JPH10255525A - Lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system having excellent focusing performance such that no color aberrations and unevenness occur even with a light source of a wide wavelength range or of short wavelengths. SOLUTION: Light from a lamp 10 is focused by reflectors 40, 50 which extend along an ellipse (e) whose foci are located at the luminescent point P and focusing point Q of the lamp 10. The focusing point of a light beam reflected by the center reflector 40 and re-transmitted through a bulb 11 is made to deviate from the focusing point Q by the action of the bulb 11 as a negative lens, but the focusing point Q provided by the reflector 50 and that provided by the reflector 40 are made to almost coincide with each other by moving the reflector 40 a predetermined distance δ from the ellipse (e). Further, the reflecting surface of the reflector 40 is made into an aspherical surface to correct spherical aberrations that occur when the light beam passes through the bulb 11, and an imaging magnification achieved by the reflector 50 at the focusing point Q and that achieved by the composite optical system of the reflector 40 and the bulb 11 are made to almost coincide with each other to prevent brightness unevenness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device for condensing light from a light source lamp at a converging point.

[0002]

2. Description of the Related Art FIG.
This will be described with reference to FIG. FIG. 5A is a schematic diagram illustrating a configuration of an illumination device using a refraction-based imaging optical system that has been conventionally used. A state where light is condensed on a point Q by the system 20 is shown. This optical system is used, for example, when focusing a light beam on a slit of a monochromator or the like. The magnification of the image forming optical system is configured such that a necessary light amount is obtained in consideration of the luminance distribution and light distribution characteristics of the light source lamp.

When a wide wavelength range is required for illumination light,
When such a refraction system is used, it becomes difficult to correct chromatic aberration, and it becomes difficult to obtain desired imaging performance in all wavelength ranges. Further, even if the wavelength range of the illumination light is narrow, if the wavelength is short, for example, 200 nm or 300 nm, usable glass materials are limited, so that it becomes difficult to correct chromatic aberration, and similarly, a desired imaging performance can be obtained. difficult.

With respect to the above-mentioned problem of aberration, as shown in FIG. 5B, a reflection optical system has been used as an imaging optical system. Usually, this reflecting optical system has an elliptical mirror, that is, FIG.
(B) using a reflecting mirror 30 constituting a part of the ellipse e;
One of the two focal points of the ellipse e coincides with the bright point P of the light source 10 and the other coincides with the focal point Q.
With such a configuration, chromatic aberration does not occur even when the wavelength range of the illumination light is wide or short, and good imaging performance can be obtained.

[0005]

However, FIG. 5 (b)
In the illuminating device shown in (1), there are no problems with light rays passing through the optical paths shown in a to c. However, as shown in (d), the light rays passing through the optical path near the optical axis are reflected by the reflecting mirror 30 and then passed through the lamp bulb of the light source. When re-passing, it is refracted and no longer coincides with the focal point Q, thereby deteriorating the imaging performance. In contrast, FIG.
As shown in FIG. 5C, a reflecting mirror 300 forming a part of an elliptical surface indicated by a two-dot chain line is disposed at a position deviated from the optical axis X, or the reflecting mirror 300 is formed with respect to the X axis in FIG. A so-called off-axis optical system, in which another reflecting mirror 300 'is disposed at a position symmetrical to the above, is used. However, even when this off-axis optical system is used, the following problems are encountered.

That is, the beam spread at a position shifted forward and backward from the focal point Q does not become symmetric with respect to the optical axis X when only the reflecting mirror 300 is provided on one side as shown in FIG. And reflecting mirrors 300 and 300 'in FIG.
When arranged symmetrically with respect to the X-axis, what is called a so-called hollow hole cannot be obtained, and uniform illumination cannot be obtained. It can be improved by using a cone lens for hollow holes, but when a cone lens is used,
As in the case of using a refraction system, the problem of chromatic aberration occurs, and the shape of the lamp house becomes large.

It is an object of the present invention to save installation space,
It is an object of the present invention to provide an illumination device that exhibits excellent light-collecting performance for a light source having a wide wavelength range or a short wavelength.

