Light source device and image display apparatus
View Patent ↗A light source device includes a phosphor layer formed on a base, and an excitation light source exciting the phosphor. A dichroic mirror is arranged between the phosphor layer and the excitation light source and inclined with respect to a propagation direction of excitation light from the excitation light source. An incident region of the excitation light and an exiting region of fluorescence emitted from the phosphor belong to a space on the same side with respect to the surface with the phosphor layer disposed. In a dominant wavelength of the excitation light, the dichroic mirror has a spectral characteristic of transmitting 50% or more of light of a p-polarized component and reflecting 50% or more of light of a s-polarized component. Fluorescence emitted from the phosphor layer can be extracted highly efficiently and propagated by a compact and simple optical system.
1. A light source device comprising: a phosphor layer formed by disposing a phosphor on a surface of a base; and an excitation light source exciting the phosphor,
wherein a dichroic mirror is arranged between the phosphor layer and the excitation light source so as to be inclined with respect to a propagation direction of excitation light from the excitation light source,
an incident region of the excitation light exiting from the excitation light source and an exiting region of fluorescence emitted from the phosphor belong to a space on the same side with respect to the surface on which the phosphor layer is disposed, and
in a dominant wavelength of the excitation light, the dichroic mirror has a spectral characteristic of transmitting 50% or more of light of a p-polarized component and reflecting 50% or more of light of a s-polarized component.
2. The light source device according to claim 1 ,
wherein the phosphor layer is arranged in a direction in which the excitation light entering the dichroic mirror from the excitation light source is transmitted through the dichroic mirror, and
in a dominant wavelength range of the fluorescence emitted from the phosphor, the dichroic mirror has a spectral characteristic of having a high reflectance.
3. The light source device according to claim 2 , wherein at a position in a direction in which the excitation light entering the dichroic mirror from the excitation light source is reflected by the dichroic mirror, a polarization converter with respect to the excitation light having been reflected by the dichroic mirror and a mirror surface reflecting the excitation light having passed through the polarization converter are provided.
4. The light source device according to claim 3 , wherein the polarization converter is a quarter wave plate with respect to the excitation light.
5. The light source device according to claim 1 ,
wherein the phosphor layer is arranged in a direction in which the excitation light entering the dichroic mirror from the excitation light source is reflected by the dichroic mirror, and
in a dominant wavelength range of the fluorescence emitted from the phosphor, the dichroic mirror has a spectral characteristic of having a high transmittance.
6. The light source device according to claim 4 , wherein at a position in a direction in which the excitation light entering the dichroic mirror from the excitation light source is transmitted through the dichroic mirror, a polarization converter with respect to the excitation light having been transmitted through the dichroic mirror and a mirror surface reflecting the excitation light having passed through the polarization converter are provided.
7. The light source device according to claim 6 , wherein the polarization converter is a quarter wave plate with respect to the excitation light.
8. The light source device according to claim 1 , wherein a polarization converter with respect to the excitation light is arranged between the phosphor layer and the dichroic mirror.
9. The light source device according to claim 8 , wherein the polarization converter is a quarter wave plate with respect to the excitation light.
10. The light source device according to claim 1 , wherein a condensing optical system is arranged between the phosphor layer and the dichroic mirror.
11. The light source device according to claim 1 , wherein the excitation light source is a laser light source oscillating in a wavelength range of blue.
12. The light source device according to claim 1 , wherein the phosphor emits fluorescence containing light of a wavelength range of red, yellow or green as a main component when excited by the excitation light source.
13. The light source device according to claim 1 , wherein the surface of the base on which the phosphor layer is disposed is a mirror surface reflecting fluorescence.
14. The light source device according to claim 1 , wherein the base can be controlled to rotate.
15. The light source device according to claim 14 , wherein the surface of the base on which the phosphor layer is disposed is divided into two or more segments spacially.
16. The light source device according to claim 15 , wherein at least in one of the segments, the surface of the base is not provided with the phosphor layer, and is a mirror surface reflecting excitation light.
17. An image display apparatus, comprising
a light source device;
a spatial light modulation element;
an illumination optical system allowing light from the light source device to enter the spatial light modulation element; and
a projection optical system projecting an image ejected from the spatial light modulation element onto a screen,
wherein the light source device is the light source device according to claim 1 .