optical axis. It is of a reflection type and has a structure in which transmission light leaks through the transmission of the primary mirror and the sub-mirror to a blind spot formed on the transmission light transmission side thereof, and the reflection mechanism includes a blind spot formed on the transmission light transmission side. A shutter is fixedly arranged on the optical axis, and a shutter is provided in front of the reflection surface of the reflection mechanism, and the shutter is opened at the time of the initial alignment adjustment or the initial light intensity check, and leaks onto the optical axis of the blind spot portion by the reflection mechanism. The fourth aspect is that the transmission light is reflected in the reverse direction and guided to the light receiving unit, and the shutter is closed so that the transmission mechanism does not reflect the transmission light leaking to the blind spot in the operating state.
The feature of.

(Operation) In the optical communication terminal device configured as the first feature,
At the time of initial alignment adjustment or initial light intensity check of the transmission light to align the optical axes of the transmission light and the reception light in the own device before operation, a reflection mechanism is arranged on the transmission light incident optical axis to the telescope, The transmitted light incident on the telescope is reflected in the opposite direction to guide it to the light receiving unit,
Thus, initial alignment adjustment or initial light intensity check can be performed based on the detection output of the light receiving unit.

In the optical communication terminal device having the second characteristic, when the transmission light is at the first wavelength and the reception light is at the second wavelength, the reception light of the second wavelength is received by the filter mechanism in the operating state. When the initial alignment adjustment or the initial light intensity check is performed, the reflection light of the transmission light of the first wavelength by the reflection mechanism is guided to the light receiving unit except for the filter mechanism, so that the transmission light and the reception light have different wavelengths. However, the initial alignment adjustment or the initial light intensity check can be performed based on the detection output of the light receiving unit.

In the optical communication terminal device having the third feature, the position of the reflection mechanism can be moved between the position on the optical axis of the telescope and the position outside the light input / output path, so that the reflection in the operation state can be achieved. The influence of the mechanism is not affected, and the reflection mechanism can exhibit its function only at the time of initial alignment adjustment or initial light intensity check.

In the optical communication terminal device having the fourth feature, the telescope is formed by reflecting a primary mirror and a secondary mirror having a light transmission at the center on their light input / output optical axes and different diameters from each other. The structure is such that the transmitted light leaks through the transmission of the primary mirror and the sub-mirror to the blind spot formed on the transmission light sending side of the transmission light. The transmitted light that leaks on the axis is reflected in the opposite direction by the reflection mechanism and guided to the light receiving unit so that initial alignment adjustment or initial light intensity check can be performed, and during operation, the shutter is closed and the transmitted light that leaks to the telescope blind spot is closed. The light is not reflected, so that no trouble occurs in the operation state.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. 1 to FIG. 1 to 4, the same parts as those in FIG. 5 are denoted by the same reference numerals, and different parts will be described here.

FIG. 1 shows a first embodiment according to the present invention.
Utilizing that the laser beam transmitted from the FPA 12 is partially reflected by the beam splitter 14, a laser beam reflecting mechanism 28 is provided on the optical axis.

The laser light reflecting mechanism 28 has a shutter mechanism a, a neutral density filter b, and a corner cube c arranged in this order on the optical axis. The shutter mechanism a has a shielding plate a ₁ and a motor M ₁
A rotation drive mechanism a ₂
a ₁ is arranged on the optical axis to block the laser beam from the beam splitter 14, and the rotation drive mechanism a ₂ is used during calibration.
The driven off from the optical axis of the shielding plate a _1, and is adapted to pass the laser beam from the beam splitter 14. The laser light incident when the shutter mechanism a is opened is attenuated by the neutral density filter b, and then guided to the corner cube c. The corner cube c has a function of accurately reflecting incident light in the incident direction. That is, the laser light from the beam splitter 14 reflected by the corner cube c is again dimmed by the neutral density filter b, passes through the shutter mechanism a, and is returned to the beam splitter 14.

 The operation of the above configuration will be described below.

First, open the shielding plate a ₁ of the shutter mechanism a the time of calibration. When driving the beacon LD27 in this state,
The laser beam transmitted from the LD 27 reaches the beam splitter 14 through the above-described path. At this time, a part of the laser light is reflected by the beam splitter 14 and enters the laser light reflecting mechanism 28.

In the laser light reflecting mechanism 28, the laser light from the FPA 12 reflected by the beam splitter 14 is attenuated by the dimming filter b, and then reflected in the opposite direction by the corner cube c. Send it back to 14. The laser light reflected by the reflecting mechanism 28 in this way is partially transmitted through the beam splitter 14, guided to the course sensor 23, partially reflected and guided to the fine sensor 24, and further reflected by the beam splitter 16 It is led to the communication sensor 26. Therefore, the position and angle of each beacon optical system are adjusted so that the optical axis of the transmitted beacon laser light and the optical axis of the laser light reflected by the reflection mechanism 28 match, and the optical axis of each of the sensors 23 to 25 is further adjusted. Align so that the intersection is at the center. This completes the alignment adjustment of the beacon laser light.

