JPH10239527A - Diffused light reconverging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit diffused light and converge it again at a transmitted place by fitting a non-image-focusing optical element using an eccentrically rotating parabolic mirror constituted by rotating a part of a parabola around a rotation axis shifted by a light receiving allowable angle from the axis of the parabola, to the outlet end of an optical fiber. SOLUTION: In case of being applied to a solar furnace, for instance, the inlet end of an optical fiber 5 is disposed in the focus position of a converging mirror such as a concave mirror for converging sunlight, and a non-image- focusing optical element 6 composed of an eccentric rotating parabolic mirror 7 is fitted to the outlet end of the optical fiber 5. The eccentric rotating parabolic mirror 7 is constituted by rotating a part of a parabola around a rotation axis shifted by a light receiving allowable angle from the axis of the parabola. Sunlight (diffused light) 21 of high density transmitted by the optical fiber 5 is converged at an outlet part 20 using the non-image-focusing optical element 6 making use of the eccentric rotating parabolic mirror 7, and an object arranged at the outlet part 20 of the non-image-focusing optical element 6 is fused by the converged sunlight 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffused light refocusing device, and more particularly to a diffused light refocusing device capable of transmitting diffused light and refocusing at a transmission destination. It is about.

[0002]

2. Description of the Related Art Conventionally, as a device for collecting parallel rays, a convex lens, a concave mirror and the like are known. However, very few devices that can collect diffused light are currently known.

[0003] Therefore, transmission of diffused light and collection and use of the diffused light at a transmission destination have hardly been performed.

[0004]

For example, sunlight is collected by a concave mirror in space or the like, an object is placed at the focal position of the concave mirror, and the object is melted by utilizing the high heat of the high-density sunlight obtained at the focal position. Although a solar furnace is considered,
In such a solar furnace, it is necessary to track the concave mirror to the sun, and at that time, the focal position of the concave mirror will move, so the problem that the position of the object must be moved according to the movement of the focal position. is there.

Therefore, if the high-density sunlight obtained at the focal position of the concave mirror can be effectively transmitted to another place,
The concave mirror and the object can be separated and arranged, and the development of a more practical solar furnace can be expected.

However, the high-density sunlight obtained at the focal position of the solar furnace is diffused light, and the sunlight is diffused when transmitted. Therefore, high heat cannot be obtained simply by transmission. In order to avoid this, it is necessary to condense the diffused sunlight again at the transmission destination.

However, as described above, since there was no device capable of effectively condensing diffused light, a highly practical solar furnace in which a concave mirror and an object were separately arranged could not be developed.

[0008] In addition to the above, the technique of transmitting diffused light and collecting light again at the transmission destination can be applied to various devices such as a heater, a regenerator, and other high-temperature heat devices.
Technically there is a growing demand.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a diffused light refocusing device which can transmit diffused light and collect light again at a transmission destination.

[0010]

According to the present invention, a part of the parabola 10 is rotated at the exit end of the optical fiber 5 around a rotation axis 18 which is shifted from the axis of the parabola 10 by an allowable light receiving angle θ. The present invention relates to a diffused light refocusing apparatus characterized in that a non-imaging optical element 6 using a decentered rotary parabolic mirror 7 is mounted.

In this case, a truncated cone 22 may be formed at the exit 20 of the non-imaging optical element 6.

According to the above means, the following effects can be obtained.

The diffused light transmitted by the optical fiber 5 is used to convert a part of the parabola 10 into a permissible light receiving angle θ with respect to the axis of the parabola 10.
The light is condensed at the transmission destination by using the non-imaging optical element 6 using the off-axis rotating parabolic mirror 7 that is formed by rotating around the rotation axis 18 that is shifted only by an angle.

In this case, by forming the truncated cone portion 22 at the exit portion 20 of the non-imaging optical element 6, the maximum emission angle can be reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a first embodiment of the present invention.

In this embodiment, a case where the present invention is applied to a solar furnace will be described as an example.

