JP2000089158A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device that improvement in utilization of light, uniformalizing of intensity distribution of emitted light, and reduction in a diameter of the emitted light beam can be achieved at the same time. SOLUTION: In this light source device, the whole light emitted from a reflector 3 is separated into plural light fluxes by a condenser lens array 11. These separated light fluxes are converted into a luminous flux L1 having an annular cross section and a uniform light intensity by the conversion lens 12. This luminous flux L1 is narrowed by being reflected by each reflecting interface 21a and 22a of a 1st reflection mirror 21 and a 2nd reflection mirror 22 and converted into a circular cross sectional luminous flux L2. Therefore, the diameter of the luminous flux L2 becomes smaller than the outer diameter of the annular cross sectional luminous flux L1. According to such a light source device, it is possible to achieve improvement in light utilization efficiency, uniformalizing of intensity distribution of emitted light, and reduction in a diameter of the emitted light beam at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device having high light use efficiency used for a slide projector, a liquid crystal projector, and the like.

[0002]

2. Description of the Related Art A light source device 100 as shown in FIG. 5A is used in a liquid crystal projector. FIG. 5 (A)
The light source device 100 shown in FIG. 1 includes a lamp 2 such as a metal halide lamp, and a parabolic reflector 3 having a circular emission opening 4. A lamp mounting hole 3b is formed in the center of the bottom of the parabolic reflector 3, and one end of the lamp 2 is fixed to this end via a base.

In this light source device 100, light emitted from a lamp light emitting portion 2a of a lamp 2 is reflected by a parabolic reflecting mirror 3 and converted as light substantially parallel to the lamp optical axis L from a front circular emission opening 4. Be injected. The diameter of the emitted light beam is determined by the focal length of the parabolic reflector 3 and the angle (light distribution angle) of the light emitted from the lamp 2.

Further, a light source device 100A as shown in FIG. 5B is used for the slide projector. FIG. 5 (B)
A light source device 100A shown in FIG.
, A spherical reflecting mirror 5 arranged on one side of the lamp light emitting portion 2a and a condenser lens 6 arranged on the other side.

In the light source device 100A, the light emitted from the lamp light emitting portion 2a of the lamp 2 is divided into a light component going to the spherical reflecting mirror 5 and a light component going directly to the condenser lens 6. The light component directed to the spherical reflecting mirror 5 is reflected by the spherical reflecting mirror 5 and re-enters the lamp light emitting unit 2a, and thereafter, travels from the light emitting unit 2a to the condenser lens 6.

Accordingly, the light emitted from the lamp light emitting section 2a finally reaches the condenser lens 6 and is emitted by this lens 6 as a light beam having a predetermined angle.

[0007]

In recent years, there has been a strong demand for a light source device used in a liquid crystal projector or the like to efficiently use light emitted from a lamp and to make the light intensity distribution of emitted light uniform. Therefore, there is an urgent need to develop a light source device that satisfies these requirements.
However, the light source devices 100 and 100A shown in FIGS. 5A and 5B have the following problems to be solved.

First, in the light source device 100 shown in FIG. 5A, the light intensity near the lamp optical axis decreases. The reason is that in the light source device 100, the vicinity of the lamp optical axis of the emitted light is a shadow of the lamp 2. Although the lamp 2 may be made smaller to narrow the range in which the light intensity decreases, the decrease in light intensity near the lamp optical axis cannot be completely eliminated. Therefore, in the light source device 100 having this configuration, it is not possible to obtain emitted light having a uniform light intensity distribution.

On the other hand, the light source device 100A shown in FIG.
In this case, light is emitted in a direction perpendicular to the lamp optical axis L, so that there is no portion that becomes a shadow of the lamp 2 and emitted light having a uniform light intensity distribution can be obtained. However, only a part of the light emitted from the lamp light emitting portion 2a of the lamp 2 can be used. One of the factors is that the light component returned by the spherical reflecting mirror 3c receives light loss due to reflection on the light emitting unit surface. Therefore, in the light source device 100A having this configuration, the light use efficiency is low.