[0008]

FIG. 1 shows an embodiment of the present invention.
(1) The invention according to claim 1 is a light source 10 having a bulb 11; and at least a central reflecting surface 40a for reflecting light from the light source 10 and condensing the light at a converging point Q. The present invention is applied to a lighting device having a peripheral surface 50a and a peripheral reflecting surface 50a. After being reflected by the central reflecting surface 40a, the light is condensed without re-transmitting through the bulb 11 after being reflected by the peripheral reflecting surface 50a. The above-described object is achieved by determining the surface shape of the central reflecting surface 40a so that the light converging point of the luminous flux coincides with Q. (2) The invention according to claim 2 provides the central reflecting surface 40a.
And the central reflecting surface 40 so that the imaging magnification of the image of the light source 10 formed by the bulb 11 and the imaging magnification of the image of the light source 10 formed only by the peripheral reflecting surface 50a are further matched.
The surface shape of “a” is determined. (3) In the invention described in claim 3, the central reflecting surface 40a and the peripheral reflecting surface 50a form a part of an ellipse e represented by the same shape parameter, and only the position parameter is different. Is what it is. That is, the position of the reflection surface 40a shown in FIG. 1A is moved to the position shown in FIG. 1B along the X-axis direction. (4) According to the invention described in claim 4, the difference δ of the position parameter is determined by the central reflecting surface 40 determined by paraxial theory.
a and the amount of shift between the position of the focal point by the bulb 11 and the position of the focal point by the peripheral reflecting surface 50a. (5) In the invention described in claim 5, the peripheral reflecting surface 50a is an elliptical mirror, and the central reflecting surface 40a is an aspherical mirror. (6) The invention according to claim 6 is characterized in that the central reflecting surface 40a is provided.
The central reflection surface 40a is used to correct the spherical aberration caused by the light reflected by the
The shape of the aspheric mirror is determined. (7) The invention according to claim 7, wherein the central reflecting surface 40a
Is a toric aspheric surface.

In the meantime, in the section of the means for solving the above-mentioned problem which explains the constitution of the present invention, the drawings of the embodiments of the present invention are used in order to make the present invention easy to understand. However, the present invention is not limited to this.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a main part of a lighting device according to an embodiment of the present invention.
Reference numerals 40 and 50 denote reflecting mirrors. In FIG. 1,
The same parts as those in FIG. 5 showing the lighting device according to the related art are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1A, reflecting mirrors 40 and 5
Numeral 0 is arranged so as to form a part of an ellipse e (a two-dot chain line) represented by a predetermined equation with the luminescent point P and the condensing point Q of the light source 10 as focal points. And the reflecting mirror 40 is the reflecting mirror 5
It is configured to be movable in the optical axis X direction in FIG. The broken lines in the figure indicate how light emitted from the luminescent spot P of the light source 10 is reflected by the reflecting surfaces 40a to 50a of the reflecting mirrors 40 and 50, and travels toward the converging point Q.

FIG. 1A shows an example in which the reflecting mirror 40 is arranged at an undesired position in the embodiment of the present invention. In FIG. 1A, broken lines a and b are shown.
When the light beam indicated by is re-transmitted through the bulb 11 of the light source 10, the light path is bent, and is not converged at the converging point Q. This is because the thin cylindrical portion of the bulb 11 acts as a lens having negative power.

FIG. 1B shows the reflection mirror 4 shown in FIG.
0 is shifted by a predetermined distance δ in a direction away from the light source 10 along the direction of the optical axis X. In other words, FIG.
In the equation of the ellipse representing the reflecting surface 40a of the reflecting mirror 40 shown in (b), of the parameters representing the shape and position of the ellipse e, only the position parameter in the optical axis X direction was changed without changing the shape parameter. It has become something. In FIG. 1 (b), the predetermined distance δ is determined so that the light path indicated by the broken lines c and d is bent at the light path when retransmitting through the bulb 11, and then condensed at the converging point Q. I have.
The division position of the reflecting mirrors 40 and 50 will be described. A point (R, R in the figure) that passes through the light condensing point Q and intersects an extension of a tangent line (H, I in FIG.
S) is a division position. By determining the dividing position of the reflecting mirror in this way, the illumination light reflected by the reflecting mirror 50 does not re-transmit through the bulb 11, and is condensed on the converging point Q without generating aberration, and the position correction can be performed. The illuminating light reflected by the reflecting mirror 40 is transmitted through the bulb 11 again and is condensed at the converging point Q.

