Light source device and projection display apparatus

1. A light source device comprising:

a light source configured to emit laser light;

an optical system having an optical axis for guiding the laser light;

a first prism which is disposed between the light source and the optical system and includes a first incident surface on which the laser light is incident, and a first exit surface inclined with respect to the first incident surface;

a second prism which is disposed between the first prism and the optical system and includes a second incident surface facing the first exit surface at an interval, and a second exit surface inclined with respect to the second incident surface; and

a driver configured to rotate the first and second prisms around the optical axis continuously in a state in which the first exit surface and the second incident surface are inclined with respect to the optical axis so that an optical path length between the first exit surface and the second incident surface is changed periodically,

wherein the optical system includes a condensing optical system disposed to condense laser light incident from the second prism,

wherein the optical system further includes an integrator optical system disposed to diffuse the laser light condensed by the condensing optical system.

2. The light source device according to claim 1 , wherein the first and second prisms are disposed so that the first incident surface and the second exit surface are orthogonal to the optical axis.

3. The light source device according to claim 1 , wherein the driver rotates the first and second prisms with the optical axis being a rotation center.

4. The light source device according to claim 1 ,

wherein the light source includes a plurality of semiconductor lasers, and

wherein the light source device further includes an incident optical system which collimates laser light emitted from the light source to enter the first incident surface of the first prism.

5. The light source device according to claim 4 , wherein the plurality of semiconductor lasers include semiconductor lasers for a plurality of colors.

6. The light source device according to claim 1 , wherein an optical material is filled in an interval between the first exit surface and the second incident surface, the optical material having a refractive index different from a refractive index of the first and second prisms.

7. A projection display apparatus comprising:

a light source device; and

an image generator configured to generate image light based on light from the light source device, wherein the light source device comprises:

a light source configured to emit laser light;

an optical system having an optical axis for guiding the laser light;

a first prism which is disposed between the light source and the optical system and includes a first incident surface on which the laser light is incident, and a first exit surface inclined with respect to the first incident surface;

a second prism which is disposed between the first prism and the optical system and includes a second incident surface facing the first exit surface at an interval, and a second exit surface inclined with respect to the second incident surface; and

a driver configured to rotate the first and second prisms around the optical axis continuously in a state in which the first exit surface and the second incident surface are inclined with respect to the optical axis so that an optical path length between the first exit surface and the second incident surface is changed periodically.

8. The light source device according to claim 1 , comprising a color separation wheel which separates an incident light transmitting the first prism and the second prism into color beams in a time division.

9. The projection display apparatus according to claim 7 , wherein the first and second prisms are disposed so that the first incident surface and the second exit surface are orthogonal to the optical axis.

10. The projection display apparatus according to claim 7 , wherein the optical system includes a condensing optical system disposed to condense laser light incident from the second prism.

11. The projection display apparatus according to claim 10 , wherein the optical system further includes an integrator optical system disposed to diffuse the laser light condensed by the condensing optical system.

12. The projection display apparatus according to claim 7 , wherein the driver rotates the first and second prisms with the optical axis being a rotation center.

13. The projection display apparatus according to claim 7 , wherein the light source includes a plurality of semiconductor lasers, and wherein the light source device further includes an incident optical system which collimates laser light emitted from the light source to enter the first incident surface of the first prism.

14. The projection display apparatus according to claim 13 , wherein the plurality of semiconductor lasers include semiconductor lasers for a plurality of colors.

15. The projection display apparatus according to claim 7 , wherein an optical material is filled in an interval between the first exit surface and the second incident surface, the optical material having a refractive index different from a refractive index of the first and second prisms.

16. The projection display apparatus according to claim 7 , comprising a color separation wheel which separates an incident light transmitting the first prism and the second prism into color beams in a time division.