Abstract: There is provided a light source device, a headlight, a display apparatus, and an illumination apparatus having excellent heat dissipation. The light source device includes a substrate, a phosphor, a light emitting element, and a wavelength-selective reflecting member. The phosphor is disposed in contact with the substrate. The light emitting element emits excitation light for exciting the phosphor. The wavelength-selective reflecting member partially reflects the excitation light emitted from the light emitting element to be guided to the phosphor and transmits fluorescence emitted from the phosphor by excitation caused by incidence of the excitation light and the excitation light reflected by the phosphor.

Abstract: An optical element including a first groove extending from first end of the outer peripheral face in an optical axis direction towards second end, and a second groove connected to the first groove and extending from second end of the outer peripheral face in the optical axis direction towards first end; and a position-adjusting concave part which is between the first and second grooves and adjusts positions by adjusting member in the optical axis direction, a revolving direction about the optical axis, a width direction of first and second grooves, which is orthogonal to the optical axis, and in a synthesized direction that is a combination of at least two of those directions, wherein the optical element is molded by using only a first molding die for molding a part on the first groove side and a second molding die for molding a part on the second groove side.

Abstract: An optical element including a first groove extending from first end of the outer peripheral face in an optical axis direction towards second end, and a second groove connected to the first groove and extending from second end of the outer peripheral face in the optical axis direction towards first end; and a position-adjusting concave part which is between the first and second grooves and adjusts positions by adjusting member in the optical axis direction, a revolving direction about the optical axis, a width direction of first and second grooves, which is orthogonal to the optical axis, and in a synthesized direction that is a combination of at least two of those directions, wherein the optical element is molded by using only a first molding die for molding a part on the first groove side and a second molding die for molding a part on the second groove side.

Abstract: An optical element including a first groove extending from first end of the outer peripheral face in an optical axis direction towards second end, and a second groove connected to the first groove and extending from second end of the outer peripheral face in the optical axis direction towards first end; and a position-adjusting concave part which is between the first and second grooves and adjusts positions by adjusting member in the optical axis direction, a revolving direction about the optical axis, a width direction of first and second grooves, which is orthogonal to the optical axis, and in a synthesized direction that is a combination of at least two of those directions, wherein the optical element is molded by using only a first molding die for molding a part on the first groove side and a second molding die for molding a part on the second groove side.

Abstract: An optical element including a first groove extending from first end of the outer peripheral face in an optical axis direction towards second end, and a second groove connected to the first groove and extending from second end of the outer peripheral face in the optical axis direction towards first end; and a position-adjusting concave part which is between the first and second grooves and adjusts positions by adjusting member in the optical axis direction, a revolving direction about the optical axis, a width direction of first and second grooves, which is orthogonal to the optical axis, and in a synthesized direction that is a combination of at least two of those directions, wherein the optical element is molded by using only a first molding die for molding a part on the first groove side and a second molding die for molding a part on the second groove side.