Here, in a device in which the light source device is incorporated, for example, a liquid crystal projector or the like, it is possible to reduce the size of the device by reducing the diameter of the light beam emitted from the light source device.

[0011] In view of the above, an object of the present invention is to provide:
An object of the present invention is to provide a light source device capable of simultaneously improving the light use efficiency and making the light intensity distribution of the emitted light uniform. Another object of the present invention is to provide a light source device that can also reduce the diameter of emitted light.

[0012]

In order to solve the above-mentioned problems, the present invention provides a lamp and a reflector which reflects light emitted from the lamp and emits the light in a direction parallel to the lamp optical axis of the lamp. The light source device having the following configuration is employed.

That is, a first optical element for converting light reflected by the reflector into a light beam having an annular cross section having a uniform light intensity distribution, and converting the light beam having the annular cross section into a light beam having the annular cross section. And a second optical element that converts the light beam into a light beam having a circular cross section smaller than the outer diameter of the second optical element.

The second optical element may include a first reflecting mirror having a frustoconical inner peripheral reflecting surface narrowed toward the light emitting side, and a conical shape narrowed toward the light emitting side. And a second reflection mirror having an outer peripheral reflecting surface in a shape.
Then, the first and second reflection mirrors are arranged coaxially about the lamp optical axis at a position on the light emission side with respect to the first optical element. further,
The second reflection mirror is disposed at a position inside the first reflection mirror. Then, the light flux having the annular cross section is configured to be guided to the inner peripheral reflection surface of the first reflection mirror.

In the light source device of the present invention, the light reflected by the reflector is converted by the first optical element into a light beam having an annular cross section with a uniform light intensity distribution. That is, light having a reduced light intensity near the lamp optical axis is converted into a light beam having an annular cross section with a uniform light intensity distribution. Thereafter, the light beam is converted into a light beam having a circular cross section having a diameter smaller than the outer diameter of the light beam having an annular cross section by the first reflection mirror and the second reflection mirror. Therefore, a light beam having a circular cross section with a uniform light intensity distribution can be emitted as emission light. Further, since the light beam is converted into a light beam having a circular cross section having a diameter smaller than the outer diameter of the light beam having an annular cross section, the diameter of light emitted from the light source device can be reduced. If the diameter of the emitted light can be reduced in this manner, the size and size of an optical device such as a liquid crystal projector in which the light source device is incorporated can be reduced.

The light source device of the present invention employs a configuration in which light emitted from the lamp is reflected by the reflector. Therefore, the light source device has a configuration in which a spherical reflecting mirror and a condenser lens are disposed on the left and right of the lamp. Light use efficiency can be improved as compared with the above.

As the first optical element, a configuration including a condenser lens array disposed on the light exit side of the reflector and a conversion lens disposed on the light exit side of the condenser lens array is employed. it can. In this case, the condenser lens array is provided with a plurality of microlenses for dividing the light reflected by the reflector into a plurality of lights and condensing each light at a predetermined position. Then, the light beam having the annular cross section may be generated from the light split by the plurality of microlenses by the conversion lens.

As the condenser lens array, it is possible to use an annular lens lacking a central portion centered on the lamp optical axis. That is, since the light intensity distribution in the vicinity of the lamp optical axis is reduced by the lamp attached to the reflector, even if the above condensing lens array is used, most of the light emitted from the reflector is generated as the emitted light. It can be used as light to perform.

When a condensing lens array having a plurality of microlenses is used, a lens having a plurality of microlenses paired with the microlenses is used as the conversion lens, and the light is emitted from each of the microlenses. The luminous flux having the annular cross section may be generated by connecting the luminous fluxes having the circular cross section concentrically.

