JP2858488B2 - Light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source,
Particularly, the present invention relates to a beacon light source for capturing and tracking, which is required when optical communication is performed between geostationary satellites separated by about several tens of kilometers.

[0002]

2. Description of the Related Art FIG. 7 is an optical communication theory workshop, edited by Optical Communication Theory and Its Applications, Morikita Publishing, p341-p347 or literature. IEICE Technical Report SAT87-3 or literature SPIE.
vol. 810, pp215-222, pp239-
FIG. 244 is a schematic configuration diagram of a transmission / reception optical system used for conventional inter-satellite optical communication shown in 244 or the like. FIG. 8 is a schematic configuration diagram showing a conventional inter-satellite acquisition operation, and FIG. 9 is a configuration diagram of a conventional acquisition / tracking light source. In the figure, 1 is a communication light source, 2 is a prospective angle correction optical system, 3 is a fine directional optical system, 4 is an optical antenna,
5 is a light source for capturing / tracking, 6 is a receiver, 7 is a receiver for capturing / tracking, 8 is an optical axis adjusting device, 9 is a tracking control circuit, 1
Reference numeral 0 denotes a scanning pattern generation circuit, 11 denotes a first satellite, 12 denotes a second satellite, 13 denotes a semiconductor laser diode, 14 denotes a collimating lens, and 15 denotes an anamorphic optical system.

Next, the operation will be described. Communication light source 1
In general, a GaAs semiconductor laser diode having an output of about 50 to 100 mW is used, and modulates outgoing light by modulating an injection current to transmit a communication signal. The light emitted from the communication light source 1 is converted into a parallel light beam by a lens, and is then given an angular displacement by the expected angle correction optical system 2 by the moving amount of the opposing satellite within the round trip time of the light. An angular displacement corresponding to the direction of the received beam from the opposing satellite is given by the directional optical system 3 and input to the optical antenna 4. The optical antenna 4 is generally a reflection type telescope which can be reduced in size and weight. When the wavelength is 0.8 μm, the communication beam width emitted from the optical antenna 4 having a diameter of 20 cm is 4 μrad.
(16 m for a 40000 km oncoming satellite).

On the other hand, a beam for acquisition and tracking requires a wide beam width in order to cause an oncoming satellite to perform acquisition and tracking. Especially in the initial acquisition, the position of the partner satellite, the attitude of the own satellite,
The uncertain viewing angle is determined by the accuracy of mounting the communication device to the satellite body, the accuracy of attitude determination, etc., and the uncertain viewing angle is about ± 0.2 degrees (7 mr
ad) (280 km at 40000 km)
This width is required for the tracking beam width. However, if the beam width is widened, the power received by the oncoming satellite decreases, so that a capturing / tracking light source 5 having a large output is required to establish a capturing / tracking line (1 to 10 W). .

At present, the output of a semiconductor laser diode (LD) having a single active layer and oscillating in a single lateral mode is at most about 100 mW in consideration of reliability. Also, the phase synchronization L
If a D array is used, an output of about several W can be obtained.
There is a problem that the output direction and the pattern change due to output fluctuation and the like. Nd: YAG laser, CO ₂ laser
Although it is conceivable to use a laser or the like as the light source 5 for capturing and tracking, it is best to use a semiconductor laser diode in consideration of miniaturization, reliability, power consumption, price, and the like.

Therefore, as a light source 5 for capturing and tracking, FIG.
As shown in FIG.
Using the output semiconductor laser diode 13, the collimating lens 14 is slightly defocused to collimate the light emitted from the semiconductor laser diode 13 slightly more than the diffraction limit. The spread angle of the light emitted from the semiconductor laser diode 13 is wide in the vertical direction of the active layer and narrow in the horizontal direction of the active layer, reflecting the shape of the active layer, so that the intensity distribution of the collimated light has an elliptical shape. This is converted into a circular shape by an anamorphic optical system 15 using a prism pair or the like. As a result, the spread angle becomes equal in the vertical direction of the active layer and in the horizontal direction of the active layer. Thereafter, the light passes through the prospective angle correction optical system 2 and the fine directing optical system 3 and exits from the optical antenna 4.

