JP3601845B2 - Concentrator - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a light collecting device used in the field of information communication using light in space as a transmission medium. In addition, the present invention relates to a light-collecting device that can be used as an optical lens system such as an optical sensor.
[0002]
[Prior art]
Conventionally, as a technique in such a field, for example, there has been the following technique.
[0003]
FIG. 11 is a diagram showing an example of the configuration of an optical receiver system in such a conventional optical space communication. FIG. 11A shows an optical receiver in which the received light is directly applied to the light receiving surface of the semiconductor light receiving element without using a lens. 11B is a configuration diagram of an optical receiver system in which a normal lens for condensing is provided in front of a light receiving surface of a semiconductor light receiving element, and FIG. 11C is a light receiving area of the lens. FIG. 2 is a configuration diagram of an optical receiver system when the focal length is large and the focal length is short.
[0004]
First, in the case of FIG. 11 (a), the light receiving area as the receiver is the same as the area of the light receiving surface 2 of the semiconductor light receiving element 1, the light quantity incident on the semiconductor light receiving element 1 is small, and optical communication capable of communication is performed. Distance is limited to short distances.
[0005]
In addition, in order to realize long-distance optical space communication, it is necessary to efficiently condense light from a wider area using a lens or the like, and to strike the light receiving surface of the semiconductor light receiving element.
[0006]
Therefore, the case of FIG. 11B is an example in which the single lens 3 is provided in front of the light receiving surface 2 of the semiconductor light receiving element 1. In order to converge light with high efficiency and enable light transmission at a long distance, it is necessary to increase the light receiving area of the single lens 3, but the focal length of the single lens 3 becomes longer, and the The angular range becomes narrow.
[0007]
In conventional optical space communication where the position of both the transmitter and the receiver is fixed, a narrow viewing angle does not pose a significant problem.However, in the space optical communication method for mobile objects such as automobiles, the relative position of the communication target is small. Due to the fluctuation of the optical lens system, a relatively wide viewing angle range is required for the optical lens system used.
[0008]
Therefore, in order to increase the light receiving area of the lens and shorten the focal length, the lens 4 needs to have a multi-group and multi-lens configuration as shown in FIG. Therefore, both the size and the weight are increased, and the cost is increased.
[0009]
[Problems to be solved by the invention]
As described above, in the conventional optical space communication method for mobile objects such as automobiles described above, the fixed position is fixed due to the relative position of the mobile object and the mobile object to be communicated or the relative position of the mobile object and the fixed station fluctuating. Compared to communication, a relatively wide viewing angle range of receiver directivity is required. At the same time, in order to prevent unnecessary extraneous noise light and ensure high communication quality, it is necessary to limit reception within a finite directional angle range.
[0010]
In the optical space communication system as described above, the light receiving surface of the semiconductor light receiving element must have a small area because of the large amount of information and the need for communication at a high code transmission rate.
[0011]
Therefore, in order to realize optical space communication at a long distance, it is necessary to efficiently condense light on the light receiving surface of the semiconductor light receiving element.
[0012]
An optical lens system that satisfies the above requirements cannot be technically satisfactory with the single lens described above, and such a lens system requires a multi-group, multi-element configuration, and is large in size and weight. In addition, there is a problem that the cost increases.
[0013]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a compact, lightweight, and low-cost light-collecting device that eliminates the above-described problems and efficiently condenses signal light from within a predetermined viewing angle range.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides, in a light-collecting device, two pairs of an incident end face, an exit end face having a smaller area than the incident end face, and a pair of the incident end face and the exit end face facing each other. A light collecting device having four side surfaces, each of the four side surfaces being opposite to each other, and the incident end surface having a wide-angle directivity in another direction while limiting the directivity in one direction. In order to provide a shape, a shape having a curved surface in a direction corresponding to a pair of side surfaces among the four side surfaces is adopted.
[0015]
[Action]
According to the present invention, the incident light from the incident end face is guided to the output end face of the main body by utilizing the optical reflection on the tapered surface of the main body made of a pyramid or a cone made of an optical lens material.
[0016]
Also, in addition to focusing by the optical path trajectory in the main body, by changing the shape and taper angle of the incident end face of the main body, the directional characteristics of the light collecting device as the light guide tube and the coupling with the light receiving element are changed. The property can be set to a given property.
[0017]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a perspective view of a light collecting device (light guide tube) according to a first embodiment of the present invention.
[0019]
As shown in FIG. 1, a light-collecting device (light guide tube) 10 composed of a transparent quadrangular pyramid main body 11 and having an opening surface (incident end surface) 12 and an emitting end surface 13 as planes is configured.
[0020]
The light collecting device 10 is made of an optical glass or an organic optical material, and each surface is finished to an optical mirror surface. (This is not an optical mirror reflection surface, but a process for eliminating surface irregularities.)
In particular, in the case of using an organic optical material, a structure having good shape accuracy and surface finish on each surface can be mass-produced at low cost by a casting method using a mold.
[0021]
The tapered surface 14 forms an optical mirror reflection surface. This is manufactured by a vapor deposition method of a metal thin film such as aluminum or a silver mirror reflection method in the case of a normal mirror manufacturing.