As described above, the reflecting mirror constituting a part of the ellipse e is divided into a plurality of parts, and the arrangement position of the reflecting mirror at the center is shifted, so that the light reflected by these reflecting mirrors becomes The light reflected by the central mirror and not transmitted again through the bulb 11 and the light reflected by the central mirror and reflected by the bulb 11
Is condensed on the same light condensing point Q, and good imaging performance can be obtained. However, when trying to collect light more strictly, the light reflected by the reflection surface 40a is
It is necessary to correct the spherical aberration that occurs when the light 1 retransmits. At that time, it is necessary to change not only the position parameter of the equation representing the surface shape of the reflection surface 40a but also the shape parameter of the equation representing the ellipse e. Furthermore, it is desirable to apply a predetermined shape correction to obtain a so-called aspherical shape. Hereinafter, with reference to FIGS. 2 to 4, the position of the reflecting surface 40 a is shifted by a predetermined distance in the direction of the optical axis X (only the position parameter is changed), or in addition to this shifting, the surface shape of the reflecting surface 40 a is aspheric. An example of improving the imaging performance will be described with reference to specific numerical examples.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, the reflecting surface 4 of the reflecting mirror 40 will be described.
The shape of 0a is expressed by the following equation (1).

[Number 1] ^{X = (h 2 / r)} / (1+ (1-K (h / r) 2) 1/2) + C 4 h 4 + C 6 h 6 + C 8 h 8 + C 10 h 10 ... formula (1 In the equation (1), K is a conical coefficient, which is a value that determines a basic shape of an ellipse forming a reflecting mirror. And
When K = 1, the basic shape is a circle, and when 0 <K <1, it is a horizontally long ellipse (having a major axis in the optical axis X direction).
When K> 1, an ellipse is vertically elongated (having a major axis in a direction perpendicular to the optical axis X). r is a reflecting mirror (aspherical surface)
Represents the radius of curvature at the bottom. The material of the valve 11 is S
It is made of iO ₂ , and its refractive index is as follows according to the wavelength λ. λ = 624 nm: n = 1.45728 λ = 829.6 nm: n = 1.45282 λ = 418.5 nm: n = 1.46824 λ = 213.0 nm: n = 1.53519

Prior to the description of the embodiment, as an ideal condition, it is assumed that the bulb 11 does not exist, so that the light emitted from the luminescent spot P is reflected by the reflecting mirror 40 and reaches the condensing point Q without bending the optical path. Table 1 and FIG. 2 show the image forming state.
3 (a) and FIG. 3 (a), and subsequently, Table 2, FIG. 2 (b) and FIG.
This will be described with reference to FIG.

As shown in the layout diagram of FIG.
And the focal point Q as a focal point, a bottom curvature radius of 160 mm,
If a reflecting mirror having a reflecting surface 40a along an elliptical surface with a conical coefficient of 0.64 is arranged, the parameters are as shown in Table 1 below.
It becomes as shown in.

[Table 1] Surface number Curvature radius Surface spacing Refractive index 0 ∞ 100.00000 (bright point) 1 -160.000 -400.000000 -1.00000 (reflective surface) 2 ∞ (image of luminescent point) (cone coefficient) K = 0.64 (aspherical surface) Coefficient) C ₄ = 0.0 C ₆ = 0.0 C ₈ = 0.0 C ₁₀ = 0.0

FIG. 3A shows a light-converging pattern calculated based on the parameters shown in Table 1. From FIG. 3A,
Light emitted from the bright spot P toward the reflecting mirror 40 is reflected by the reflecting mirror 40.
It can be seen that the light is reflected by the reflection surface 40a of FIG.

Next, as shown in FIG.
In the arrangement diagram shown in FIG.
Table 2 shows parameters in the case where a valve 11 having a diameter of 9 mm and an outer radius of 20 mm is present. 2 (b) is the same as that of FIG. 2 (a) except that a valve 11 is present. The following description will be made on the assumption that the wavelength of light is λ = 624 nm (refractive index n of the bulb 11 = 1.45728).

[Table 2] Surface number Curvature radius Surface spacing Refractive index 0 ∞ 19.000000 (bright point) 1 -19.000 1.000000 1.45728 (lamp bulb) 2 -20.000 80.000000 3 -160.000 -80.000000 -1.00000 (Reflective surface) 4 -20.000 -1.000000 -1.45728 (Lamp bulb) 5 -19.000 -19.000000 6 -19.000000 (Bright point) 7 19.000 -1.000000 -1.45728 (Lamp bulb) 8 20.000 -280.000000 9 ∞ (Image of luminescent spot) (Conical coefficient) K = 0.64 (Non C ₄ = 0.0 C ₆ = 0.0 C ₈ = 0.0 C ₁₀ = 0.0

FIG. 3B shows a light-converging pattern calculated based on the parameters shown in Table 2. From FIG. 3B,
Light emitted from the bright spot P toward the reflecting mirror 40 is reflected by the reflecting mirror 40.
It can be seen that the light is refracted when the light is reflected by the reflection surface 40a and retransmits through the bulb 11, and the imaging performance is deteriorated. This state corresponds to the state shown in FIG.