As shown in FIG. 8, for example, a beam for capturing and tracking emitted from the satellite 1 is a scanning pattern generating circuit 10.
Is scanned within the uncertain viewing angle between the satellites by the optical axis adjusting device 8 controlled by. The scanning time is determined from the time required for capturing the oncoming satellite and the like, and is usually about 1 minute. The capture / tracking beam emitted from the oncoming satellite enters the optical antenna 4 and is received by the capture / tracking receiver 7. The acquisition / tracking receiver 7 includes a two-dimensional CCD array having an uncertain viewing angle,
A four-element detector having a viewing angle of about the resolution of a CD array is used, and a tracking control circuit 9 provides a negative feedback to the optical system axis adjusting device 8 and the fine directing optical system 3 based on the error signal generated here. And tracking is performed. Generally CCD array
When the capturing / tracking beam is scanned at the time when the capturing is performed, the pointing error angle between the satellites falls within the communication beam width by performing the capturing / tracking. The communication beam enters from the optical antenna 4 and is received by the receiver 6. The receiver 6 is Si-
APD or the like is used.

[0008]

The conventional light source for capturing / tracking is configured as described above, and the output is limited. Therefore, in order to establish a capturing / tracking line, a narrow beam is required. The combi had to be scanned over a wide uncertain field of view. For this reason, there is a problem that the sequence of the scanning pattern generating circuit and the signal processing circuit for capturing becomes complicated in capturing. Further, it takes a long time to acquire, so that when the communication line is disconnected, it takes time to establish the communication line again, and there is a problem that stable inter-satellite communication cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and uses a semiconductor laser diode of the present output as a light source to provide a wide screen over the entire uncertain field of view between satellites. The aim is to obtain a light source for capturing and tracking with a wide width.

[0010]

According to the present invention, there is provided an irradiation device according to the present invention.
The light source for emitting the beam has the following features. (A) an emission point array that emits light from emission points arranged one- or two-dimensionally; (b) beam conversion means for converting the emission light emitted from the emission points into beams of substantially parallel light, respectively. c) by condensing the beam of the beam transformation the substantially parallel light converted by means in the same focal point, each beam of the substantially parallel light is an angle made with respect to the focusing point by the condenser The angle between two adjacent optical axes of the substantially parallel light beam is equal to or greater than the angle formed by the light condensing with respect to the light converging point.
And the light intensity over the entire beam width of the irradiation beam
Direction determining means for condensing light so that the variation is within 5.6 dB .

The light source according to the present invention is one-dimensionally arranged.
Emission point array portion for emitting light from the emission point, and the emission point
Outgoing light emitted from the
Beam converting means, and the beam converting means.
Direction for emitting the converted substantially parallel light beam in a two-dimensional direction
A light source that emits a beam for irradiation.
Te, said direction determining means, the optical axis of the beam of the substantially parallel light
At the same focal point on the surface containing
Condenses and includes the optical axis of the substantially parallel light beam
Emits a beam of light approximately parallel to the direction perpendicular to the plane,
Each of the substantially parallel light beams is condensed by the condensing.
The angle formed with respect to the point is adjacent to the above-mentioned substantially parallel light beam
Angle formed between the two optical axes with respect to the converging point by the converging
And the entire beam width of the irradiation beam
Focus so that the light intensity variation at
It is characterized by doing.

[0012]

[0013]

In the light source according to the present invention, the emission point array section has a plurality of (N) emission points. Thus, the capture and tracking is performed by using the N semiconductor laser diodes. The output of the light source is N times larger, and the maximum beam width that can establish a line can be increased by .DELTA.N times as compared with the case where an individual semiconductor laser diode is used. However, if the outputs of the N light emitting points are transmitted as they are, the oncoming satellite receives all the outputs from the N light emitting points, so the capturing and tracking receiver forms an image of the N points and the capturing and tracking is not performed. It will be difficult. The outgoing light from the light source for capturing and tracking according to the present invention irradiates individual regions in the distance by the outgoing point array section, the beam converting means, and the direction determining means. It illuminates the entire area within the uncertain field of view required for capturing a satellite. 1 on opposite satellite
Since only the outputs from the three light emitting points are received, only one point is imaged by the capture / tracking receiver, and capture / tracking can be easily performed.

[0014]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a configuration diagram of an embodiment of the present invention. In the figure, 1
6-1~16-N ² is semiconductor laser - Zadaio - de, 17-
1 to 17-N ² is a condenser lens, is 18-1 to 18-N ² singlemode - mode optical fiber, 19 micro Enz array -,
Reference numeral 20 denotes a telecentric lens . In addition, P is a light condensing point, 31 is an optical axis, and 32 is a boundary line of light rays formed around the optical axis 31. Reference numeral 51 denotes an emission point array, 5
2 the beam converting means 3 is the direction determining means. In the drawing, broken lines indicate the flow of light rays.