A light-collecting device 3 is constructed by providing a light-collecting mirror 2 such as a concave mirror that collects sunlight 1.

An entrance end of the optical fiber 5 is disposed at the position of the focal point 4 of the condenser mirror 2, the optical fiber 5 is guided to the outside, and the non-imaging optical element 6 is disposed at the exit end of the optical fiber 5.
(Compound Parabolic Consence
(referred to as CPC for short).

Here, the condensing device 3 can track the sun by providing a not-shown tracking device or the like to the converging mirror 2. The condensing mirror 2 is not limited to a single concave mirror, but may be configured to have a similar function by combining a plurality of reflecting mirrors. it can.

The optical fiber 5 is used by bundling a large number thereof, and the entrance end thereof is held at the position of the focal point 4 of the condenser mirror 2 by a holding member (not shown) or the like.

The non-imaging optical element 6 is constituted by a special rotating parabolic mirror 7 (hereinafter, referred to as an off-axis rotating parabolic mirror 7). Incidentally, the non-imaging optical element 6 is provided with a cooling jacket 9 for cooling with the cooling liquid 8 on the outer peripheral portion.

The off-axis rotating parabolic mirror 7 is as follows.

First, as shown in FIG. 3, the refractive index of the material constituting the off-axis rotating parabolic mirror 7 (for example, the refractive index of glass if it is made of glass, and the hollow structure as shown in FIG. 2) If so, a predetermined parabola 10 is drawn based on the refractive index of air. Here, the predetermined parabola 10 means that light 12 to 14 incident from a direction parallel to the axis 11 is a parabola 10.
It is a parabola that is reflected above and condensed at one point on the axis 11 (focal point A).

Once the parabola 10 has been drawn, the allowable light receiving angle θ, which is the maximum incident angle, is set. The light receiving allowable angle θ
Is determined in relation to the light condensing device 3, and FIG.
In this case, it is represented by an angle formed with respect to a rotating shaft 18 described later.

Then, from the position of the focal point A of the parabola 10,
A straight line 15 having an angle (2θ) twice as large as the light-receiving allowable angle θ with respect to the axis 11 is drawn, and the intersection of the straight line 15 and the parabola 10 is defined as a point B. From the position of the focal point A, a straight line 16 having an angle equal to the light-receiving allowable angle θ with respect to the axis 11 is drawn, a straight line 17 orthogonal to the straight line 16 is drawn from the focal point A, and the intersection of the straight line 17 and the parabola 10 is pointed. C.

Further, a line perpendicular to the straight line 17 is drawn from the bisecting point D between the focal point A and the point C, and this line is used as a rotation axis 18.
The rotation of the parabola BC constitutes the off-axis rotating parabolic mirror 7. The position at which the point B is rotated by 180 degrees about the rotation axis 18 is defined as a point E.

Reference numeral 19 denotes an inlet of the off-axis rotating parabolic mirror 7, 20 denotes an outlet of the off-axis rotating parabolic mirror 7, and 21 denotes sunlight as diffused light.

Next, the operation will be described.

In the present invention, the sunlight 1 is condensed by using a condensing device 3 having a converging mirror 2 such as a concave mirror.
The high-density sunlight 21 (diffused light) collected at the position of the focal point 4 of the condenser mirror 2 is guided to the outside by using the optical fiber 5 having the entrance end disposed at the position of the focal point 4.

Then, the high-density sunlight 21 (diffused light) guided to the outside by the optical fiber 5 is transmitted to the non-imaging optical element 6 (Compound) attached to the exit end of the optical fiber 5.
The light is condensed at the exit portion 20 of the non-imaging optical element 6 using a dParabolic Concentrator (CPC for short).

Then, in the solar furnace, the concentrated sunlight 2
By 1, an object (not shown) arranged at the exit portion 20 of the non-imaging optical element 6 is melted.

This makes it possible to develop a highly practical solar furnace in which the condenser mirror 2 such as a concave mirror and the object to be melted are separated from each other.