Next, Table 3, FIG. 2 (c) and FIG. 3 (c) show examples in which the imaging performance is improved when the reflecting mirror 40 is shifted by a predetermined amount δ as shown in FIG. 1 (b). It will be described with reference to FIG. In the arrangement diagram of FIG. 2C, the only difference from the arrangement diagram of FIG. 2B is that the distance between the reflection surface 40a of the reflector 40 and the bright spot P is shifted by 9.174531 mm.
There is no difference in the shape and the like of the reflection surface 40a. This FIG. 2 (c)
Table 3 shows the parameters based on the arrangement diagram. The distance of 9.174531 mm is reflected by the reflecting mirror 40 and the paraxial light of the light that re-transmits through the bulb 11 and the light reflected by the reflecting mirror 50 are condensed points Q. Is a value determined to match. The expression (1) representing the shape of the reflecting surface does not include the position parameter term that defines the position of the reflecting surface, and takes into account the shift amount of the reflecting surface position in the parameters shown in Table 3 below. .

[Table 3] Surface number Curvature radius Surface spacing Refractive index 0 ∞ 19.000000 (bright point) 1 -19.000 1.000000 1.45728 (lamp bulb) 2 -20.000 89.174531 3 -160.000 -89.174531 -1.00000 (Reflective surface) 4 -20.000 -1.000000 -1.45728 (Lamp bulb) 5 -19.000 -19.000000 6 -19.000000 (Bright point) 7 19.000 -1.000000 -1.45728 (Lamp bulb) 8 20.000 -280.000000 9 ∞ (Image of luminescent spot) (Conical coefficient) K = 0.64 (Non C ₄ = 0.0 C ₆ = 0.0 C ₈ = 0.0 C ₁₀ = 0.0

FIG. 3C shows the light-converging pattern calculated based on the parameters shown in Table 3. As shown in FIG. 3C, by correcting the position of the reflecting mirror 40 by the paraxial theory, the deterioration of the imaging performance shown in FIG. 3B is greatly improved. However, compared with the ideal imaging performance shown in FIG. 3A, there is a spread of light that cannot be completely corrected at the focal point Q. This is due to the spherical aberration as described above.

Next, Table 4, FIG. 2 (d), and FIG. 3 (d) show an example of removing the spherical aberration by setting the reflecting surface of the reflecting mirror 40 to an aspheric surface in a situation where it is required to converge more strictly. ).

In FIG. 2D, the point different from that shown in FIG. 2B is that the reflecting surface of the reflecting mirror 40 is an aspherical reflecting surface 40b, Only the point apart from the surface 40b is the same, and the other points are the same as those shown in FIG. Table 4 shows parameters based on the arrangement shown in FIG.

[Table 4] Surface number Curvature radius Surface spacing Refractive index 0 ∞ 19.000000 (bright point) 1 -19.000 1.000000 1.45728 (Lamp bulb) 2 -20.000 89.174531 3 -171.25821 -97.482182 -1.00000 (Reflective surface) 4 -20.000 -1.000000 -1.45728 (Lamp bulb) 5 -19.000 -19.000000 6 -19.000000 (Bright point) 7 19.000 -1.000000 -1.45728 (Lamp bulb) 8 20.000 -280.000000 9 ∞ (Image of luminescent point) (Cone coefficient) K = 5.4837 (Non C ₄ = 0.392621 × 10 ⁻⁷ C ₆ = −0.610856 × 10 ⁻¹⁰ C ₈ = 0.318212 × 10 ⁻¹³ C ₁₀ = −0.373059 × 10 ⁻¹⁷

FIG. 3D shows the condensing pattern calculated based on the parameters shown in Table 4. From FIG. 3D,
It can be seen that the deterioration of the imaging performance shown in FIG. 3B is further improved as compared with that of FIG. 3C, and that almost the same imaging performance as that shown in FIG. 3A can be obtained. .

