Abstract: A cooling device, a light-source device, an image projection apparatus, and a wavelength converter. The cooling device includes a housing having a storage space, the storage space storing a heater and a base on which the heater is disposed, a heatsink at least partially disposed in the storage space and thermally connected to a space outside the storage space to dissipate heat generated by the heater to outside of the storage space, and an airflow path forming member covering at least some of the heatsink and forming a path for the heatsink to receive air flow absorbing the heat generated by the heater. In the cooling device, the heater or the base at least partially protruding from the airflow path member when the airflow path member is viewed in a direction orthogonal to a face of the heater on which light strikes.

Abstract: An image projection apparatus includes a light source module including a light source to emit excitation light, a pair of phosphor wheels, a light mixing element, an optical system to guide the excitation light emitted from the light source to the pair of phosphor wheels, and combine a pair of fluorescent lights emitted from the pair of phosphor wheels and guide combined fluorescent light to the light mixing element, an optical casing hermetically sealing the optical system, a first cooling casing hermetically sealing one of the phosphor wheels and having a first airflow circulation path, and a second cooling casing hermetically sealing another one of the pair of phosphor wheels and having a second airflow circulation path, an optical modulation element to modulate the light emitted from the light mixing element, and a projection optical system to project the light modulated by the optical modulation element onto a display device.

Abstract: An image projection apparatus includes a projection optical system configured to project an image with light emitted from a light source; a photodetector, and circuitry. The photodetector is configured to detect an amount of first light out of the light emitted from the light source and does not enter the projection optical system, and an amount of second light out of the light emitted from the light source and has passed through the projection optical system. The circuitry is configured to compare the amount of first light and the amount of second light, and control a notification device to perform a notification operation in response to reception of a comparison result that a difference in the amount of first light and the amount of second light is equal to or greater than a threshold.

Abstract: An image projection apparatus includes a projection optical system configured to project an image with light emitted from a light source; a photodetector, and circuitry. The photodetector is configured to detect an amount of first light out of the light emitted from the light source and does not enter the projection optical system, and an amount of second light out of the light emitted from the light source and has passed through the projection optical system. The circuitry is configured to compare the amount of first light and the amount of second light, and control a notification device to perform a notification operation in response to reception of a comparison result that a difference in the amount of first light and the amount of second light is equal to or greater than a threshold.

Abstract: A lighting apparatus to focus light emitted from a light source onto an image generation element includes a light equalizer to receive the light emitted from the light source, equalize the received light by reflecting the received light on an inner face of the light equalizer, and exit the equalized light, and a light detector disposed near the light equalizer to detect light intensity of leak light leaked from the light equalizer.

Abstract: A disclosed projection optical apparatus includes a plurality of lenses, each of the lenses having a flat surface in a part of an outer circumference; a lens holder having a hollow cylindrical shape and configured to hold the lenses; and a vent hole formed of gaps communicating between the flat surfaces of the lenses and the lens holder.

Abstract: A lighting apparatus to focus light emitted from a light source onto an image generation element includes a light equalizer to receive the light emitted from the light source, equalize the received light by reflecting the received light on an inner face of the light equalizer, and exit the equalized light, and a light detector disposed near the light equalizer to detect light intensity of leak light leaked from the light equalizer.

Abstract: A disclosed projection optical apparatus includes a plurality of lenses, each of the lenses having a flat surface in a part of an outer circumference; a lens holder having a hollow cylindrical shape and configured to hold the lenses; and a vent hole formed of gaps communicating between the flat surfaces of the lenses and the lens holder.

Abstract: A projection optical apparatus projects an image generated by an image generator onto a projection face by passing the image through a plurality of optical elements and an exit window. The projection optical apparatus includes an invisible-light reduction device to cut invisible light. The invisible-light reduction device prevents intrusion of the invisible light into the projection optical apparatus.