Here, the light source device of the present invention is also applicable to a light source device provided with a polarization conversion optical system for aligning the polarization direction of light reflected by the reflector. As the polarization conversion optical system, a configuration having a half-wave plate and a polarization separation film can be adopted. In the case of such a polarization conversion optical system, for example, the polarization separation film is disposed on the light emission side of the conversion lens at a position inside the first reflection mirror, and the half-wave plate is The configuration may be such that it is disposed on the reflection side of the first reflection mirror at a position inside the one reflection mirror.

According to such a configuration, one of the light beams having an annular cross section from the conversion lens passes through the polarization separation film and reaches the outer peripheral reflection surface of the first reflection mirror, while the other polarization light beam passes through the polarization separation film. The polarized light is reflected by the polarization splitting film and reaches the inner peripheral reflection surface of the second reflection mirror. The polarized light that has reached the outer peripheral reflection surface is reflected there, passes through a half-wave plate, and has a polarization surface of 90 °.
Rotated by degrees. As a result, the same polarization plane as that of one polarized light is obtained. Thereafter, the polarized light reaches the inner peripheral reflecting surface of the second reflecting mirror, is reflected by this surface, and is combined with one polarized light. As a result, light with a uniform polarization plane is emitted from the light source device.

Further, the polarization conversion optical system may be configured to include a quarter wavelength plate and a polarization separation film. In the case of such a polarization conversion optical system, the polarization splitting film is provided with the first
At the inner position of the reflection mirror, and the １ ／ wavelength plate may be disposed on the inner peripheral reflection surface of the first reflection mirror.

According to this configuration, of the light flux having an annular cross section from the conversion lens, the polarized light transmitted through the polarization separating film is
1/4 wave plate before reflection on outer peripheral reflection surface
After passing through once and being reflected by the outer peripheral reflection surface, the light passes through the quarter-wave plate once again. Since the light passes through the quarter-wave plate twice in this manner, the polarization plane of this light becomes the same polarization plane as the polarized light reflected by the polarization separation film. Therefore, even with such a polarization conversion optical system, the polarization directions of the light emitted from the reflector can be made uniform.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a light source device according to the present invention will be described with reference to the drawings. FIG. 1A is a schematic configuration diagram of a light source device. As shown in FIG.
Has a lamp 2 and a reflector 3 that reflects light emitted from the lamp 2 and emits the light in a direction parallel to the lamp optical axis L of the lamp 2. Further, the light source device 1
A first optical element 1 that converts light reflected by the reflector 3 into a light flux L1 having a uniform light intensity distribution and having an annular cross section.
0, and a second optical element 20 for converting the light beam L1 having an annular cross section from the first optical element 10 into a light beam L2 having a circular cross section having a diameter smaller than the outer diameter of the light beam L1. .

The lamp 2 is, for example, a metal halide lamp, a high-pressure mercury lamp, a xenon lamp, or the like. The reflector 3 is, for example, a parabolic reflector or a spherical reflector.
The light radiated from the lamp light emitting portion 2a of the lamp 2 is directly reflected by the reflecting surface 3a of the reflector 3, becomes substantially parallel light as a whole, and is emitted from the circular emission opening 4 of the reflector 3.

In the light source device 1, the first optical element 10 is arranged on the light exit side of the circular exit opening 4 of the reflector 3. The first optical element 10 includes a condenser lens array 11 disposed on the light exit side of the circular exit aperture 4 and a conversion lens 12 disposed on the light exit side of the condenser lens array 11. Condensing lens array 11 and conversion lens 12
Are arranged in a posture orthogonal to the lamp optical axis L, and are arranged coaxially about the lamp optical axis L.

As shown in FIG. 1B, the condenser lens array 11 includes a total of four microlenses 11a which are divided into two in each of the vertical and horizontal directions. These microlenses 11a are lenses having a refractive power of a convex lens, and have a function of condensing incident light at a predetermined position.
The light emitted from the circular emission opening 4 of the reflector 3 is divided into four by the microlenses 11a, and emitted toward predetermined light condensing positions.