Next, referring to FIG. 4, FIGS.
Will be described with reference to the graph of FIG. 4 showing the density distribution of light energy. In the graph of FIG. 4, the horizontal axis represents the image height h on the converging point Q, and the vertical axis represents the distribution of the light energy density in the image height h direction on the converging point Q. In the ideal state shown in FIG. 2A, the light energy density at the image height h = 0 on the condensing point Q is normalized as 1, and a graph is plotted as a relative energy density.

In FIG. 4, a graph shown by a curve 1 (dashed line) shows the distribution of light energy in an ideal state shown in FIG. 2 (a), and a curve 2 (fine broken line) shown in FIG. 2 (b). The distribution in a state where no correction is performed on the reflection surface 40a is shown. A curve 3 (coarse dashed line) shows the distribution in a state where the correction is applied only at the position of the reflection surface 40a as shown in FIG. 2C, and a curve 4 (solid line) as shown in FIG. 3D. The distribution in a state where the correction is performed based on the position of the reflection surface 40b and the aspherical shape is shown. As shown in FIG. 4, the imaging performance is improved by correcting the position of the reflecting mirror 40 or the position and the shape of the reflecting surface, and accordingly, the light energy density in the vicinity of the converging point Q is increased. I understand.

By the way, referring to FIG.
Considering the image magnification of the image of the luminescent spot P formed on the reflecting surface 5
The magnification of the image formed by Oa is different from the magnification of the image formed by the combined optical system of the reflecting surface 40a and the bulb 11. Therefore, the size of the image formed at the focal point Q is different, and the brightness of the image is also different. Therefore, the distribution of the light energy density at the light condensing point Q becomes non-uniform, that is, uneven brightness occurs, which is not preferable. Therefore, it is desirable to determine the shape of the reflecting surface of the reflecting mirror 40 or the amount of displacement as follows.

That is, as the first step, the reflecting mirror 40 is used.
When determining the shape of the reflection surface 40a, the magnification of the image formed by the reflection surface 50a, the reflection surface 40a and the bulb 11
The reflecting surface shape is determined so that the magnification of the image formed by the combining optical system with the above is the same. Next, as a second step, the image forming position of the image by the reflection surface 50a and the reflection surface 40a
The amount by which the reflecting mirror 40 is shifted may be determined so that the image forming position of the image formed by the combined optical system of the lens 11 and the valve 11 is matched.
At this time, the magnification also changes by shifting the position of the reflecting mirror 40, but the first and second steps described above are repeated,
What is necessary is just to perform convergence calculation. In obtaining the reflection surface shape or the amount of shift, the second step may be performed first, and then the first step may be performed.

Here, considering the three-dimensional shape of the bulb 11, for example, when the bulb 11 has a true spherical shape, the shapes of the reflection surfaces 40a, 40b, and 50a are, for example, as shown in FIG. An ellipsoidal sphere obtained by a locus when rotated about the optical axis X may be used.
Further, when the shape of the bulb 11 is not a true spherical shape, but the curvature differs between the polar direction and the perpendicular direction, the reflecting surface shape of the reflecting mirror 40 is made toric aspherical according to the curvature, Light can be efficiently condensed on the converging point Q.

In the above description of the embodiment, the portion of the reflecting mirror 50 where the reflected light does not retransmit through the bulb 11
And the reflection mirror 40 in a portion that retransmits light, and an example in which the reflection mirror 40 is shifted or has an aspherical shape to enhance the light collection performance has been described. It may be shifted. Further, the reflecting mirrors 40 and 50 may be integrally manufactured by a processing method such as molding or pressing.

In the above embodiment, the valve 11 functions as a refractive optical system.
Is not so thick, so that chromatic aberration hardly occurs as compared with a refraction-based imaging optical system or an optical system using a cone lens. In the above embodiment, the wavelength of light λ = 624.
Although described as nm, the same result as described above can be derived even if calculation is performed at another different wavelength for the above-described reason. This makes it possible to realize an illumination device having stable light-collecting performance even for a light source having a wide wavelength range or a light source having a short wavelength.

In the correspondence between the above-described embodiment and the claims, the reflecting surfaces 40a and 40b constitute the central reflecting surface, and the reflecting surfaces 50a and 50b constitute the central reflecting surface, respectively.

