Optical apparatus

1. An optical apparatus comprising:

a light source unit;

at least one first light modulation element;

an illumination optical system configured to illuminate the first light modulation element using light from the light source unit; and

a relay optical system configured to make conjugate with each other a predetermined surface on an optical path between the light source unit and the first light modulation element, and a surface of the first light modulation element,

wherein the relay optical system includes, in order from the predetermined surface to the first light modulation element, a first reflection surface having a positive power, a second reflection surface having a negative power, and a third reflection surface having a positive power,

wherein the relay optical system satisfies the following conditional expression:

1.05≤ R 2*(1/ R 1+1/ R 3)≤9.00; or

0.10≤ R 2*(1/ R 1+1/ R 3)≤0.95,

where R1 is a curvature radius of the first reflection surface, R2 is a curvature radius of the second reflection surface, and R3 is a curvature radius of the third reflection surface.

2. The optical apparatus according to claim 1 , wherein the relay optical system satisfies the following conditional expression:

0.70≤ R 1/ R 3≤1.30.

3. The optical apparatus according to claim 1 , wherein the relay optical system satisfies the following conditional expressions:

1.04≤ R 1/ Do and 1.04≤ R 3/ Di ; or

R 1/ Do≤ 0.96 and R 3/ Di≤ 0.96,

where Do is an air conversion distance from the predetermined surface to the first reflection surface, and Di is an air conversion distance from the third reflection surface to the first light modulation element.

4. The optical apparatus according to claim 1 , wherein the first light modulation element is an image display element in which a plurality of pixels include micro mirrors.

5. The optical apparatus according to claim 1 , further comprising a color separator configured to separate light according to a wavelength on an optical path between the third reflection surface and the first light modulation element.

6. The optical apparatus according to claim 5 , wherein the color separator includes a TIR prism.

7. The optical apparatus according to claim 1 , further comprising a second light modulation element disposed near the predetermined surface.

8. The optical apparatus according to claim 7 , wherein the second light modulation element includes an image display element in which a plurality of pixels include micro mirrors.

9. The optical apparatus according to claim 1 , wherein the predetermined surface is an internal surface of the illumination optical system.

10. The optical apparatus according to claim 1 , wherein the first reflection surface includes a reflection surface of a first mirror, a second reflection surface includes a reflection surface of a second mirror, and the third reflection surface includes a reflection surface of a third mirror.

11. The optical apparatus according to claim 10 , wherein the first mirror and the second mirror are integrated with each other.

12. The optical apparatus according to claim 1 , further comprising a projection optical system configured to project light from the first light modulation element onto a projection surface.

13. The optical apparatus according to claim 1 , wherein the optical apparatus is an image projection apparatus.