An illumination system, an illumination control method and a projection apparatus are provided. The illumination system includes a first laser light source providing a first laser beam, and a light splitting module. When the first laser beam is incident to the light splitting module, a first portion of the first laser beam penetrates through the light splitting module, a second portion is reflected by the light splitting module. In the first illumination mode, the first laser beam is incident to the first light splitting region to form a first proportion of the first portion and the second portion. In the second illumination mode, the first laser beam is incident to the first light splitting region to form a second proportion of the first portion and the second portion, wherein the first proportion and the second proportion are different.

A prism block includes a first prism having first, second and third surfaces, a second prism having a fourth surface parallel to the first surface, a fifth surface facing the second surface, and a sixth surface, a third prism having seventh and eight surfaces respectively facing the second and fifth surfaces, and an optical path separation coating disposed between the fifth and eighth surfaces. Illumination light incident on the third surface is reflected by the second surface, and is emitted from the first surface. Projection light incident on the first surface is emitted from the fourth surface. Imaging light incident on the fourth surface is reflected by the optical path separation coating, and is emitted from the sixth surface. A projection axis plane including optical paths of the illumination light and the projection light, and an imaging axis plane including an optical path of the imaging light intersect each other.

A prism block includes a first prism having first, second and third surfaces, a second prism having a fourth surface parallel to the first surface, a fifth surface facing the second surface, and a sixth surface, a third prism having seventh and eight surfaces respectively facing the second and fifth surfaces, and an optical path separation coating disposed between the fifth and eighth surfaces. Illumination light incident on the third surface is reflected by the second surface, and is emitted from the first surface. Projection light incident on the first surface is emitted from the fourth surface. Imaging light incident on the fourth surface is reflected by the optical path separation coating, and is emitted from the sixth surface. A projection axis plane including optical paths of the illumination light and the projection light, and an imaging axis plane including an optical path of the imaging light intersect each other.

In an electro-optical device, a first polarizing element, a first phase difference element, a transmissive liquid crystal panel, a second phase difference element, and a second polarizing element are sequentially arranged. Here, when a phase difference of the first phase difference element and the second phase difference element is λ/4, an influence of orientation disorder of liquid crystal molecules can be alleviated, but a contrast ratio is reduced. Therefore, when a wavelength of incident light is λ, a phase difference R of the first phase difference element and the second phase difference element satisfies the following condition that 0<R<λ/4, preferably λ/12<R<λ/6. For example, it is assumed that the phase difference R is λ/8.

A phosphor wheel device includes a motor having a rotation shaft, a phosphor wheel substrate attached to one end side of the rotation shaft, and a balancer fixed to the phosphor wheel substrate. The balancer has at least one opening that is open to an outside of the phosphor wheel device.

In a first period, an optical apparatus converts first light that exits out of a retardation film into light polarized in a first polarization direction and converts second light that exits out of the retardation film into light polarized in a second polarization direction, and in a second period, the optical apparatus converts the first light that exits out of the retardation film into light polarized in the second polarization direction and converts the second light that exits out of the retardation film into light polarized in the first polarization direction.

A light-source device includes an excitation light source; a wavelength conversion unit to convert at least some of first color light into second color light; a light mixing element including a rod integrator to mix at least one of the first color light and the second color light from the conversion unit; and an optical element on an optical path of the first color light and having a reflecting surface. A center of the first color light on the reflecting surface intersects with only one of a first light flux of the first color light incident on and a second light flux of the first color light emitted from the conversion unit. An angle formed by a projection straight line of the first color light incident on an incident aperture of the integrator and a predetermined axial line of the incident aperture of the integrator is smaller than 40°.

A light-source device includes an excitation light source; a wavelength conversion unit to convert at least some of first color light into second color light; a light mixing element including a rod integrator to mix at least one of the first color light and the second color light from the conversion unit; and an optical element on an optical path of the first color light and having a reflecting surface. A center of the first color light on the reflecting surface intersects with only one of a first light flux of the first color light incident on and a second light flux of the first color light emitted from the conversion unit. An angle formed by a projection straight line of the first color light incident on an incident aperture of the integrator and a predetermined axial line of the incident aperture of the integrator is smaller than 40°.

The light emitting device includes a substrate, and a laminated structure provided to the substrate, and including a plurality of columnar parts, wherein the columnar part includes a first semiconductor layer, a second semiconductor layer different in conductivity type from the first semiconductor layer, and a light emitting layer disposed between the first semiconductor layer and the second semiconductor layer, the laminated structure includes a third semiconductor layer which is connected to an opposite side to the substrate of the second semiconductor layer, and is same in conductivity type as the second semiconductor layer, the second semiconductor layer is disposed between the light emitting layer and the third semiconductor layer, the third semiconductor layer is provided with a recessed part, an opening of the recessed part is provided to a surface at an opposite side to the substrate side of the third semiconductor layer, and a diametrical size in a bottom of the recessed part is smaller than a diametrical size in the opening of the recessed part.

A light-source device includes an excitation light source; a wavelength conversion unit to convert at least some of first color light into second color light; a light mixing element including a rod integrator to mix at least one of the first color light and the second color light from the conversion unit; and an optical element on an optical path of the first color light and having a reflecting surface. A center of the first color light on the reflecting surface intersects with only one of a first light flux of the first color light incident on and a second light flux of the first color light emitted from the conversion unit. An angle formed by a projection straight line of the first color light incident on an incident aperture of the integrator and a predetermined axial line of the incident aperture of the integrator is smaller than 40°.