[0034]

(1) According to the first aspect of the present invention, the light beam is reflected by the central reflecting surface, is re-transmitted through the bulb, and is condensed and reflected by the peripheral reflecting surface. The light from the light source can be condensed to the light condensing point without wasting because the light condensing point of the light flux condensed without re-transmitting through the valve can be collected. It is possible to provide an illuminating device that has no chromatic aberration with respect to a light source having a range or a short wavelength and exhibits excellent light-collecting performance. (2) According to the second aspect of the present invention, light is condensed by matching the image magnification of a light beam condensed by re-transmitting through the valve with the image magnification of light beam condensed without re-transmitting through the valve. It is possible to suppress uneven brightness at a point and to achieve uniform illumination. (3) According to the third and fourth aspects of the present invention, the position of the central reflecting surface of the reflecting surface composed of the central reflecting surface and the peripheral reflecting surface constituting the ellipse represented by the same shape parameter. By simply displacing the light, the light flux condensed by re-transmitting through the bulb coincides with the focal point of the light flux condensed without re-transmitting through the bulb, and excellent light-collecting performance can be obtained. (4) According to the fifth and sixth aspects of the present invention, the aspherical shape of the central reflecting surface has a shape that corrects the spherical aberration that occurs when the light passes through the valve and condenses light. Excellent light-collecting performance can be obtained. In addition, the aspherical shape, the image magnification of the light flux that is transmitted again through the valve and condensed,
By determining that the image magnification of the light beam condensed without re-transmitting through the bulb is made to match, it is possible to suppress luminance unevenness at the light condensing point. (5) According to the invention as set forth in claim 7, it is possible to efficiently condense a light flux even if the bulb has a different curvature between the polar direction and the perpendicular direction.

[Brief description of the drawings]

FIGS. 1A and 1B are longitudinal sectional views schematically showing an illumination device according to an embodiment of the present invention, wherein FIG. 1A shows a state before correction of a focal point shift, and FIG. Is shown.

FIGS. 2A and 2B are layout diagrams of an optical system of a lighting device, and FIG. 2A illustrates an ideal state in which a bulb 11 does not exist around a bright point P;
(B) shows a state in which the bulb 11 exists around the luminescent spot P, and (c) shows a state in which the position of the reflection surface 40a is shifted.
(D) shows a state in which the position of the reflection surface is shifted, and the reflection surface 40b is made aspheric.

FIGS. 3A and 3B are diagrams illustrating a light condensing state of the illumination device, and FIG.
2A to 2D show light condensing states corresponding to the respective arrangements in FIGS. 2A to 2D.

FIG. 4 is a graph showing the density distribution of light energy in the image height direction on a converging point.

5A and 5B are diagrams showing a schematic configuration of a lighting device according to a conventional technique, wherein FIG. 5A shows a configuration using a refraction system, FIG. 5B shows a configuration using a reflection optical system, and FIG. An example using an off-axis optical system is shown.

[Explanation of symbols]

 Reference Signs List 10 light source 11 bulb 40, 50 reflecting mirror 40a, 40b, 50a reflecting surface

Claims (7)

[Claims] 1. A lighting device comprising: a light source having a bulb; and at least a central reflecting surface and a peripheral reflecting surface for reflecting light from the light source and condensing the light at a focal point. After being reflected, the light-collecting point of the light beam that re-transmits through the bulb and condenses, and the light-collecting point of the light beam that condenses without re-transmitting the valve after being reflected by the peripheral reflecting surface. A lighting device characterized in that the surface shape of the central reflecting surface is determined so that the values of the central reflecting surface coincide with each other. 2. The illumination device according to claim 1, wherein an imaging magnification of an image of the light source formed by the central reflecting surface and the bulb, and a light source formed by the peripheral reflecting surface alone. A lighting device characterized in that the surface shape of the central reflecting surface is determined so that the image forming magnification further matches the image forming magnification. 3. The lighting device according to claim 1, wherein the central reflecting surface and the peripheral reflecting surface form a part of an ellipse represented by the same shape parameter, and differ only in a position parameter. A lighting device, comprising: 4. The illuminating device according to claim 3, wherein the amount of difference between the position parameters is determined by a converging point position of the central reflecting surface and the bulb determined by paraxial theory, and the peripheral reflecting surface. An illuminating device characterized by being equal to a shift amount from a position of a converging point. 5. The lighting device according to claim 1, wherein the peripheral reflecting surface is an elliptical mirror, and the central reflecting surface is an aspherical mirror. 6. The illumination device according to claim 5, wherein the shape of the aspherical mirror is adjusted so that the light reflected by the central reflecting surface corrects a spherical aberration caused by re-transmitting the bulb. A lighting device characterized by the decision. 7. The lighting device according to claim 5, wherein the aspherical shape of the central reflecting surface is a toric aspherical surface.