Wavelength conversion laser light source, and image display device

1. A wavelength conversion laser light source, comprising:

a pump light source;

a solid laser medium to which pump light from the pump light source is input and which generates a fundamental light wave;

a wavelength conversion element which converts the fundamental light wave into a second harmonic light wave having a higher frequency than the frequency of the fundamental light wave;

a concave mirror on which a first reflecting surface reflecting the fundamental light wave and the second harmonic light wave is formed; and

a wavelength plate on which an optical film is formed,

wherein the optical film includes a second reflecting surface reflecting the fundamental light wave and transmitting the second harmonic light wave;

a laser resonator is constituted by the first reflecting surface and the second reflecting surface;

the solid laser medium is arranged on the first reflecting surface side of the laser resonator, the wavelength plate is arranged on the second reflecting surface side of the laser resonator, and the wavelength conversion element is arranged between the solid laser medium and the wavelength plate;

the solid laser medium outputs light other than linearly polarized light as the fundamental light wave;

the light other than linearly polarized light is directly input from the solid laser medium to the wavelength conversion element; and

the wavelength plate outputs the second harmonic wave converted by the wavelength conversion element to an exterior of the laser resonator via the second reflecting surface.

2. The wavelength conversion laser light source according to claim 1 , wherein

the first reflecting surface formed on the concave mirror reflects the fundamental light wave and condenses the fundamental light wave on the wavelength conversion element, and

the second reflecting surface formed on the wavelength plate is a plane mirror.

3. The wavelength conversion laser light source according to claim 1 , wherein the second reflecting surface formed on the wavelength plate is exposed to external air.

4. The wavelength conversion laser light source according to claim 1 , further comprising a cooling section which cools the wavelength plate.

5. The wavelength conversion laser light source according to claim 4 , wherein the cooling section is made from a metal film having a resistivity of not more than 1.0×10 −5 Ω·cm.

6. The wavelength conversion laser light source according to claim 4 , wherein the cooling section is made from diamond thin film or diamond-like carbon.

7. The wavelength conversion laser light source according to claim 1 , wherein the solid laser medium is made from an isotropic material having a refractive index that is isotropic.

8. The wavelength conversion laser light source according to claim 1 , wherein the solid laser medium is made from a ceramic material having a depolarization effect.

9. The wavelength conversion laser light source according to claim 1 , wherein the wavelength conversion element is made from any one of MgO-doped lithium niobate, MgO-doped lithium tantalite and potassium titanyl phosphate.

10. An image display device, comprising:

a laser light source which includes the wavelength conversion laser light source according to claim 1 and generates laser light;

a modulation element which forms an image by modulating the laser light; and

a controller which controls the laser light source and the modulation element.