[0022]
FIG. 2 is a perspective view of a light collecting device (light guide tube) according to a second embodiment of the present invention.
[0023]
As shown in this figure, a light-collecting device (light guide tube) comprising a transparent quadrangular pyramid main body 21, an opening surface 22 having a semi-cylindrical shape having a curved surface 22 a only in the horizontal direction, and an emission end surface 23 having a flat surface. 20. The tapered surface 24 forms an optical mirror reflection surface.
[0024]
FIG. 3 is a perspective view of a light collector (light guide tube) showing a third embodiment of the present invention.
[0025]
As shown in this figure, a light-condensing device (light guide tube) comprising a transparent quadrangular pyramid body 31, an opening surface 32 having a semicylindrical shape having a curved surface 32 a only in a vertical direction, and an emission end surface 33 having a flat surface. 30. The tapered surface 34 forms an optical mirror reflection surface.
[0026]
The light collectors (light guide tubes) 20 and 30 shown in FIG. 2 or FIG. 3 limit the directional angle in either the horizontal or vertical direction in which the influence of extraneous noise light is considered, and This is an effective shape when giving wide-angle directivity. For example, when optical space communication is performed between moving objects such as automobiles, a directivity angle is provided only in a horizontal direction, and a directivity angle in a vertical direction in which signal light cannot be obtained and extraneous noise light from the sun can be considered. It is suitable for the case.
[0027]
FIG. 4 is a perspective view of a light collecting device (light guide tube) according to a fourth embodiment of the present invention.
[0028]
As shown in this figure, a light-collecting device (light guide tube) comprising a transparent quadrangular pyramid body 41, having an opening surface 42 with curved surfaces in the vertical and horizontal directions, that is, a spherical surface 42 a and an emission end surface 43 as a plane. ) 40. The tapered surface 44 forms an optical mirror reflection surface.
[0029]
The light collecting device 40 is suitable for limiting both the horizontal and vertical directional angles where the influence of extraneous noise light is considered.
[0030]
FIG. 5 is a configuration diagram of a light collecting device (light guide tube) showing a fifth embodiment of the present invention. FIG. 5 (a) is a side view of the light collecting device (light guide tube), and FIG. FIG. 3 is a front view of the light collecting device (light guide tube).
[0031]
As shown in this figure, a condensing device (light guide tube) 50 composed of a transparent conical body 51, an opening surface 52 having a spherical surface 52a, and an emission end surface 53 having a flat surface is formed. The tapered surface 54 forms an optical mirror reflecting surface.
[0032]
This has the advantage that when the light guide tube is manufactured by machining, this shape is relatively easy to process. This is suitable when external noise light from a certain direction cannot be considered and the same directional characteristics are set in all directions.
[0033]
Further, in the case of the light-collecting device based on the transparent quadrangular pyramid shown in FIGS. 1 to 4, in order to set the directional characteristics in the horizontal direction and the vertical direction to predetermined values, the horizontal and vertical directions of the tapered surface are respectively set. The selection of the vertical taper angle, the selection of the aspect ratio of the opening face and the quadrilateral of the emission end face, and the selection of whether the opening face is spherical or semi-cylindrical are possible.
[0034]
FIG. 6 is an explanatory view for explaining the basic principle of the light collecting device (light guide tube) of the present invention, and FIG. 7 is a diagram showing a structural model of the light collecting device (light guide tube) of the present invention.
[0035]
In the light collecting device having the tapered surface of the embodiment of FIGS. 1 to 5 in the horizontal plane including the central axis A, the incident light is given a deflection angle with respect to the horizontal central axis A in the light collecting device. It shows an optical path trajectory.
[0036]
In the case of FIG. 6A, light incident from the opening surface 62 of the main body 61 of the light collecting device 60 passes through the inside of the light collecting device 60 without being reflected by the tapered surface 64, and is emitted from the emission end surface 63. This corresponds to the case of incident light that is close to the central axis A and has a relatively small deflection angle with respect to the central axis A.
[0037]
In the case of FIG. 6B and FIG. 6C, the light incident from the opening surface 62 is reflected from the tapered surface 64 once or twice in the light-collecting device, and then emitted from the emission end surface 63. In this case, the number of times of reflection on the tapered surface 64 increases as the incident position of the incident light is farther from the central axis or as the deflection angle is larger.
[0038]
In the above-mentioned optical path trajectory, assuming that the deviation angle with respect to the central axis of the tapered surface 64 is θ _g , the absolute value of the optical path in the light condensing device with respect to the central axis increases by 2θ _g every time reflection proceeds by the tapered surface. . Further, the aperture surface and the emission end surface are interfaces between the refractive index of the optical material constituting the light guide tube and the refractive index of the atmosphere. The refractive relationship between the incident light and the outgoing light outside the device is determined.
[0039]
As shown in FIG. 7, in a horizontal plane containing the central axis A of the body 71 of the condenser 70, the horizontal half-width of the opening surface 72, that is, the incident position of the incident light incident end face radius D _a, the opening surface 72 the _{D in,} as _in the polarization angle of the incident light theta with respect to the central axis a, the relation between _D in / _{D a} and theta _in passing through the condenser 70, shown in FIGS.