Next, the operation will be described. N ² pieces of single YOKOMO - semiconductor perform de oscillation Re - Zadaio - de 16-1～
16-N, respectively condenser lens outgoing light of ² 17-1～1
Mode optical fiber 18-1～18- - singlemode by 7-N ²
It is incident on N ² . Single mode optical fiber 18-1 to 1
8-N ² exit end is aligned mode to N × N in the fiber core distance D as shown in FIG. 2 - are field, also are polished so no step (emitting point array section 51). Since the outer shape of the fiber is made with high accuracy, an N × N fiber array can be manufactured with high accuracy and the molding can be easily performed. The light emitted from the fiber end has a divergence angle θ ₀ (e- ² full width) determined by the mode field diameter in the fiber.
These emitted lights are also aligned at the interval D, and the N ^{2 of the} focal length f1 located at the position corresponding to each fiber emission position.
The light is collimated by the microlens array 19 composed of a plurality of lenses (beam conversion means 52). The microlens array 19 has a focal length of 0.5 mm to 3 mm and D = 0.
Those having a size of about 2 mm to 1 mm are commercially available from Corning Corporation. Each of the parallel lights is condensed at the focal position by the telecentric lens 20 having a focal length f2 set with the center of gravity of the N parallel lights as the optical axis, and spread again.
The light emitted from the optical antenna 4 (direction determining means 53) is used as trapping / tracking light.

At this time, the capture / tracking light beam width is set to θ _T (e
^If the focal lengths f1 and f2 satisfy the following formulas (1) and (2), the field pattern of the light emitted from the optical antenna 4 is M: Is as shown in FIG. 3, and each LD emitted light is captured and tracked.
A part of the beam width, and the light intensity variation over the entire capture / tracking beam width is within 5.6 dB.

[0017] f1 = D / (2 · tan (θ 0/2)) (1) f2 = N · D / (2 · tan (θ T · M / 2)) (2)

[0018] be described with reference to the relationship in Figure 1, with respect to the focal point P, the boundary line 3 2 the optical axis 31 of two adjacent to the angle A is equal to angle B (A = B ). By setting A = B in this way, as shown in FIG. 3, it is possible to keep the variation in light intensity within 5.6 dB.

At this time, since only one capture / tracking beam is emitted from each semiconductor laser diode 16 within the field of view of the satellite, only one error signal is required at the time of tracking. Tracking becomes possible.

As an example, θ _T is an uncertain viewing angle between satellites ± 0.2 degrees (7 mrad), θ ₀ is 10 degrees, and D is 2
Assuming that 50 μm, M is 10 times, and N is 5, f1 = 1.
4 mm, f2 = 17.8 mm. Assuming that the output light power of each semiconductor laser diode 16 is 100 mW, the coupling efficiency of the laser light to the single mode optical fiber 17 is -3 dB, and the other loss is 1 dB. About 1 W is obtained as an optical output. In order to further increase the output, N may be increased.

As described above, in this embodiment, a light source for capturing / tracking which converts the light emitted from a semiconductor laser diode oscillating in a horizontal single mode into a predetermined beam width and transmits the converted light is described. , N semiconductor laser diodes are two-dimensionally arranged, and the N semiconductor laser diode emitted lights are two-dimensionally aligned at equal intervals. An emission point array for converting the emission lights from the emission points having the aligned axes, and the emission lights from the aligned N emission points are two-dimensionally maintained while keeping their optical axes parallel. Beam converting means for converting the aligned N substantially parallel lights into light, and direction determining means for condensing the N substantially parallel lights at the same converging point; Is the angle A formed by the light collection with respect to the light collection point, and the two adjacent light beams of the N parallel lights Axis has been described acquisition and tracking light source that features that it has to be equal to angle B which forms with respect to the focusing point by the condenser.

Each of the N semiconductor laser diode emitted lights is converted into an emitted light from an emission point having two emission optical axes aligned two-dimensionally at equal intervals. As the emission point array portion, N single-mode optical fibers 18 and the N semiconductor laser diodes 16 are used.
Means 17 for inputting each of the outgoing light beams from one of the end faces of the N single-mode optical fibers and the other of the end faces of the N optical fibers are two-dimensionally aligned and fixed at equal intervals. A case has been described in which the other end faces of the integrated N optical fibers provided with the fixing means are polished simultaneously.

Embodiment 2 FIG. FIG. 4 is a block diagram showing another embodiment of the present invention. In the figure, reference numeral 21 denotes the number of active layer waveguides N, each interval is D, and the spread angle θ _{0V of} each emitted light in the vertical direction of the active layer.
(E- ² full width), spread angle θ _{0H in the} horizontal direction of the active layer (e- ²
A semiconductor laser array 22 in which each active layer waveguide is not phase-locked; and 22 is an anamorphic telecentric lens having a refractive power of a focal length f2 only in the horizontal direction of the active layer of the semiconductor laser array 21. , 23 have a focal length f3 only in the direction perpendicular to the active layer of the semiconductor laser array 21.
A cylindrical lens that have a refractive power.

