JP2022133604A - Optical transmission device and adjustment method of optical transmission device - Google Patents

Abstract

To provide an optical transmission device that can adjust the directions of a light projection optical system and a light receiving optical system with a simple configuration.SOLUTION: An optical transmission device performs optical communication between a light projection unit including emission means for emitting communication light and a light projection optical system and a light receiving unit including a light receiving optical system and light receiving means for receiving the communication light. The optical transmission device includes: a first holding member that holds the light receiving optical system; and a second holding member that holds the light receiving means and is detachably fixed to the first holding member.SELECTED DRAWING: Figure 3

Description

The present invention relates to an optical transmission device that is arranged facing a distance and performs information transmission, and an adjustment method for the optical transmission device.

The optical transmission device includes a light projecting section for transmitting communication light and a light receiving section for receiving communication light. In order to perform communication, it is necessary to align the optical axes of the optical system of the light-projecting section and the optical system of the light-receiving section.

Therefore, when installing the optical transmission devices in particular, adjusting the directions of the optical transmission devices so as to align the optical axes becomes a problem. Japanese Unexamined Patent Application Publication No. 2002-100003 discloses a technique of mounting a camera on an optical transmission device and adjusting the orientation of the optical transmission device while viewing a captured image.

Japanese Patent Application Laid-Open No. 2004-364208

However, the above conventional technology has the following problems.
Due to the fact that the optical axis of the light receiving optical system of one of the optical transmission devices and the optical axis of the camera attached to the one of the optical transmission devices do not completely match in principle, There is an essential problem that it is not easy to adjust the optical axis with sufficient precision.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical transmission device which solves the above problems and which can adjust the directions of the light projecting optical system and the light receiving optical system with a simple configuration.

An optical transmission device according to the present invention for achieving the above object comprises a light projecting section including emitting means for emitting communication light and a light projecting optical system, a light receiving optical system, and light receiving means for receiving the communication light. and a light-receiving unit including a first holding member for holding the light-receiving optical system; and a fixed second holding member.

With the configuration as described above, it is possible to provide an optical transmission device capable of adjusting the directions of the light projecting optical system and the light receiving optical system with a simple configuration.

1 is a configuration diagram of an optical transmission device according to an embodiment; FIG. It is (a) a structure detailed drawing of a light projection part, (b) principal part enlarged view. It is (a) a structure detailed drawing of a light-receiving part, (b) principal part enlarged drawing. It is the figure which removed the exchangeable holding member of the light-receiving part, and mounted the camera. FIG. 4 is a longitudinal aberration diagram for a wavelength of 1550 nm when the light receiving optical system is focused at infinity. FIG. 4 is a lateral aberration diagram for a wavelength of 1550 nm when the light receiving optical system is focused at infinity. FIG. 4 is a longitudinal aberration diagram for the e-line when the light-receiving optical system is focused at infinity. FIG. 4 is a lateral aberration diagram for the e-line when the light receiving optical system is focused at infinity.

The present invention will be described below using specific examples. In the explanatory diagrams, the scale may differ from the actual scale for the sake of clarity.

FIG. 1 is a schematic configuration diagram of a spatial optical transmission device (optical transmission device) showing an embodiment of the present invention. Although the description is for one-way communication, the same is true for reverse-direction communication.

In a spatial optical transmission device, in order to perform optical communication between a light-projecting unit that transmits communication light and a light-receiving unit that receives communication light, an optical system of the light-projecting unit and an optical system of the light-receiving unit are required. Axes must be aligned. Therefore, especially when the spatial optical transmission devices are installed, it is necessary to adjust the directions of the spatial optical transmission devices so that their optical axes are aligned. In the case of adjusting the orientation of the spatial light transmission device while looking at the photographed image by the method described in Patent Document 1, there are the following problems.

θ is the angular deviation between the optical axis of the receiving optical system of one of the spatial light transmission devices and the optical axis of the camera mounted on the one of the spatial light transmission devices, and L is the distance between the transmitting and receiving spatial light transmission devices. and When the other spatial light transmission device is captured at the center of the image of the camera, the optical axis of the light receiving optical system is directed to a position deviated from the optical axis position of the transmission side spatial light transmission device by a distance Δ=Ltanθ. It is assumed that Normally, the distance L between the spatial optical transmission devices is about several hundred meters to several tens of kilometers, and the angle deviation θ is about several minutes to several degrees. Assuming L=1 km and θ=10′, the distance Δ=1 km×tan(10′)=2.9 m, which is not sufficient for optical axis adjustment for optical communication. This can be dealt with by making the communication light divergent light instead of parallel light, or by measuring θ in advance and correcting the optical axis separation amount. decreases, and the latter requires a step of measuring θ.