[0040]
In FIG. 7, the exit end face 73, 74 taper surface, _{R g} is spherical entrance end face radius, theta _r is the opening angle, theta _g taper angle, _{D b} is emitting facet radius, theta _out the central axis A Declination of the emitted light with respect to
[0041]
FIG. 8A is a characteristic diagram of the deviation angle θ _in of the incident light with respect to the central axis A and the ratio Pr at which the incident light is emitted. The horizontal axis represents θ _in (degree), and the vertical axis represents the incident light. Indicates the ratio Pr. FIG. 8B is a directional characteristic diagram of the emission end face, and shows a case where D _a / D _b = 10.0, R _g / D _a = 3.0, and θ _g = 15 ° as conditions. .
[0042]
FIG. 9A is the same as FIG. 8A, and is a characteristic diagram of the deviation angle θ _in of the incident light with respect to the central axis A and the ratio Pr of the incident light to be emitted, and the horizontal axis represents θ _in ( Degree), and the vertical axis indicates the ratio Pr from which the incident light is emitted. FIG. 9B is a directional characteristic diagram of the emission end face, and shows a case where D _a / D _b = 10.0, R _g / D _a = 2.5, and θ _g = 15 ° as conditions. .
[0043]
As is apparent from these figures, the characteristic light-collecting effect of the light-collecting device (light guide tube) of the present invention is shown.
[0044]
FIG. 10 is a view showing an example of an optical path trajectory in the light collecting device (light guide tube) of the present invention viewed from the opening surface side, and FIG. 10 (a) is based on a quadrangular pyramid. FIG. 10B shows a case based on a cone.
[0045]
In the drawing, the incident light from the point P _{in on the} aperture surface passes through the points R ₁ , R ₂ ,... And reflection on the tapered surface in the light condensing device, and is emitted from the point P _{out on the} exit end surface. Become.
[0046]
In this case, as shown in the figure, the optical path in the light collector travels while rotating. However, the basic items of the light-collecting characteristics described with reference to FIGS. 6 and 7 are universal.
[0047]
It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.
[0048]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) A collection that can increase the effective light receiving area of a light receiving element in a receiver used for high-speed code transmission communication and have a relatively wide-angle directivity required for optical communication between moving objects. The optical device can be realized with a small size and a low cost.
(2) The directivity characteristics in the horizontal and vertical directions can be easily set to arbitrary values, respectively, in accordance with the application form, so that it is possible to provide an extremely sharp cutoff characteristic in a directivity range only in a certain direction. There is an advantage that various kinds of external noise light harmful to optical communication via reflection from surrounding buildings and the like are blocked, and a high quality communication state can be secured.
(3) Similarly, when used for an optical sensor, there is an advantage that a malfunction of the sensor can be prevented by blocking extraneous noise light and obtaining only light in a required directional angle range.
[Brief description of the drawings]
FIG. 1 is a perspective view of a light collecting device (light guide tube) showing a first embodiment of the present invention.
FIG. 2 is a perspective view of a light collector (light guide tube) showing a second embodiment of the present invention.
FIG. 3 is a perspective view of a light collector (light guide tube) showing a third embodiment of the present invention.
FIG. 4 is a perspective view of a light collector (light guide tube) showing a fourth embodiment of the present invention.
FIG. 5 is a perspective view of a light collector (light guide tube) showing a fifth embodiment of the present invention.
FIG. 6 is an explanatory diagram for explaining a basic principle of a light collecting device (light guide tube) of the present invention.
FIG. 7 is a diagram showing a structural model of a light collecting device (light guide tube) of the present invention.
FIG. 8 is a diagram (part 1) showing the light-collecting characteristics of the light-collecting device (light guide tube) of the present invention.
FIG. 9 is a diagram (part 2) illustrating the light-collecting characteristics of the light-collecting device (light guide tube) of the present invention.
FIG. 10 is a diagram illustrating an example of an optical path trajectory viewed from the opening surface side of the light collecting device (light guide tube) of the present invention.
FIG. 11 is a configuration example diagram of an optical receiver system in conventional optical space communication.
[Explanation of symbols]
10, 20, 30, 40, 50, 60, 70 Light collecting device (light guide tube)
11, 21, 31, 41, 51, 61, 71 Main body 12, 22, 32, 42, 52, 62, 72 Opening surface (incident end surface)
13, 23, 33, 43, 53, 63, 73 Outgoing end surface 14, 24, 34, 44, 54, 64, 74 Tapered surface 22a, 32a Curved surface 42a, 52a Spherical surface

Claims (1)

In a light collecting device used when performing optical communication between moving objects, the light collecting device,
Incident end face,
An output end face having a smaller area than the input end face;
Having four side surfaces consisting of two pairs of surfaces facing each other between the incident end surface and the output end surface,
The four side surfaces are reflection surfaces,
The incident end face has a shape having a curved surface in the horizontal direction among the four side surfaces so as to have a wide-angle directivity in the horizontal direction while limiting the directivity in the vertical direction. Light collecting device.

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