A cooling device of a projection display apparatus includes a first heat receiving unit including an opening that is rectangular. The first heat receiving unit includes a flow path part that forms the opening. An image display element of the projection display apparatus includes a first front face located in front of a reflective image display, a second front face parallel to the first front face and located behind and outside the first front face, and a first side face located between the first front face and the second front face. The first front face is inserted into the opening, and the flow path part is in contact with the first side face and the second front face via a heat conductive member. The flow path part includes a front face that is flush with or in front of the first front face of the image display element.

A cooling device of a projection display apparatus includes a first heat receiving unit including an opening that is rectangular. The first heat receiving unit includes a flow path part that forms the opening. An image display element of the projection display apparatus includes a first front face located in front of a reflective image display, a second front face parallel to the first front face and located behind and outside the first front face, and a first side face located between the first front face and the second front face. The first front face is inserted into the opening, and the flow path part is in contact with the first side face and the second front face via a heat conductive member. The flow path part includes a front face that is flush with or in front of the first front face of the image display element.

A light conversion device is disclosed. The light conversion device includes a substrate and a wavelength conversion element (111). The wavelength conversion element (111) includes an inorganic binder, such as sodium silicate. Also disclosed are phosphor wheels and light engines including such phosphor wheels. Further disclosed are high-power laser projection display systems comprising a laser having a power of from about 60 W and about 300 W and a light conversion device. The use of an inorganic binder permits high thermal stability at reasonable cost.

To provide an optical element capable of realizing an increase in color range of videos and an improvement in brightness of the videos, a light source device including the optical element, and a projector including the light source device. Provided is an optical element including: a first color conversion layer; a second color conversion layer; and a heat insulating layer, in which the heat insulating layer is disposed between the first color conversion layer and the second color conversion layer, a light source device including the optical element, and a projector including the light source device.

To provide an optical element capable of realizing an increase in color range of videos and an improvement in brightness of the videos, a light source device including the optical element, and a projector including the light source device. Provided is an optical element including: a first color conversion layer; a second color conversion layer; and a heat insulating layer, in which the heat insulating layer is disposed between the first color conversion layer and the second color conversion layer, a light source device including the optical element, and a projector including the light source device.

A projection device includes a housing, a projection module, a fan, and at least one stopper wall structure. The housing has an air inlet, a first air outlet, and at least one second air outlet. The fan has a wind outlet facing the first air outlet. One part of the projection module is located between the wind outlet and the first air outlet, and one part of a heat dissipating airflow provided by the fan flows from the wind outlet to the first air outlet. The stopper wall structure is connected to the fan, and the stopper wall structure and one part of the housing define at least one air guiding channel. The other part of the projection module is located in the air guiding channel, and the other part of the heat dissipating airflow is guided by the air guiding channel to flow toward the second air outlet.

A projection device includes a housing, a projection module, a fan, and at least one stopper wall structure. The housing has an air inlet, a first air outlet, and at least one second air outlet. The fan has a wind outlet facing the first air outlet. One part of the projection module is located between the wind outlet and the first air outlet, and one part of a heat dissipating airflow provided by the fan flows from the wind outlet to the first air outlet. The stopper wall structure is connected to the fan, and the stopper wall structure and one part of the housing define at least one air guiding channel. The other part of the projection module is located in the air guiding channel, and the other part of the heat dissipating airflow is guided by the air guiding channel to flow toward the second air outlet.

A wavelength conversion element according to the present disclosure includes a wavelength conversion layer having a first surface having a recessed part, and a plurality of air holes, and configured to be excited by light in a first wavelength band to thereby generate light in a second wavelength band different from the first wavelength band, a particle disposed in the recessed part, a light transmissive member disposed so as to cover the recessed part and the particle, a reflecting layer disposed so as to be opposed to the first surface of the wavelength conversion layer, and a base member disposed so as to be opposed to the reflecting layer.

An optical device is provided including a light-imaging component configured to focus light fed to the light-imaging component in at least one focusing spot, wherein the light fed includes at least one predefinable wavelength; and a conversion apparatus including at least one phosphor which is designed to convert light having the at least one predefinable wavelength into conversion light, wherein the conversion apparatus is arranged in such a way that the at least one phosphor is arranged in the focusing spot of the light-imaging component. The light-imaging component is configured to generate at least two focusing spots, and the conversion apparatus is arranged in such a way that the at least two focusing spots are positioned on the at least one phosphor.

Provided is a wavelength conversion member including a ceramic layer as a reflective layer and having excellent luminescence intensity and a light emitting device using the same. A wavelength conversion member 10 including: a first porous ceramic layer 1 having a porosity of 20% by volume or more; and a phosphor layer 2 formed on a principal surface 1a of the first porous ceramic layer 1.