In order to solve such conventional problems, the present invention provides a spatial optical transmission device capable of adjusting the optical axis direction of the spatial optical transmission device with a simple configuration and method, and the optical axis direction of the spatial optical transmission device. The purpose is to provide an adjustment method.

The communication light transmitted from the spatial optical transmission device 1000 on the transmitting side is received by the spatial optical transmission device 2000 on the receiving side at a distance, and communication is performed. The spatial optical transmission device 1000 on the transmission side has a configuration in which a light projecting section 100 for emitting communication light is mounted on an angle adjustment base 101, and the direction of the light projecting section 100 can be adjusted along two axes.

The spatial optical transmission device 2000 on the receiving side has a configuration in which a light receiving unit 200 for receiving communication light is mounted on an angle adjustment table (angle adjusting unit) 201, and the orientation of the light receiving unit 200 can be adjusted along two axes.

At the time of installation, in order to align the optical axes of the light-projecting optical system 120 (not shown in FIG. 1) of the light-projecting unit 100 and the light-receiving optical system 220 of the light-receiving unit 200, the angle adjustment base 101 and the angle The angle is adjusted by the adjustment base 201 . This ensures communication once.

However, if the free-space optical transmission devices 1000 and 2000 are continued to be used as they are, atmospheric fluctuations, vibrations of members (not shown) holding the angle adjustment base 101 and the light receiving optical system 220, environmental temperature fluctuations, and the like may occur. As a result, the optical path of the communication light fluctuates, and the communication becomes unstable. Therefore, fluctuations in the communication light are grasped by the transmission light detection unit of the light projection unit 100 and the reception light detection unit of the light reception unit 200 (composed of a transmission wedge prism 231 and a position detection sensor 232, which will be described later). Then, the optical path of the communication light is corrected to stabilize the communication. Specifically, the transmission light control unit 140 and the focus mechanism in the light projection optical system 120 (both not shown in FIG. 1), the angle adjustment table 201, the reception light control unit 240 and the light reception optical system 220, An image blur correction mechanism that moves an optical element to reduce image blur corrects the optical path of communication light and stabilizes communication.

Details of the configuration will be described below with reference to FIGS.
FIG. 2A is a detailed configuration diagram of the light projecting section 100. FIG.
The light projecting section 100 includes a communication light emitting section (projecting means) 110, a light projecting optical system 120, a transmission light detection section, a transmission light control section 140, and a holding section 150 (not shown). A communication light emitting portion (ejecting means) 110 emits communication light, and a light projecting optical system 120 substantially parallelizes the communication light emitted from the communication light emitting portion 110 and transmits it. The transmitted light detection section detects the state of the communication light transmitted from the projection optical system 120, and the transmitted light control section 140 controls the communication light.

In this embodiment, the communication light emitting section 110 is an optical fiber, and emits communication light with a wavelength of 1540 nm to 1560 nm incident from the other end (not shown). A communication light receiving section (light receiving means) 210 (not shown in FIG. 2), which will be described later, is also an optical fiber, and receives communication light at the other end (not shown). Thus, the spatial optical transmission device 1000 on the transmitting side and the spatial optical transmission device 2000 on the receiving side have substantially the same structure, and if the direction of the communication light in the optical fiber is reversed, the relationship between transmission and reception is reversed. become. Thereby, two-way communication is established.

The projection optical system 120 has a lens 121 , a lens 122 , a lens 123 , a secondary mirror (reflective curved surface) 124 , and a primary mirror (reflective curved surface) 125 . The lens 121 has an image blur correction mechanism (double-lined frame in the figure), and can finely adjust the direction of communication light by shifting (moving) in a direction perpendicular to the optical axis. Also, the lens 123 has a focus mechanism (double-lined frame in the figure), and by shifting it in the optical axis direction, it is possible to finely adjust the degree of divergence of the communication light. The primary mirror 125 has an opening with a diameter of 30 mm at its center.

The transmitted light detector is composed of reflecting prisms 131a and 131b that return part of the transmitted communication light, and position detection sensors 132a and 132b that detect the imaging positions of the returned light flux.