Here, the off-axis rotating parabolic mirror 7 constituting the non-imaging optical element 6 focuses diffused light in the following manner.

That is, for example, when viewed from the parabolic portion BC, the off-axis rotating parabolic mirror 7 is incident on the parabolic portion BC from a direction parallel to the axis 11 of the parabola 10 (that is, with respect to the rotating shaft 18). The light 12-14 incident at an angle equal to the light-receiving allowable angle θ) is reflected once on the parabolic portion BC due to the nature of the parabola 10, and is collected at the focal point A.
Then it is spread.

Light incident toward the parabolic portion BC at an angle smaller than the light-receiving allowable angle θ is incident on the parabolic portion BC.
Is reflected once on the parabola BC and the line segment A
C, or pass between the line segments AC without being reflected once on the parabolic portion BC.

The light incident on the parabolic portion BC at an angle larger than the permissible light receiving angle θ is reflected at least once on the parabolic portion BC due to the nature of the parabola 10, and is returned to the segment BE. However, the light-receiving allowable angle θ is a value determined based on the relationship with the light-collecting device 3, so that light is not incident at an angle larger than the light-receiving allowable angle θ. The non-imaging optical element 6 and the condensing device 3 are designed so that the light is not returned to the side.

Therefore, looking at the parabolic portion BC,
The light incident toward the parabolic portion BC is all the line segments A
Light is condensed so as to pass between C.

Looking at the parabola EA obtained by rotating the parabola BC by 180 degrees around the rotation axis 18 which is the perpendicular bisector of the line AC, the point C is now the focal point of the parabola EA. Therefore, all the light incident toward the parabolic portion EA is condensed so as to pass between the line segments AC, as described above.

That is, with respect to the parabolic portion EA, light incident on the parabolic portion EA from a direction parallel to the straight line 15 inclined by the light receiving allowable angle θ with respect to the rotation axis 18 is incident on the parabolic portion EA due to the nature of the parabola. Is reflected once, is collected at a point C (the focal point of the parabolic portion EA), and is thereafter diffused.

The light incident toward the parabola EA at an angle smaller than the light-receiving allowable angle θ is reflected once on the parabola EA and passes between the line segments AC due to the nature of the parabola. Or, it passes between the line segments AC without being reflected once on the parabolic portion EA.

Then, the light incident on the parabolic portion EA at an angle larger than the permissible light receiving angle θ is given by
The light is reflected at least once on the parabolic portion EA and returned to the line segment BE side. The allowable light receiving angle θ is a value determined based on the relationship with the light collecting device 3 and is larger than the allowable light receiving angle θ. So that no light is incident on the line segment B
The non-imaging optical element 6 and the condensing device 3 are designed so that light does not return to the E side.

Therefore, looking at the parabolic portion EA,
All light incident toward the parabolic portion EA is a line segment A
It can be seen that light is condensed so as to pass between C.

Further, the off-axis rotating parabolic mirror 7 formed by rotating the parabolic portion BC about a rotation axis 18 which is a perpendicular bisector of the line segment AC has a focal point A about the rotation axis 18. For the same reason as above, the light incident at the light-receiving allowable angle θ is reflected once by the off-axis rotating parabolic mirror 7 and collected at the outlet 20 for the same reason as described above. It will be lighted and then diffused.

The light incident at an angle smaller than the light-receiving allowable angle θ is reflected once on the off-axis rotating parabolic mirror 7 and passes through the outlet 20 or on the off-axis rotating paraboloid. The light passes through the exit portion 20 without being reflected once on the mirror 7.

The light incident at an angle larger than the allowable light receiving angle θ is reflected once on the off-axis rotating parabolic mirror 7 and returned to the entrance 19 side. This is a value determined based on the relationship with the light condensing device 3, so that the light is not incident at an angle larger than the allowable light receiving angle θ, and therefore, is shifted toward the off-axis rotation parabolic mirror 7. The non-imaging optical element 6 and the light condensing device 3 are designed so that the light is not returned.