The conversion lens 12 is a ring-shaped lens, and is disposed at a position closer to the condenser lens array 11 than the condenser position of the micro lens 11a. Therefore,
The light emitted from each microlens 11a enters the conversion lens 12. In the conversion lens 12 of the present example, the lens surface 121 on the incident side is a curved surface curved inward with a predetermined curvature, and has a refractive power of a concave lens. That is, the conversion lens 12 is set at the focal point of the micro lens 11a.
Has a negative focus. As a result, the conversion lens 12 generates a light flux L1 having an annular cross section having a uniform light intensity distribution from the light emitted from each microlens 11a of the condenser lens array 11. In the light source device 1 of the present example, the conversion lens 12 is set so that the width A of the light flux L1 having the annular cross section is の of the diameter B of the light-free portion at the center.
(The diameter of the central hollow portion) and its optical characteristics are set.

The second optical element 20 is arranged on the light exit side of the conversion lens 12. The second optical element 20 includes a first reflection mirror 21 having a truncated conical inner peripheral reflection surface 21a converging toward the light exit side, and a conical outer periphery converging toward the light exit side. A second reflection mirror 22 having a reflection surface 22a is provided.

The first reflecting mirror 21 is connected to the conversion lens 12
Are arranged coaxially around the lamp optical axis L. Further, a cross section obtained when the inner peripheral reflecting surface 21a of the first reflecting mirror 21 is cut along the lamp optical axis L is inclined by 45 degrees with respect to the lamp optical axis L. The second reflection mirror 22 is a first reflection mirror 2
Similarly to 1, on the light emission side of the conversion lens 12, the conversion lens 12 is coaxially arranged about the lamp optical axis L. Also,
The second reflection mirror 22 is arranged at a position inside the first reflection mirror 21. The cross section obtained when the outer peripheral reflecting surface 22a of the reflecting mirror 22 is cut along the lamp optical axis L is inclined by 45 degrees with respect to the lamp optical axis L.

All of the light beams L1 having an annular cross section emitted from the conversion lens 12 have an inner peripheral reflecting surface 21 of the first reflecting mirror 21 and an outer peripheral reflecting surface 2 of the second reflecting mirror 22.
The light is taken into the annular space defined by 2 and reaches the inner peripheral reflection surface 21a. The light that has reached the inner peripheral reflection surface 21a is bent inside at this surface 21a, that is, at a right angle toward the lamp optical axis L.

The light bent toward the lamp optical axis L enters the outer peripheral reflection surface 22 a of the second reflection mirror 22.
The light incident on the outer peripheral reflecting surface 22a is reflected at a right angle to become a light beam L2 having a circular cross section parallel to the lamp optical axis L. That is, the light beam L1 having an annular cross section emitted from the conversion lens 12 is narrowed down at its central portion and converted into a light beam L2 having a circular cross section having a diameter smaller than the outer diameter of the light beam L1. Thereafter, the light is emitted from the circular emission opening 21b of the first reflection mirror 21 to the outside.

Here, the light intensity of the light emitted from the circular emission opening 4 of the reflector 3 in the vicinity of the lamp optical axis decreases, but in the light source device 1 of the present embodiment, this light is transmitted to the first optical element 10. , The light is once converted into a light flux L1 having an annular cross section with a uniform light intensity distribution. Thereafter, the light beam L1 having the annular cross section is narrowed down by the second optical element 20, and shaped into a light beam L2 having a circular cross section having a diameter smaller than the outer diameter of the light beam L1 having the annular cross section. Therefore, it is possible to obtain a light beam having a circular cross section with a uniform light intensity distribution. Further, the diameter of the light emitted from the light source device 1 can be reduced. If the diameter of the emitted light can be reduced,
Accordingly, it is possible to reduce the size and size of a device incorporating the light source device 1, for example, a liquid crystal projector.