The above adjustment is the same in the case of the alignment adjustment of the communication laser beam. It is also possible to check the intensity of the transmitted laser light from the output levels of the sensors 23 to 25.

FIG. 2 shows a second embodiment, assuming that the wavelength λ ₁ of the transmitted laser light (uplink) of the partner satellite is different from the wavelength λ _{2 of the} own transmitted laser light (downlink). Make up. In this optical communication device, in addition to the laser light reflection mechanism 28 shown in FIG. 1, a first filter mechanism 29 is installed in front of the sensor optical lens 18 on the optical axis toward the course sensor 23, and the beam splitters 15 and 16 are provided. Second filter mechanism 3 in between
0 is set.

The first filter mechanism 29 includes a bandpass filter d ₁ for the downlink for passing only the wavelength lambda _1, or placed on the optical axis of this filter d ₁ by the rotation of the motor M _2, or removed from the optical axis constituted by the rotary drive mechanism d ₂ for. Similarly, the second filter mechanism 30, a band-pass filter e ₁ for the downlink for passing only the wavelength lambda _1, or placed on the optical axis of this filter e ₁ by the rotation of the motor M _3, the optical axis composed of a rotary drive mechanism e ₂ to or removed from. Note that the FPA 12 automatically controls the angle adjustment in accordance with the detection output of the fine sensor 24.

That is, at the time of calibration, the filter mechanism 2
The 9, 30 bandpass filters d ₁ and e ₁ are both removed from the optical axis. As a result, the laser light of the wavelength λ ₂ transmitted from the LD for beacon 27 and the LD for communication 26 respectively passes through the paths indicated by alternate long and short dash lines, and is partially reflected by the beam splitter 14 and guided to the reflection mechanism 28. Then, the laser beam reflected by the reflection mechanism 28 is guided to the course sensor 23, the fine sensor 24, and the communication sensor 25 along a path shown by a solid line. Procedures for alignment adjustment and laser light intensity check are the same as in the first embodiment.

After the adjustment, the filters d ₁ and e ₁ are arranged on the optical axis at the same time when the shutter of the reflection mechanism 28 is closed. This reflection of the transmitted light onto the optical axis is stopped, and only the receiving laser beam having a wavelength lambda ₁ is guided to the sensors 23 to 25, is prevented interference between transmitting laser light having a wavelength of lambda ₂ is, It becomes a normal operation form.

In the first and second embodiments described above, the transmission laser light and the reflected light are multiplexed and demultiplexed at the time of calibration on the transmission laser light incident side of the telescope 11. Does not take into account adjustments. In consideration of this, the reflection mechanism shown in FIG. 3 or 4 may be provided.

FIG. 3 shows a case where the transmitting / receiving telescope 11 is of a refraction type. The reflection mechanism 31 used here can be moved to a position A on the optical axis and a position B outside the optical axis in a direction perpendicular to the optical axis on the front surface of the telescope 11, and a light-reducing filter (see FIG. the reflector f ₂ forming the shaded area) f ₁ provided, at the time of calibration is obtained by adapted back the laser beam from the telescope 11 disposed at position a in the opposite direction.

FIG. 4 shows a case where the transmission / reception telescope 11 is of a reflection type. The reflecting mechanism 32 used here utilizes the fact that the centers of the primary mirror g ₁ and the secondary mirror g ₂ of the telescope 11 that are mutually blind are open, and a mirror with a shutter is disposed at the rear of the through hole of the secondary mirror g _2. It is configured as follows. That is, the reflection mechanism in this case is passed through a hole of the secondary mirror g ₂ a part of the transmitting laser light by opening the shutter of the reflecting frame 32 during calibration, to reverse incident path is reflected by the mirror , And is incident on the inside through the telescope 11 as a reception laser beam.

By adding such a mechanism to the configuration shown in Figure 1 or Figure 2, a laser beam is dimmed from telescope 11 by the filter section f ₁ during carburetion, it is reflected by the reflecting mirror f ₂ this Since the reflected laser light can be incident on the telescope 11 as the received laser light, alignment of each optical system including the telescope 11 can be adjusted.

When the optical communication terminal device of the above embodiment is mounted on a satellite, the above-described adjustment is generally performed before the satellite is transmitted to outer space, that is, on the ground, but the alignment adjustment is performed even after the satellite is launched. Done. In this case, instead of mechanically fine-tuning the position of the sensor, the detection angle error (deviation from the center of the sensor light-receiving surface) of the received laser light detected at the time of alignment adjustment is stored, and the error angle is stored. By sending it to the satellite of the other party of the communication,
The transmission direction (angle) of the transmission laser light can be corrected.