Therefore, the off-axis rotating parabolic mirror 7 is
After all the incident light is reflected once or zero times, the line segment A
It functions to allow C to pass through the outlet 20 having a diameter and then diffuse.

As described above, the exit 2 of the non-imaging optical element 6
At the position of 0, the sunlight 21 as the diffused light can be collected.

Here, the light collection rate of the non-imaging optical element 6 is the area ratio between the entrance 19 having the line segment BE in diameter and the exit 20 having the line segment AC in diameter.

When the light 12 is reflected at the position of the point C on the parabola BC, it is diffused through the focal point A in the extension direction of the line segment CA, and conversely, the light incident along the straight line 15 Is reflected at the position of the point A on the parabolic portion EA, and is diffused in the direction of extension of the line segment AC through the point C. Therefore, at the exit portion 20 of the off-axis rotating parabolic mirror 7, The maximum emission angle φ of the sunlight 21 is 90 degrees with respect to the rotation axis 18.

FIG. 4 and FIG. 5 show a second embodiment of the present invention.
The truncated cone portion 22 is formed so that the maximum emission angle φ of the sunlight 21 that is diffused light can be reduced to an angle smaller than 90 degrees.

That is, as shown in FIG. 5, the light incident on the off-axis rotation parabolic mirror 7 at the allowable light receiving angle θ is the light of the corresponding focal point F at the exit 20 of the off-axis rotation parabolic mirror 7. The light is always condensed at a position, and the output angle increases as the light is reflected at a position closer to the exit portion 20 of the off-axis rotating parabolic mirror 7. 7 is searched for a point G at which a desired emission angle (for example, 70 degrees) is obtained.
The portion from that point up to the exit portion 20 is replaced by a truncated cone portion 22 having a tangent to a parabola as a generatrix.

By doing so, in the truncated cone portion 22, the emission angle becomes the same value as the emission angle at the point G everywhere, so that the maximum emission angle φ of the off-axis rotating parabolic mirror 7 is set to G can be made equal to the emission angle.

Then, the sunlight 2 which is the diffused light is
1 can be reduced to an angle smaller than 90 degrees, thereby preventing the sunlight 21 emitted from the exit portion 20 of the off-axis rotating parabolic mirror 7 from being immediately diffused. For example, when applied to a solar furnace, it becomes possible to displace the object to be melted and dispose it at a position slightly away from the outlet 20 of the rotating parabolic mirror 7. .

In this case, since the diameter of the exit portion 20 becomes slightly larger, the light condensing rate of the non-imaging optical element 6 is slightly reduced.

Except for the above, the configuration is the same as that of the above embodiment, and the same operation and effect can be obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the scope of the present invention.

[0058]

As described above, according to the diffused light refocusing device of the present invention, there is an excellent effect that the diffused light can be transmitted and collected again at the transmission destination.

[Brief description of the drawings]

FIG. 1 is an overall schematic side view of a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a diagram for explaining the shape of a parabolic mirror with off-axis rotation;

FIG. 4 is a view similar to FIG. 2 according to a second embodiment of the present invention.

FIG. 5 is a view for explaining the shape of the truncated cone portion.

[Explanation of symbols]

 Reference Signs List 5 optical fiber 6 non-imaging optical element 7 off-axis rotating parabolic mirror 20 exit 22 frustoconical part

Claims (2)

[Claims] At the outlet end of an optical fiber, a part of a parabola (10) is turned around a rotation axis (18) which is shifted from the axis of the parabola (10) by an allowable light receiving angle (θ). A diffused light refocusing apparatus characterized in that a non-imaging optical element (6) using an off-axis rotating parabolic mirror (7) formed by rotation is mounted instead. 2. An exit part (20) of the non-imaging optical element (6).
The diffused light refocusing device according to claim 1, wherein a frustoconical portion (22) is formed on the diffused light.