Further, in the light source device 1, all of the light emitted from the circular emission opening 4 of the reflector 3 passes through the first and second optical elements 10 and 20, thereby forming a light beam L2 having a circular cross section. Is converted. Therefore, the light use efficiency can be improved as compared with the light source device 100A in which the spherical reflecting mirror 5 and the condenser lens 6 are arranged on the left and right of the lamp light emitting portion 2a of the lamp 2.

In the light source device 1, the light emitted from each microlens 11a is collimated by the conversion lens 12 by making the negative focus of the conversion lens 12 coincide with the focus of each microlens 11a. Instead, as shown in FIG. 2, it is also possible to use a conversion lens 12A having a convex lens surface 121 on the incident side.
That is, by setting the focal point of the conversion lens 12A to the focal point of each micro lens 11a, the light emitted from each micro lens 11a can be parallelized by the conversion lens 12A.

The condensing lens array 11 has 4
The present invention is not limited to one provided with one microlens 11a, and may be provided with two, three, or five or more microlenses.

Further, since the light intensity distribution of the light emitted from the circular emission opening 4 of the reflector 3 in the vicinity of the lamp optical axis is low, an annular light condensed without the central portion 11b as shown in FIG. It is also possible to use the lens array 11A. That is, even if such a condenser lens array 11A is used, almost all of the light emitted from the lamp 2 can be used as light for generating emission light.

Further, when the condenser lens arrays 11 and 11A having a plurality of microlenses 11a are used, a conversion lens having a plurality of microlenses paired with the microlenses 11a is used to convert each microlens. The light flux L1 having an annular cross section may be generated by connecting the emitted light fluxes having a circular cross section concentrically.

For example, when a condenser lens array in which eight microlenses 11a are arranged concentrically is used, a conversion lens in which eight microlenses are arranged concentrically is used. When the conversion lens is disposed closer to the condenser lens array than the condenser position of the micro lens 11a,
Each microlens has a concave lens refractive power. On the other hand, the conversion lens is located at a second position
In the case of being disposed on the side of the optical element 20, each microlens has a refractive power of a convex lens. In this manner, as shown in FIG. 3, the light flux L having a circular cross section
3 are emitted and these light beams L3 are concentrically connected to form a light beam L1 having a circular cross section as a whole.

Further, the cross sections of the inner peripheral reflecting surface 21a and the outer peripheral reflecting surface 22a of each of the reflecting mirrors 21 and 22 need not necessarily be inclined at 45 degrees with respect to the lamp optical axis L.
It may be a convex curved surface or a concave curved surface having a predetermined curvature. By adjusting the curved shapes of these reflection curved surfaces, it is possible to adjust the parallelism of a light beam having a circular cross section emitted from the light source device 1.

In a liquid crystal projector using a liquid crystal panel as a light valve, the light valve handles only a specific polarized light. For this reason, it is desirable that the light source device used for the liquid crystal projector can emit a specific polarized light.

FIGS. 4A and 4B show a part of such a light source device. First, the example shown in FIG. 4A is obtained by adding a polarization conversion optical system 30 to the light source device 1. The polarization conversion optical system 30 includes a 波長 wavelength plate 31 and a polarization separation element 32. The polarization separation element 32 includes a polarization separation film 32a inclined at 45 degrees with respect to the lamp optical axis L. The optical characteristics of the polarized light separating film 32a are set so as to transmit P-polarized light and reflect S-polarized light. The half-wave plate 31 is arranged on the reflection side of the first reflection mirror 21.

In the light source device 1 provided with the polarization conversion optical system 30, the light beam L1 having an annular cross section emitted from the conversion lens 12 enters the polarization separation element 32. The light beam L1 having an annular cross section is light in which S-polarized light and P-polarized light are mixed. Therefore, the light beam L incident on the polarization separation element 32
1, the S-polarized light is transmitted through the polarization separation film 32a to the lamp optical axis L.
Is reflected at right angles to the polarization separation film 3
2a.

