Optical element and illuminator and projection display device
The invention relates to a technique of providing illumination light having an even intensity, in order to make intensity of three illumination light with a simple structure. A second optical waveguide having a second incidence plane for second color light and a third optical waveguide having a third incidence plane for third color light are joined to a first optical waveguide having a first incidence plane for first optical light and an emergence plane opposed to the first incidence plane. A first dichroic filter that reflects the first color light and the third color light and transmits the second color light is formed on a joint surface between the first optical waveguide and the second waveguide. A second dichroic filter that reflects the first color light and the second color light and transmits the third color light is formed on a joint surface between the first optical waveguide and the third waveguide.
1. An optical element, comprising:
a first optical waveguide having a first incidence plane on which first color light is incident and an emergence plane opposed to the first incidence plane;
a second optical waveguide having a second incidence plane on which second color light is incident;
a third optical waveguide having a third incidence plane on which third color light is incident, the second optical waveguide and the third optical waveguide being joined to the first optical waveguide;
a first dichroic filter formed on a joint plane between the first optical waveguide and the second optical waveguide to reflect the first color light and the third color light and transmitting the second color light; and
a second dichroic filter formed on a joint plane between the first optical waveguide and the third optical waveguide to reflect the first color light and the second color light and transmitting the third color light;
the three color light being emerged from the emergence plane of the first optical waveguide.
2. The optical element according to claim 1 , the three incidence planes being arranged substantially on the same plane.
3. The optical element according to claim 1 , the first optical waveguide being a tapered optical waveguide in which the area of the emergence plane is larger than that of the first incidence plane.
4. An illuminator, comprising:
a first light source to emit first color light;
a second light source to emit second color light;
a third light source to emit third color light; and
the optical element according to claim 1 having the three incidence planes on which the respective color light is incident.
5. The illuminator according to claim 4 , the first color light being green light.
6. A projection display device, comprising:
the illuminator according to claim 4 ; and
a light modulator to modulate the color light emerged from the optical element.