FIG. 2(b) is an enlarged view of the reflecting prisms 131a and 131b. By using a prism with an apex angle of α=89.9°, the communication light is shifted by 0.2° and folded back (180.2° with respect to the original direction). The folded light beam enters the light projecting optical system 120 again and is condensed on the position detection sensors 132a and 132b located at different positions from the communication light emitting section 110 because of the above-mentioned 0.2° deviation. be done. The direction of the light beam can be calculated from the imaging positions detected by the position detection sensors 132a and 132b. The reflecting prisms 131a and 131b are installed so as to reflect the communication light within a range of 1 mm at each end of the communication light beam and within a range of 5 mm in the circumferential direction around the optical axis in one cross section including the optical axis. , the divergence of the communication light can be calculated from the orientation of the rays at both ends.

Note that the position detection sensors 132a and 132b have wavelength selection filters, and the light having the wavelength of the detection light emitted by the communication light emission unit 110 of the spatial light transmission device 1000 is transmitted therethrough. Light at the wavelength of the communication light or detection light coming from the device 2000 is blocked. Such a configuration reduces erroneous detection due to stray light. In this embodiment, the wavelength of the detection light is the same as the wavelength of the communication light.

The transmission light controller 140 is connected to the position detection sensors 132a and 132b and performs the above calculations. Moreover, the calculation result is fed back to the focus mechanism of the projection optical system 120 .

The holding part 150 (not shown) has a replaceable holding member 151 and a fixed holding member 152 . The communication light emitting section 110 , the position detection sensors 132 a and 132 b that are part of the transmission light detection section, and the transmission light control section 140 are held by a replaceable holding member 151 . The projection optical system 120 and the reflecting prisms 131 a and 131 b that are part of the transmitted light detection section are held by a fixed holding member 152 together with a dustproof glass 153 . The detachable portion 151a of the exchangeable holding member 151 and the detachable portion 152a of the fixed holding member 152 are detachable. The control signal from the transmission light control unit 140 is transmitted to the light projection optical system 120 by signal transmission/reception by a mechanism (electrical contact, optical coupling, etc.) configured in the attachment/detachment unit 151a and the attachment/detachment unit 152a. is transmitted to the focusing mechanism. The fixed holding member 152 is held by the angle adjustment table 101 , whereby the spatial optical transmission device 1000 is placed on the angle adjustment table 101 .

FIG. 3A is a detailed configuration diagram of the light receiving section 200 on the receiving side.
The light receiving unit 200 includes a light receiving optical system 220 for receiving and condensing communication light, a communication light receiving unit 210 for receiving the communication light collected by the light receiving optical system 220, and a received light for detecting the state of the received communication light. It has a detection section, a received light control section 240 for controlling communication light, and a holding section. The holding portion consists of a replaceable holding member (second holding member) 251 and a fixed holding member (first holding member) 252 .

The light receiving optical system 220 has a primary mirror (reflective curved surface) 225 , a secondary mirror (reflective curved surface) 224 , lenses 223 , 222 and 221 . The lens 221 has an image blur correction mechanism (double frame in the figure), and by shifting in a direction perpendicular to the optical axis, the direction of communication light can be finely adjusted. Also, the lens 223 has a focus mechanism (double frame in the drawing), and by shifting it in the optical axis direction, it is possible to finely adjust the degree of divergence of the communication light. The primary mirror 225 has an opening with a diameter of 30 mm at its center.

The communication light receiving section 210 is an optical fiber as described above, and receives communication light at the other end (not shown). The spot diameter of the communication light condensed by the light receiving optical system 220 is 44 μm, while the core diameter of the optical fiber of the communication light receiving unit 210 is 50 μm. ing. The communication light receiving section 210 is arranged on the optical axis of the light receiving optical system 220 .

The received light detection section is composed of a transmission wedge prism 231 that refracts a portion of the incoming communication light, and a position detection sensor (detection means) 232 that detects the imaging position of the refracted light beam.

FIG. 3B is an enlarged view of the transmission wedge prism 231. FIG. The material of the transmission wedge prism 231 is s-bls7 (manufactured by Ohara, refractive index n=1.500252 at a wavelength of 1550 nm). It is refracted by 2°. The refracted light beam enters the light receiving optical system 220 and is condensed on the position detection sensor 232 at a different position from the communication light receiving section 210 because of the 0.2° deviation described above. The direction of the light beam can be calculated from the imaging position detected by the position detection sensor 232 . The transmission wedge prism 231 is installed so as to refract the communication light within a range of 3 mm at one end of the communication light and 5 mm in the circumferential direction around the optical axis in one cross section including the optical axis. From the ray orientation, the angle of arrival of the communication light can be calculated.