The light emitted from the semiconductor laser diode array 21 is separated from the light exit surface by a focal distance f1 by a microlens array 19 provided at an interval D corresponding to each active layer waveguide position. It is collimated (beam conversion means 52). Thereafter, the light is condensed by the anamorphic telecentric lens 22 in the direction parallel to the active layer, and by the cylindrical lens in the direction perpendicular to the active layer, and thereafter emitted from the optical antenna 4 (direction determining means 53). The focal lengths f1, f2, and f3 are calculated by the equations (3), (4), and (5).
In this case, the field pattern of the light emitted from the optical antenna 4 is as shown in FIG. 5, and each LD emitted light forms a part of the capture / tracking beam width, and the capture / tracking is performed. The light intensity variation over the entire beam width is within 5.6 dB.

F1 = D / (2 · tan (θ _0H / 2)) (3) f2 = ND · (2 · tan (θ _T · M / 2)) (4) f3 = f1 · tan (θ _{0V / 2) / tan (θ} T · M / 2) (5)

In the above embodiment, the semiconductor laser array 21 having N active layer waveguides has been described as an emission light source. The same effect can be obtained by using the fiber array as the light source of the above embodiment by injecting the light into the N single-mode optical fibers 18 whose emission ends are arrayed. . In this case, θ _0H and θ _0V in Equations (3) and (5) are defined as θ ₀ , where the divergence angle of each optical fiber output light is θ _0.
From Equations (3), (4), and (5), f1, f
2, f3 is obtained

As described above, according to the second embodiment, in the capturing / tracking light source for converting the light emitted from the semiconductor laser diode into a predetermined beam width and transmitting the converted beam, N semiconductor laser diodes are used. An emission point array for converting each of the outgoing light beams into N outgoing light axes aligned one-dimensionally at equal intervals, and outgoing light beams from the N outgoing light points arranged in a line. Beam converting means for converting each of the outgoing lights into one-dimensionally aligned substantially parallel lights while keeping their optical axes parallel, and the N directionally aligned one-dimensionally aligned substantially parallel lights in an alignment direction And an alignment direction condensing means (part of the direction determining means) for converging light to the same condensing point, and the N one-dimensionally aligned substantially parallel lights perpendicular to a plane including the arrangement direction and the optical axis. Vertical light collecting means (part of the direction determining means) for collecting light in various directions, An angle between each of the N one-dimensionally aligned substantially parallel lights with respect to the converging point by the alignment direction condensing means is adjacent to the N one-dimensionally aligned substantially parallel lights. The light source for capturing / tracking has been described, wherein the angles formed by the two optical axes with respect to the converging point by the converging direction converging means are equal.

An emission point array for converting each of the N semiconductor laser diode emission lights into N emission light axes aligned one-dimensionally at uniform intervals and having aligned emission optical axes. As described above, a light source for trapping and tracking, which uses a semiconductor laser array in which active layer waveguides are formed at equal intervals, has been described.

Further, the N semiconductor laser diodes
N single-mode optical fibers as an output point array unit that converts each of the output light beams into N output light beams aligned one-dimensionally at equal intervals and having aligned output optical axes;
Means for inputting each of the N semiconductor laser diode output lights from one of the end faces of the N single-mode optical fibers; A light source for capturing and tracking, characterized in that the means for one-dimensionally aligning and fixing the light source and the other of the end faces of the N optical fibers provided with the fixing means and polished at the same time, are simultaneously polished.

Embodiment 3 FIG. In FIG.
Numeral -N is a fiber collimator constructed by installing lenses having a focal length f1 at regular intervals with respect to the emission ends of the single-mode optical fibers 18-1 to 18-N, such as a GRIN lens or the like. It is manufactured by bonding a lens to an optical fiber or the like (beam conversion means 52). Semiconductor laser diode 16
-1 to 16-N are emitted from the condenser lenses 17-1 to 17-.
N impinges on a single mode optical fiber. The fiber collimators 24-1 to 24-N are arranged so that the optical axes of the light emitted from the respective fiber collimators pass through the converging point P in the same plane with respect to the converging point P, and have a concentric circular shape with a radius R. And the angle Mθ _T
/ N intervals (emission point array unit 51). Collimation
The light exiting from the lens 24 is condensed by the cylindrical lens 23 having a focal length of f3 only in a direction perpendicular to the plane defined by the optical axes of the light emitted from the respective fiber collimators, and then emitted from the optical antenna 4 (direction). Determination means 53). Focal length f1, f
3 has the relationship of Expressions (6) and (7), the optical antenna 4
The field pattern of the emitted light is the same as in FIG. 5, and each LD emitted light forms a part of the width of the capture / tracking beam, and the light intensity over the entire width of the capture / tracking beam. The variation is within 5.6 dB.