The S-polarized light reflected by the polarization separation film 32a is reflected by the outer peripheral reflection surface 22a of the second reflection mirror 22, and is converted into a light beam parallel to the lamp optical axis L. On the other hand, the P-polarized light transmitted through the polarization separation film 32a reaches the inner peripheral reflection surface 21a of the first reflection mirror 21, and is reflected at a right angle toward the lamp optical axis L by this surface 21a. Reflected P
The polarized light is １ ／ which is disposed on the reflection side of the inner peripheral reflection surface 21a.
The light passes through the wave plate 31. As a result, the P-polarized light is converted into S-polarized light by rotating the polarization plane by 90 degrees.

The converted S-polarized light is supplied to the second reflection mirror 2
The light is reflected by the outer peripheral reflection surface 22a of the second light source 2, is converted into a light beam in a state parallel to the lamp optical axis L, and is combined with the S-polarized light reflected by the polarization separation film 32a. As a result, a light beam L2 having a circular cross section with a uniform polarization direction is emitted from the circular emission opening 21b of the first reflection mirror 21.

The half-wave plate 31 may be disposed at a position where only the P-polarized light separated by the polarization separation element 32 passes. For example, it can be arranged on the exit plane of the P-polarized light in the polarization splitting element 32.

The polarization conversion optical system 30A shown in FIG.
Comprises a polarization separation element 32 and a quarter-wave plate 33 attached to the inner peripheral reflection surface 21 a of the first reflection mirror 21. In the polarization conversion optical system 30A, similarly to the polarization conversion optical system 30, of the light flux L1 having an annular cross section emitted from the conversion lens 12, S-polarized light is orthogonally directed toward the lamp optical axis L by the polarization separation film 32a. And the P-polarized light is transmitted through the polarized light separating film 32a. The S-polarized light reflected by the polarization separation film 32a is reflected on the outer peripheral reflection surface 2 of the second reflection mirror 22.
The light is reflected by 2a, and is converted into a light beam parallel to the lamp optical axis L.

On the other hand, the P-polarized light transmitted through the polarization separating film 32a is directed toward the inner peripheral reflecting surface 21a of the first reflecting mirror 21, and 1 / prior to entering the inner peripheral reflecting surface 21a.
The light passes through the four-wavelength plate 33. Thereafter, the light is reflected by the inner peripheral reflection surface 21a and again passes through the １ ／ wavelength plate. As a result, P
The polarized light passes through the quarter-wave plate 33 twice, which is equivalent to passing through the half-wave plate once. Therefore, the polarization plane of the P-polarized light is rotated by 90 degrees and converted to S-polarized light.
The converted S-polarized light is reflected by the outer peripheral reflection surface 22a of the second reflection mirror 22, converted into a light flux parallel to the lamp optical axis L, and combined with the S-polarized light reflected by the polarization separation film 32a. You. Therefore, even by incorporating the polarization conversion optical system 30A, the light beam L2 having a circular cross section with a uniform polarization direction can be emitted from the circular emission opening 21b of the first reflection mirror 21.

It should be noted that the polarization conversion optical system is not limited to these two examples, and the position where the polarization conversion optical system is disposed is also on the light exit side or light entrance side of the second optical element 20. Is also good. In addition, the position is not limited to between the first and second optical elements 10 and 20, but may be between the circular exit opening 4 of the reflector 3 and the first optical element 20.

[0050]

As described above, in the light source device of the present invention, the light emitted from the reflector generates a light beam having an annular cross section with a uniform light intensity distribution. Thereafter, the light beam having a circular cross section is converted into a light beam having a circular cross section having a diameter smaller than the outer diameter of the light beam. Therefore, it is possible to provide a light source device capable of emitting a light beam having a circular cross section with a uniform light intensity distribution. Further, the diameter of the light beam emitted from the light source device can be reduced. If the diameter of the light beam emitted from the light source device can be reduced, the size and size of the light source device such as a liquid crystal projector in which the light source device is incorporated can be reduced accordingly.