The position detection sensor 232 has a wavelength selection filter, and the light having the wavelength of the detection light emitted from the communication light emitting unit 110 of the spatial light transmission device 1000 passes through and comes from the other spatial light transmission device 2000. Light having the wavelength of the communication light or the detection light is blocked. Such a configuration reduces erroneous detection due to stray light. In this embodiment, the wavelength of the detection light is the same as the wavelength of the communication light.

The received light controller 240 is connected to the position detection sensor 232 and performs the above calculations. Further, the calculation result is fed back to the image blur correction mechanism of the light receiving optical system 220 and the angle adjustment base 201 (the adjustment portion is indicated by a double-lined frame in the figure). Specifically, when the fluctuation of the corrected angle of the communication light is low frequency, the angle adjustment table 201 corrects it, and when it is high frequency, the image blur correction mechanism of the light receiving optical system 220 corrects it.

A holding portion that holds the light receiving portion is composed of a replaceable holding member 251 and a fixed holding member 252 . The communication light receiving section 210 and the position detecting sensor 232 which is part of the received light detecting section are held by a replaceable holding member 251 . The light receiving optical system 220 , the transmission wedge prism 231 that is part of the received light detection section, and the received light control section 240 are held by a fixed holding member 252 together with a dustproof glass 253 . The detachable portion 251a of the exchangeable holding member 251 and the detachable portion 252a of the fixed holding member 252 are detachably connected. The control signal from the reception light control unit 240 is transmitted to and received from the light receiving optical system 220 by a mechanism (electrical contact, optical coupling, etc.) configured in the attachment/detachment part 151a and the attachment/detachment part 152a, which is capable of sending and receiving signals. It is transmitted to the focus mechanism and the angle adjustment base 201 . The fixed holding member 252 is held by the angle adjustment table 201 , whereby the spatial optical transmission device 2000 is placed on the angle adjustment table 201 .

Here, optical detailed values of the light receiving optical system 220 are shown below. As mentioned above, due to the symmetry, the optical details of the projection optics 120 are also similar. In numerical examples, for surface number i which is the order of surfaces (optical surfaces) from the object side, r is the radius of curvature of the i-th surface from the object side, and d is the i-th surface from the object side. It shows the interval (on the optical axis) of the (i+1)th surface. Also, nd and νd represent the refractive index and Abbe number of the medium (optical member) between the i-th surface and the (i+1)-th surface. The symbol * attached to the right of the surface number indicates that the surface is an aspherical surface.

単位 mm
面データ
面番号 r d nd vd 硝材
1（絞り） ∞ 1.10 1.51633 64.1 s-bsl7(ohara)
2 ∞ 150.00
3* -385.051 -140.00
4* -133.630 155.00
5 1644.588 2.00 1.56883 56.4 s-bal14 (ohara)
6 -104.907 20.00
7 -152.756 0.80 1.61800 63.3 s-phm52 (ohara)
8 29.125 16.70
9 38.931 2.50 1.56883 56.4 s-bal14 (ohara)
10 100.000 100.00
像面 ∞

非球面データ
第3面
K =-1.00000e+000
第4面
K =-2.32216e+000

各種データ
焦点距離 1600.00
Fナンバー 16.00
半画角 0.53
像高 14.80
レンズ全長 308.10 The aspheric shape is expressed by the following equation, where the X axis is in the direction of the optical axis, the H axis is in the direction perpendicular to the optical axis, the traveling direction of light is positive, R is the paraxial radius of curvature, and K is the conic constant. Also, “eZ” means “×10 ^−Z ”.

unit mm
Surface data Surface number rd nd vd Glass material
1 (Aperture) ∞ 1.10 1.51633 64.1 s-bsl7(ohara)
2 ∞ 150.00
3* -385.051 -140.00
4* -133.630 155.00
5 1644.588 2.00 1.56883 56.4 s-bal14 (ohara)
6 -104.907 20.00
7 -152.756 0.80 1.61800 63.3 s-phm52 (ohara)
8 29.125 16.70
9 38.931 2.50 1.56883 56.4 s-bal14 (ohara)
10 100.000 100.00
Image plane ∞

