Light source apparatus

1. A light source apparatus comprising:

a light source which emits excitation light;

an optical fiber which is optically connected to the light source, and which guides the excitation light;

a wavelength converting member which is optically connected to an emitting end portion of the optical fiber, and which receives the excitation light emitted from the emitting end portion, and makes emerge light of a wavelength area different from a wavelength area of the excitation light; and

a holding member which holds the emitting end portion of the optical fiber, a light diverging unit, and the wave length converting member,

wherein the light source apparatus has the light diverging unit which is arranged in an optical path of the excitation light, between the emitting end portion of the optical fiber and the wavelength converting member, and

the holding member comprises:

a first internal space between the emitting end portion of the optical fiber and the light diverging unit, and

a second internal space between the light diverging unit and the wavelength converting member;

wherein the light diverging unit is a plurality of light diverging optical elements formed on a plate member, the plurality of light diverging optical elements formed on the plate member is a concavo-convex surface formed on a surface of the plate member and the concavo-convex surface is disposed at random such that a distance between the convex portion and an adjacent convex portion is not more than 100 microns.

2. The light source apparatus according to claim 1 , wherein the light diverging unit has a function of widening a beam spot such that, a size of a beam spot formed on the wavelength converting member by the excitation light emitted from the optical fiber is substantially same as or smaller than a size of an effective wavelength conversion area of the wavelength converting member.

3. The light source apparatus according to claim 2 , wherein the light diverging unit includes at least an optical member having a negative refracting power which guides light.

4. The light source apparatus according to claim 1 , wherein a distance between a valley of a concave portion and a peak of a convex portion of the concavo-convex surface is not more than 100 microns.

5. The light source apparatus according to claim 1 , wherein the light diverging optical element has a concavo-convex surface formed by an imprint method, on a surface of glass or resin.

6. The light source apparatus according to claim 1 , wherein the light diverging element is a plurality of concave lenses formed on a surface of the plate member.

7. The light source apparatus according to claim 2 , wherein a size of the light diverging unit is substantially same or larger as compared to the beam spot formed on the light diverging unit by the excitation light.

8. The light source apparatus according to claim 2 , wherein a size of the wavelength converting member is substantially same or larger with respect to a beam spot formed on the wavelength converting member by the excitation light via the light diverging unit.

9. The light source apparatus according to claim 1 , wherein:

the holding member has an area between the emitting end portion of the optical fiber and the wavelength converting member, on an inner surface of the holding member is a circular conical structure having a taper angle with respect to a principal axis of the excitation light, and having a side toward the wavelength converting member wider than a side toward the emitting end portion of the optical fiber.

10. The light source apparatus according to claim 9 , wherein the circular conical structure on the inner surface of the holding member has a first taper angle θ defined as an angle between the principal axis of the excitation light and the inner surface of the holding member, between the emitting end portion of the optical fiber and the light diverting unit, and a second taper angle ψ defined as angle between the principal axis of the excitation light and the inner surface of the holding member, between the light diverging unit and the wavelength converting member, mutually different.

11. The light source apparatus according to claim 10 , wherein the second taper angle ψ is greater with respect to the first taper angle θ.

12. The light source apparatus according to claim 11 , wherein when an angle of incidence φ of the excitation light emitted from the emitting end portion of the optical fiber is calculated as φ=sin −1 NA by using a numerical aperture NA of the optical fiber, the first taper angle θ and the angle of incidence φ of the excitation light are related by a relation θ≧φ.

13. The light source apparatus according to claim 9 , wherein the inner surface of the holding member between the emitting end portion of the optical fiber and the wavelength converting member is a reflecting surface.

14. The light source apparatus according to claim 1 , wherein the light diverging unit is one concave lens, and

the light source apparatus further comprises:

an optical unit which includes at least once convex lens between the light diverging unit and the wavelength converting member, which irradiates the excitation light spread by the light diverging unit, to the wavelength converting member, upon changing the excitation light to parallel light.