[Effects of the Invention] As described above, according to the present invention, an optical communication terminal device having a calibration function that can easily and quickly execute alignment adjustment and light intensity check between a transmission optical system and a reception optical system. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an optical communication terminal device according to the present invention, FIG. 2 is a schematic configuration diagram showing a second embodiment according to the present invention, and FIGS. 4 is a configuration diagram showing a configuration for performing alignment adjustment including a transmission / reception telescope in the apparatus shown in FIG. 1 or 2, and FIG. 5 is a schematic configuration showing a configuration of a conventional optical communication terminal device. FIG. 11 Telecommunications telescope, 12 Fine pointing assembly (FPA), 13 Pointer ahead assembly (PAA), 14-17 Beam splitter, 18, 20 Optical lens for reception 21-22: Optical lens for transmission, 23: Course sensor, 24: Fine sensor, 25: Sensor for communication, 26: LD for communication, 27: LD for beacon, 28: Reflection of transmitted laser light Mechanism, 29,30 ……
Downlink filter mechanism, 31, 32 ... Reflection mechanism.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 G02B 7/00

Claims (4)

(57) [Claims] 1. A plurality of beam splitters are arranged on an optical axis of a transmission / reception telescope, and transmission light is put on the optical axis by using these beam splitters and guided to the telescope. In an optical communication terminal device that extracts received light from the device and guides the received light to a light receiving unit, the device is used at the time of initial alignment adjustment for aligning the optical axes of the transmitted light and the received light in its own device or the initial light intensity check of the transmitted light before operation. And a reflecting mechanism disposed on an optical axis of transmission light incident on the telescope and reflecting transmission light incident on the telescope in a reverse direction and placing the transmission light on the optical axis of the telescope, the initial alignment. At the time of adjustment or initial light intensity check, the transmission light is sent out, enters the reflection mechanism instead of the telescope, and reflects the reflection light of the reflection mechanism to the light receiving unit. Received light, optical communication terminal device being characterized in that to perform the initial light intensity check of the initial alignment, or the transmission light on the basis of the detection output of the light receiving portion. 2. A plurality of beam splitters are arranged on an optical axis of a transmission / reception telescope, and a transmission light of a first wavelength is put on the optical axis using these beam splitters and guided to the telescope. Alternatively, in an optical communication terminal device for extracting received light of a second wavelength from the telescope from the optical axis and guiding the received light to a light receiving unit, an initial alignment adjustment between the transmitted light and the received light in the own device before operation. Or it is arranged on the optical axis of the transmission light incident on the telescope at the time of the initial light intensity check of the transmission light,
A reflection mechanism that reflects transmission light incident on the telescope in the opposite direction and places it on the optical axis of the telescope, and is arranged in front of the light receiving unit and passes only light of the second wavelength in the operating state, And a filter mechanism for excluding the light of the first wavelength reflected by the reflection mechanism and directly entering the light receiving unit while excluding the light from the optical axis of the received light at the time of the initial alignment adjustment or the initial light intensity check, At the time of adjustment or initial light intensity check, the transmission light of the first wavelength is sent out, enters the reflection mechanism instead of the telescope, and receives the reflected light of the reflection mechanism without passing through the filter mechanism. Light, wherein the initial alignment adjustment or the initial light intensity check of the transmission light is performed based on the detection output of the light receiving unit. Credit terminal equipment. 3. The reflection mechanism is positioned on the optical axis of the telescope at the time of the initial alignment adjustment or the initial light intensity check, and the reflection mechanism is moved out of the light input / output path of the telescope in an operating state. The optical communication terminal device according to claim 1 or 2, wherein: 4. The telescope is of a reflection type in which a main mirror and a sub-mirror, each having a transmissive center and having a different diameter, are arranged opposite to each other on a light input / output optical axis thereof. The transmission light leaks through the transmission of the primary mirror and the secondary mirror to the formed blind spot, and the reflection mechanism is fixedly arranged on the optical axis of the blind spot formed on the transmission light sending side. A shutter is provided in front of the reflection surface of the reflection mechanism, and the shutter is opened at the time of the initial alignment adjustment or the initial light intensity check, and the transmission mechanism reflects the transmission light leaking on the optical axis of the blind spot portion in the reverse direction by the reflection mechanism. The optical communication terminal according to claim 1 or 2, wherein the light guide section guides the shutter to close the shutter in an operating state so that the reflecting mechanism does not reflect the transmission light leaking to the blind spot. Dress .