Aspheric data 3rd surface
K=-1.00000e+000
4th side
K=-2.32216e+000

Various data Focal length 1600.00
F number 16.00
Half angle of view 0.53
Image height 14.80
Lens length 308.10

(Features of the invention)
Characteristic configurations of the present invention will be described below.
As described above, the detachable portion 251a of the exchangeable holding member 251 and the detachable portion 252a of the fixed holding member 252 are detachably connected. Specifically, the detachable portion 251a is a C-mount female type, and the detachable portion 252a is a C-mount male type. Therefore, it is possible to remove the above coupling and couple a camera device 351 having a C-mount female mold 351a and an imaging element 352 capable of capturing a two-dimensional image as shown in FIG.

5 and 6 are longitudinal aberration diagrams at a communication wavelength (1540 nm to 1560 nm) and a focal length f = 1599.999 mm, as optical performance values of the light receiving optical system 220 when focused at infinity (the same applies to the light projecting optical system 120). Fig. 4 shows a lateral aberration diagram; 7 and 8 show longitudinal and lateral aberration diagrams at a visible light wavelength (e-line: wavelength 546 nm) and focal length f=1602.968 mm. A solid line and a dotted line in the astigmatism diagram of the longitudinal aberration diagram and the lateral aberration diagram show aberrations on the meridional image plane and the sagittal image plane, respectively. In the longitudinal aberration diagram, spherical aberration is drawn on a scale of 0.4 mm, astigmatism is drawn on a scale of 0.4 mm, and distortion is drawn on a scale of 5%. The lateral aberration diagrams of FIGS. It is a lateral aberration diagram at a height of 0.0000 mm.

5 and 6, it can be seen that the aberration can be reduced at the central angle of view of the communication light receiving section 210 at the communication wavelength (1540 nm to 1560 nm). 7 and 8, at the angle of view (23.4 × 16.7 mm = diagonal ± 14.2 mm) of the APS-C sensor (imaging device, two-dimensional image acquisition means) 352, even at visible light wavelengths, It can be seen that sufficient aberration is obtained.

That is, in this embodiment, when the spatial light transmission device 1000 is installed, the camera device 351 for visible light is attached instead of the replaceable holding member 251, and the The angle of the light receiving optical system 220 can be adjusted while viewing a two-dimensional image. In this case, since the optical axis of the camera and the optical axis of the light-receiving optical system 220 are the same, the problem of the adjustment error due to the deviation between the optical axis of the camera and the optical axis of the light-receiving optical system as in Patent Document 1 is eliminated. be canceled.

Specifically, the adjustment procedure at the time of installation is as follows.
Step 1 Confirm with GPS or the like, and adjust the angle adjustment table 101 and the angle adjustment table 201 so that the light projecting unit 100 of the spatial light transmission device 1000 and the light receiving unit 200 of the spatial light transmission device 2000 are approximately facing each other.

Step 2 In the spatial light transmission device 2000, the exchangeable holding member 251 is removed from the fixed holding member 252 together with the communication light receiving unit 210 and the position detection sensor 232 which is part of the received light detection unit, and the visible light camera is fixedly held. It is attached to the detachable portion 252 a of the member 252 .

Step 3 While confirming the two-dimensional image captured by the camera, adjust the angle adjustment table 201 again so that the spatial light transmission device 1000 comes to the center of the captured image.

Step 4 The camera for visible light is removed from the attachment/detachment portion 252a of the fixed holding member 252, and the exchangeable holding member 251 is attached to the attachment/detachment portion 252a.

In this embodiment, the position of the sensor in the camera in the optical axis direction is the same as the tip of the fiber of the communication light receiving unit 210. Therefore, in terms of design, focus adjustment is performed after step 4 is performed. No need.

Here, the spatial optical transmission device 2000 on the receiving side has been described, but the spatial optical transmission device 1000 on the transmitting side can be similarly adjusted. As a result, the directions of the bidirectional optical axes are aligned, and communication is established.

With the above configuration, the effects of the present invention can be obtained.
In this embodiment, a fixed holding member 252 that holds the light receiving optical system 220 is fixed to the angle adjustment table 201, and a replaceable holding member 251 that holds the communication light receiving unit 210 is fixed to the fixed holding member 252. It has become. With such a configuration, the angle of the light receiving optical system 220 can be determined by the angle adjustment table 201, and the determined angle is prevented from changing due to attachment and detachment of the camera.

