Laser source device, wavelength conversion element, method of manufacturing wavelength conversion element, projector, and monitoring device

1. A laser source device comprising:

a light emission unit which emits laser beam having first wavelength;

a first mirror which selectively reflects S-polarized light contained in the first wavelength laser beam emitted from the light emission unit in a direction different from the direction toward the light emission unit and transmits second wavelength laser beam;

a second mirror which receives laser beam reflected by the first mirror and reflects laser beam having first wavelength and contained in the received laser beam toward the first mirror; and

a wavelength conversion element disposed between the first mirror and the second mirror and converts at least a part of S-polarized light with respect to the first mirror contained in the received first wavelength laser beam into laser beam having second wavelength,

wherein:

the wavelength conversion element includes a plurality of wavelength conversion element pieces having polarization inversion axis and containing cyclic polarization inverted structure in a cyclic direction orthogonal to the polarization inversion axis, the wavelength conversion element pieces being affixed to one another in a direction along the polarization inversion axis; and

the polarization inversion axis is disposed parallel with the oscillation direction of the S-polarized light.

2. The laser source device according to claim 1 , wherein:

the first mirror, the second mirror, and the wavelength conversion element are provided as common units for a plurality of the arranged light emission units; and

the optical axis directions of laser beams emitted from the plural light emission units are disposed parallel with the surface of the first mirror.

3. The laser source device according to claim 1 , wherein the wavelength conversion element is produced by affixing the plural wavelength conversion element pieces to one another via spacers.

4. The laser source device according to claim 3 , wherein:

the linear expansion coefficient of the plural wavelength conversion element pieces of the wavelength conversion element is substantially equal to the linear expansion coefficient of the spacers of the wavelength conversion element; and

the thermal conductivity of the spacers is equal to or larger than the thermal conductivity of the plural wavelength conversion element pieces.

5. The laser source device according to claim 3 , wherein the spacers are made of the same material as that of the plural wavelength conversion element pieces.

6. The laser source device according to claim 1 , wherein:

a reinforcing member is provided on the outer side of the wavelength conversion element piece disposed at the outermost position in the polarization inversion axis direction; and

the surfaces of the plural wavelength conversion element pieces orthogonal to the cyclic direction and the surface of the reinforcing member orthogonal to the cyclic direction are collectively polished.

7. A projector comprising:

the laser source device according to claim 1 ;

a light modulation device which modulates laser beam emitted from the laser source device; and

a projection device which projects laser beam modulated by the light modulation device.

8. A monitoring device comprising:

the laser source device according to claim 1 ; and

an image pickup device which obtains an image of a subject illuminated by the laser source device.