Further, the light source device of the present invention employs a configuration in which light emitted from the lamp is reflected by the reflector and emitted in a direction parallel to the lamp optical axis. Light use efficiency can be improved as compared with a light source device having a configuration in which a condenser lens is arranged.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram of a light source device to which the present invention is applied, FIG. 1B is a perspective view showing an external shape of a condenser lens array in the light source device, and FIG. FIG.

FIG. 2 is a diagram showing another example of a conversion lens in the light source device.

FIG. 3 is a diagram showing another example of a light beam having an annular cross section emitted from a conversion lens.

FIG. 4A is a diagram showing an example of a polarization conversion optical system, and FIG.
FIG. 4 is a diagram showing another example of the polarization conversion optical system.

FIG. 5 is a schematic configuration diagram of a conventional light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source device 2 Lamp 3 Lamp light-emitting part 10 1st optical element 11, 11A Condensing lens array 11a Micro lens 12, 12A Conversion lens 20 2nd optical element 21 First reflection mirror 21a Of 1st reflection mirror Circumferential reflection surface 22 Second reflection mirror 22a Outer peripheral reflection surface of second reflection mirror 30, 30A Polarization conversion optical system 31 1/2 wavelength plate 32 Polarization separation element 32a Polarization separation film 33 1/4 wavelength plate L Lamp optical axis L1 Light flux with circular cross section L2 Light flux with circular cross section

Claims (7)

[Claims] 1. A light source device comprising: a lamp; and a reflector that reflects light emitted from the lamp and emits the light in a direction parallel to a lamp optical axis of the lamp, wherein the light reflected by the reflector is uniform. A first optical element that converts the light into a light beam having an annular cross section having a light intensity distribution;
A second optical element that converts the light beam having the circular cross section into a light beam having a circular cross section having a diameter smaller than the outer diameter of the light beam having the circular cross section, wherein the second optical element is disposed on the light emitting side. A first reflecting mirror having a frusto-conical inner reflecting surface narrowed toward the light source; and a second reflecting mirror having a conical outer reflecting surface narrowed toward the light exit side. Wherein the first and second reflection mirrors are arranged coaxially about the lamp optical axis on the light emission side of the first optical element, and wherein the second reflection mirror is A light source device, wherein the light source device is disposed at an inner position of the first reflection mirror, and is configured to guide the light flux having the annular cross section to the inner peripheral reflection surface of the first reflection mirror. 2. The condensing lens array according to claim 1, wherein the first optical element includes a condenser lens array disposed on a light exit side of the reflector, and a conversion lens disposed on a light exit side of the condenser lens array. The condensing lens array includes a plurality of microlenses that divides the light reflected by the reflector into a plurality of lights and condenses each of the lights at a predetermined position. A light source device that generates a light flux having the annular cross section from light split by a plurality of microlenses. 3. The light source device according to claim 2, wherein the condenser lens array is an annular lens lacking a central portion centered on the lamp optical axis. 4. The conversion lens according to claim 2, wherein the conversion lens includes a plurality of microlenses paired with the microlenses, and the light beam having the annular cross section is circularly emitted from each of the microlenses. A light source device, wherein light beams having cross sections are connected concentrically. 5. The light source device according to claim 1, further comprising: a polarization conversion optical system for aligning the polarization direction of light reflected by the reflector. 6. The polarization conversion optical system according to claim 5, wherein the polarization conversion optical system includes a half-wave plate and a polarization splitting film, wherein the polarization splitting film is located inside the first reflection mirror. The レ ン ズ wavelength plate is disposed on the light exit side of the conversion lens, and the 波長 wavelength plate is disposed on the reflection side of the first reflection mirror at a position inside the first reflection mirror. Light source device. 7. The polarization conversion optical system according to claim 5, wherein the polarization conversion optical system includes a quarter-wave plate and a polarization separation film, wherein the polarization separation film is located inside the first reflection mirror. The light source device is arranged on the light emission side of the conversion lens, and the 波長 wavelength plate is arranged on the inner peripheral reflection surface of the first reflection mirror.