Here, it should be noted that in the present invention, the optical space optical transmission device does not necessarily have to have an angle adjustment table. For example, it is conceivable to use a tool for adjusting the angle only at the time of installation, perform the angle adjustment of the present invention, fix the position of the light receiving optical system, and then remove the angle adjustment table. Even in this case, the effects of the present invention can be obtained. However, it is preferable to have an angle adjusting base because the man-hours for attaching and removing the angle adjusting base can be reduced.

In this embodiment, a C-mount is used as the detachable portion 251a and the detachable portion 252a. In this way, by using general-purpose technology (a mount part with multiple bayonet claws), it is easy to attach and detach, making it easier to attach a commercially available camera, avoiding the risk of high costs and difficulty in procurement. .

In this embodiment, the camera device is attached only when the spatial light transmission device 2000 is installed, and once the setting of the optical axis direction is completed and the communication state is established, the camera device is always connected. does not require Such a configuration has the effect of reducing the cost of the spatial optical transmission device.

In this embodiment, when a visible light camera is attached, the exchangeable holding member 251 can be removed from the fixed holding member 252 together with the communication light receiving unit 210 and the position detection sensor 232 which is part of the received light detection unit. there is By adopting such a configuration, it is possible to obtain the effect of improving the attachment/detachment workability of the replaceable holding member 251 as compared with the configuration in which only the communication light receiving section 210 is replaced. In addition, since the relative positions of the communication light receiving unit 210 and the position detection sensor 232 are ensured, there is an effect of avoiding the adverse effect of deviation in the direction perpendicular to the optical axis due to attachment and detachment of the communication light receiving unit 210 described above. .

In this embodiment, there is a possibility that the position of the communication light receiving section 210 is slightly shifted every time the communication light receiving section 210 is attached to or detached from the fixed holding member 252 . The shift in the optical axis direction is detected as divergence of the communication light from the spatial light transmission device 2000 when the direction of the communication light is reversed, and is corrected by the focusing mechanism of the light receiving optical system 220 . In other words, the focusing mechanism has the effect of correcting the shift.

In this embodiment, there is a possibility that the position of the communication light receiving section 210 is slightly shifted every time the communication light receiving section 210 is attached to or detached from the fixed holding member 252 . A deviation in the direction perpendicular to the optical axis is detected as an angular deviation of the communication light and corrected by the image blur correction mechanism of the light receiving optical system 220 . In other words, the effect of correcting the shift is obtained by the image blur correction mechanism.

In this embodiment, by reducing the chromatic aberration in the visible light region from the communication wavelength (1540 to 1560 nm) of the light receiving optical system 220, it is possible to adjust the optical axis by visual recognition with a commercially available visible light camera, thereby improving workability. are improving. Also, in order to reduce chromatic aberration over a wide range from infrared wavelengths to visible light wavelengths, the optical system has a reflecting surface. If a refractive system were to be used, the number of lenses would increase.

Up to this point, the spatial optical transmission device 2000 on the receiving side has been mainly discussed for the purpose of explanation. The same is true for In particular, it should be noted that both devices have a transmitted light detector and a received light detector, although only one side is shown. In this embodiment, the reflective prism and the transmissive wedge prism are installed while being rotated by 90° around the optical axis (in FIGS. 2(a) and 3(a), the direction is toward the back of the page). .

In this embodiment, the light emitting optical system and the light receiving optical system of the spatial light transmission device have the same optical axis. It doesn't matter if
Here, the "optical axis" discussed in the present invention means the central optical path of the communication light beam emitted from the emitting means and passing through the light projecting optical system, and the light receiving means passing through the light receiving optical system. It refers to the central optical path of the luminous flux of the communication light heading. Note that the definition is different from the optical axis of a general coaxial optical system.
In this embodiment, for the sake of clarity, a mode is assumed in which the emitting means exists on the optical axis of the coaxial light projecting optical system, and the light receiving means exists on the optical axis of the coaxial light receiving optical system. I was explaining. However, in cases such as when there are no emitting means and light receiving means on the optical axes of the light projecting optical system and the light receiving optical system, communication cannot be established even if the optical axes of a general coaxial optical system are aligned. Further, when the light projecting optical system and the light receiving optical system are decentered optical systems, it is difficult to clearly define the "optical axis". It should be appreciated that the definition of "optical axis" is different for the above reasons.