[0031] f1 = 2 · N · λ / (θ T · M · tan (θ 0/2)) (6) f3 = f1 · tan (θ 0/2) / tan (θ T · M / 2) ( 7)

As described above, in this embodiment, in the light source for trapping / tracking which converts the light emitted from the semiconductor laser diode into a predetermined beam width and transmits it, N semiconductor laser diodes are used.
Outgoing light from the N outgoing points where the outgoing optical axis passes through an arbitrary point in space and the distance to this arbitrary point is constant, and the adjacent outgoing optical axes And a direction determining means for converting the light emitted from the N emission points into an arbitrary spread angle while maintaining the optical axis. The light source for capturing and tracking has been described in which an arbitrary angle formed by the adjacent emission optical axes is made equal to the arbitrary spread angle.

[0033]

According to the light source according to the present invention, the outputs of a large number of light sources in which the emission points are arranged can be combined to illuminate the entire area within the uncertain field of view required for capturing the beacon beam. It does not require scanning of the beacon beam and does not require a complex sequence of captures. In addition, since communication can be constantly performed during communication, stable inter-satellite communication can be performed without disconnecting the communication line.

[0034]

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a capturing / tracking light source according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a molded single-mode optical fiber emitting end;

FIG. 3 is a field pattern diagram of trapped / tracked light according to the first embodiment.

FIG. 4 is a configuration diagram of a capturing / tracking light source according to a second embodiment of the present invention.

FIG. 5 is a field pattern diagram of captured / tracked light according to a second embodiment.

FIG. 6 is a configuration diagram of a capturing / tracking light source according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a transmission / reception optical system used for inter-satellite optical communication.

FIG. 8 is a schematic configuration diagram showing a conventional inter-satellite acquisition operation.

FIG. 9 is a configuration diagram of a conventional capturing / tracking light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication light source 2 Prospect angle correction optical system 3 Fine directional optical system 4 Optical antenna 5 Acquisition and tracking light source 6 Receiver 7 Acquisition and tracking receiver 8 Optical system axial length generator 9 Tracking control device 10 Scanning pattern generation circuit Reference Signs List 11 first satellite 12 second satellite 13 semiconductor laser diode 14 collimating lens 15 anamorphic optical system 16 semiconductor laser diode 17 condensing lens 18 single mode optical fiber 19 micro lens array -20 Telecentric lens 21 Semiconductor laser array 22 Anamorphic telecentric lens 23 Cylindrical lens

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification code FI H04B 10/00 H04B 7/15 Z 10/22 (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 27/10 H04B 10/00

Claims (2)

(57) [Claims] 1. It has the following elements and emits an irradiation beam.
Light source (a) 1 or exit point sequence unit for emitting light from the emission point arranged in a two-dimensional, (b) beam converting means for converting emitted from the emitting point were the outgoing light beam of each substantially collimated light , (c) is focused the beam of the beam transformation the substantially parallel light converted by means in the same focal point, each beam of the substantially parallel light makes with the focusing point by the condenser The angle is greater than or equal to the angle formed by the converging between two adjacent optical axes of the substantially parallel light beam with respect to the converging point.
And the light intensity over the entire beam width of the irradiation beam
Direction determining means for condensing light so that the variation is within 5.6 dB . 2. Light is emitted from emission points arranged one-dimensionally.
Emission point array part, and the emission light emitted from the emission point is substantially parallel light.
Beam converting means for converting into a beam, and a beam of substantially parallel light converted by the beam converting means
Direction determining means for emitting light in a two-dimensional direction;
A light source for emitting a beam, wherein the direction determining means includes an optical axis of the substantially parallel light beam;
Focus the above parallel light beam on the same focal point on the other side
Along with the surface containing the optical axis of the above-mentioned substantially parallel light beam.
A beam of substantially parallel light is emitted in the direction perpendicular to
Each of the beams of row light is focused on the focus point by the focus
The angle between two adjacent beams of nearly parallel light
Is greater than the angle that the optical axis of
And the irradiation beam over the entire beam width.
Focus light so that light intensity variation is within 5.6 dB
A light source characterized in that: