A light-emitting device includes an optical amplifier and gives off output light from optical amplifier by making a plurality of seed light rays, having mutually different wavelengths, incident on optical amplifier. Optical amplifier includes a medium portion containing a wavelength-converting element. Optical amplifier has wavelength-converting element thereof excited by excitation light to produce a plurality of partially coherent light rays, of which wavelengths are respectively the same as the mutually different wavelengths of plurality of seed light rays, thereby giving off, as output light, a multi-wavelength light beam. Excitation light has a shorter wavelength than any of plurality of seed light rays and is incident on the medium portion. Multi-wavelength light beam includes a plurality of light rays amplified. Plurality of light rays amplified have wavelengths, which are respectively the same as mutually different wavelengths of plurality of seed light rays.

A flashlight, including: a lens assembly having an adjusting lens; and a light source assembly provided at one side of the lens assembly, the light source assembly comprising a first light source, a second light source, an excitation element, and a light path adjusting element. Light emitted from the first light source irradiates the excitation element to generate first exciting light, and light emitted from the second light source irradiates the excitation element to generate second exciting light. The first exciting light and the second exciting light sequentially pass through the light path adjusting element and the adjusting lens and then are outputted in parallel. The flashlight can integrate the advantages of the first light source and the second light source, to provide the light source with excellent light emitting performance.

Provided is a projection device and projection system that includes a first light source which emits a first light beam, a diffraction part on which first predetermined pattern is provided, and the diffraction part diffracts at least a part of the first light beam emitted from the first light source to form first pattern corresponding to the first predetermined pattern, and a reflection part on which one or more second predetermined patterns are provided, the reflection part reflects a second light beam incident thereon to form second pattern corresponding to the one or more second predetermined patterns, and one of the first pattern and the second pattern forms projection pattern or both of the first pattern and the second pattern are superposed to form projection pattern.

The present disclosure discloses a lamp for projecting a nebula and a starry sky comprising a housing, a light source assembly, a laser assembly, a rotating assembly, a control board, a base seat, and a power source port. The light source assembly and the laser assembly are disposed in the housing and penetrate through the housing, and the rotating assembly and the control board are disposed in the housing. The rotating assembly is configured to drive a rotating optical sheet and a diffraction sheet to rotate. The light source assembly comprises a light source board, a light reflecting cup, the rotating optical sheet, and a lens assembly having a frosted surface with an array of protrusions. The light source board, the light reflecting cup, the rotating optical sheet, and the lens assembly are successively disposed along a path in which light rays emitted by the light source board move.

A laser-based light source includes a material arranged on a package base adjacent to a laser diode chip and an optical element coupled to the material. The optical element is aligned to receive electromagnetic radiation from the laser diode chip. The optical element includes a wavelength conversion material and is configured to receive at least a portion of the electromagnetic radiation emitted by the laser diode chip. A reflective material surrounds sides of the optical element.

A photoconversion device includes a wavelength converter including a plurality of phosphor areas, a drive, and a controller. The plurality of phosphor areas includes a first phosphor area to emit fluorescence with a first wavelength spectrum in response to excitation light and a second phosphor area to emit fluorescence with a second wavelength spectrum different from the first wavelength spectrum in response to the excitation light. The drive changes an illuminating area to receive the excitation light in the plurality of phosphor areas. The controller drives the drive to change the illuminating area in the plurality of phosphor areas and stop driving the drive to define the illuminating area in the plurality of phosphor areas.

One aspect of the disclosure provides an optical wavelength conversion member including a polycrystalline ceramic sintered body containing, as main components, Al.sub.2O.sub.3 crystal grains and crystal grains represented by formula (Y,A).sub.3B.sub.5O.sub.12:Ce. In the optical wavelength conversion member, a (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain has a region wherein the A concentration of a peripheral portion of the (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain is higher than that of an interior portion of the (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain. Thus, the optical wavelength conversion member exhibits high fluorescence intensity (i.e., high emission intensity) and high heat resistance (i.e., low likelihood of temperature quenching). The optical wavelength conversion member has a structure wherein the element A concentration of a peripheral portion of a (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain differs from that in an interior portion of the crystal grain. This structure can achieve a ceramic fluorescent body exhibiting superior fluorescent characteristics and superior thermal characteristics with varied colors of emitted light.

A light source device includes a light source device includes a first light source configured to emit first light, and a first lens that includes a first surface on which the first light having a first optical axis is incident and a second surface from which a second light having a second optical axis is emitted. An intensity of the first light has a first value on the first optical axis of the first light.

The invention provides a light generating device (1000) comprising (i) a plurality of n light sources (100), and (ii) an optical component (1200) comprising an array (200) of prismatic elements (300), wherein: (a) the plurality of n light sources (100) comprise a first subset of one or more first light sources (110) configured to generate collimated first light source light (111) and a second subset of one or more second light sources (120) configured to generate collimated second light source light (121), wherein n>2; (b) the array (200) of prismatic elements (300) is configured in a light receiving relationship with the n light sources (100), wherein the array of prismatic elements (300) comprises k 1 parallel arranged first prismatic faces (201) and k2 parallel arranged second prismatic faces (202), wherein k1>2 and wherein k2>2, wherein the first prismatic faces (201) and the second prismatic faces (202) are not mutually parallel; (c) the first light sources (110) are configured to irradiate the first prismatic faces (201) and the second light sources (120) are configured to irradiate the second prismatic faces (202); and (d) the prismatic elements (300) are configured to reflect or refract the collimated first light source light (111) and the collimated second light source light (121) as coincident beams of first light source light (111) and second light source light (121).

[Object] To provide a light source device, a headlight, a display apparatus, and an illumination apparatus having excellent heat dissipation. [Solving Means] 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.