In this embodiment, the communication light emitted from the optical fiber is received by the optical fiber, but the present invention is not limited to this. For example, the communication light emitted from the semiconductor laser may be received by the sensor.

In this embodiment, the light-receiving unit is configured only with an optical fiber, and the camera device for adjustment is configured with only a sensor, but they are not limited to this, and each may have a lens. For example, a fiber with a collimator may be used as the receiver, and a camera with a lens may be used as the camera for adjustment.

In this embodiment, the distance from the attachment/detachment portion 252a to the sensor surface of the camera device for adjustment and the distance from the attachment/detachment portion 252a to the tip of the fiber of the communication light receiving portion 210 are the same, but the present invention is not limited to this. , it does not matter if it is off.

In this embodiment, the angle of view of the communication light receiving unit 210 is matched with the central angle of view of the sensor of the camera device for adjustment, but the angle of view is not limited to this as long as it exists on the sensor surface. .

In the present embodiment, adjustment was performed using a visible light camera device, but the present invention is not limited to this. (wavelengths within the range of ). Adjustment with a camera device for visible light wavelengths has the advantage of being easy to recognize because it corresponds to visual observation. On the other hand, a camera device for wavelengths close to communication light has the advantage of easily reducing chromatic aberration in the design of the light receiving optical system 220 .

Here, in the present embodiment, part of the communication light emitted from the communication light emitting section 110 is used for detection, but the present invention is not limited to this. For example, a dedicated detection light may be used, for example, a light having a different wavelength from that of the communication light may be incident from the other end (not shown) of the optical fiber of the communication light emitting section 110 and used as the detection light.

In this embodiment, an APS-C size sensor (imaging device) is used. The larger the sensor size, the wider the field of view, which is advantageous for adjustment. However, the invention is not limited to this.

100 light projection unit 110 communication light emission unit (emission means)
120 projection optical system 121, 122, 123 lens (projection optical system)
124 secondary mirror (projection optical system)
125 primary mirror (light projection optical system)
200 light receiving section 210 communication light receiving section (light receiving means)
220 light receiving optical system 221, 222, 223 lens (light receiving optical system)
224 secondary mirror (light receiving optical system)
225 primary mirror (light receiving optical system)
251 replaceable holding member (second holding member)
252 fixed holding member (first holding member)
1000, 2000 Space optical transmission device (optical transmission device)

Claims (12)

An optical transmission device for performing optical communication between a light projecting section including emitting means for emitting communication light and a light projecting optical system, and a light receiving section including a light receiving optical system and light receiving means for receiving the communication light. There is
An optical transmission device comprising: a first holding member that holds the light receiving optical system; and a second holding member that holds the light receiving means and is detachably fixed to the first holding member. . 2. The optical transmission device according to claim 1, wherein said first holding member is coupled to an angle adjustment section for adjusting the orientation of said light receiving optical system. 3. The optical transmission device according to claim 1, wherein said first and second holding members are connected to each other by a mount portion having a bayonet claw portion. 4. The optical transmission device according to claim 1, wherein said second holding member has detection means for detecting the direction and divergence of said communication light. 5. The optical transmission device according to claim 1, wherein said light receiving optical system has a focusing mechanism. 6. The optical transmission device according to claim 1, wherein the light receiving optical system has an image blur correction mechanism that moves an optical element to reduce image blur. 7. The optical transmission device according to claim 1, wherein said light receiving optical system has a reflecting curved surface. 8. The optical transmission device according to claim 1, wherein said emitting means and said receiving means are composed of optical fibers. 9. The optical transmission device according to any one of claims 1 to 8, wherein said optical transmission device does not have a sensor for acquiring an image. In an optical transmission device in which communication light is emitted from a light projecting part and received by a light receiving part including a light receiving optical system and light receiving means that are detachably connected to each other and optical communication is performed, the light receiving optical system for the light projecting part An orientation adjustment method comprising:
mounting an image acquisition means on the light receiving optical system instead of the light receiving unit;
adjusting the orientation of the light receiving optical system based on the image acquired by the image acquisition means;
removing the image acquisition means from the light receiving unit and attaching the light receiving unit to the light receiving unit;
A method for adjusting an optical transmission device, characterized by: 11. The method for adjusting an optical transmission device according to claim 10, wherein said image acquiring means acquires an image of visible light. 11. The method for adjusting an optical transmission device according to claim 10, wherein said image acquiring means acquires an image of light having a wavelength within a range of ±200 nm with respect to the wavelength of said communication light.

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