Abstract: A light source device, including a first light source, providing a first light beam in a first time period of a first period; and a second light source, providing a second light beam in a second time period of the first period, is provided. The first light beam and the second light beam have the same color temperature. The first light beam and the second light beam are emitted alternately in the first period, and a color rendering index of mixed light of the first light beam and the second light beam is greater than or equal to 85.

Abstract: An optical lens includes a first lens group, a second lens group and an aperture stop. The first lens group includes three lenses with refractive powers. The second lens group has a positive refractive power and includes two lenses with refractive power. The aperture stop is disposed between the first lens group and the second lens group. The optical lens satisfies the conditions of 2 mm<DL<6 mm, LT<15 mm and 0.2<DL/LT<0.38, where DL is a diameter of a lens surface of the second lens group furthest from the first lens group, and LT is a length measured on the optical axis between two outermost lens surfaces of the optical lens.

Abstract: The disclosure provides a projection lens including a first lens set and a second lens set disposed sequentially from a magnified side to a reduced side. The first lens set and the second lens set are separated by a minimum inner diameter of a lens barrel. The first lens set includes 4 to 6 spherical lenses, and a refractive power of the first lens set is negative. The second lens set includes 4 to 6 lenses, where one of the lenses is an aspheric lens, and a refractive power of the second lens set is positive. A transmittance of the projection lens at a wavelength of 365 nm is greater than or equal to 75%.

Abstract: An optical lens includes a first lens group, a second lens group and an aperture stop disposed between the first lens group and the second lens group. The optical lens satisfies the conditions of 7 mm<D<25 mm and 0.3<D/LT<0.5, where D is a diameter of a lens surface of the second lens group furthest from the first lens group and LT is a total lens length measured along an optical axis between a lens surface of the first lens group furthest from the second lens group and the lens surface of the second lens group furthest from the first lens group.

Abstract: A lens assembly including a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, arranged from the magnification side to the reduction side, is provided. The fourth lens and the fifth lens are combined into a cemented lens having an aspherical surface. The lens assembly includes 5 to 6 lenses with a refractive power. The first lens is a glass lens, and the others are aspherical lenses. R1 is the radius of curvature of the lens surface of the first lens facing the magnification side, R2 is the radius of curvature of the lens surface of the first lens facing the reduction side, T is the thickness, on the optical axis of the lens assembly, of the first lens, wherein the refractive index of the first lens>1.55, the Abbe number of the first lens>55, and R1-R2-T<8.8.

Abstract: A projection lens includes a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, a sixth, and a concave mirror sequentially arranged from a minified side to a magnified side. An outer diameter of the second lens is less than an outer diameter of the first lens. An outer diameter of the fifth lens is greater than that of the fourth lens. An outer diameter of the sixth lens is less than that of the fifth lens. The first lens, the second lens, the aperture stop, and the third lens are fixed relative to the concave mirror and the fourth lens is capable of moving along an optical axis relative to the concave mirror when the projection lens is in focusing. The projection lens includes 9 to 30 lenses with refractive power. A projector using said projection lens is also provided.

Abstract: A projection lens includes a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, a sixth, and a concave mirror sequentially arranged from a minified side to a magnified side. An outer diameter of the second lens is less than an outer diameter of the first lens. An outer diameter of the fifth lens is greater than that of the fourth lens. An outer diameter of the sixth lens is less than that of the fifth lens. The first lens, the second lens, the aperture stop, and the third lens are fixed relative to the concave mirror and the fourth lens is capable of moving along an optical axis relative to the concave mirror when the projection lens is in focusing. The projection lens includes 9 to 30 lenses with refractive power. A projector using said projection lens is also provided.

Abstract: An optical lens includes two lens groups and an aperture stop. A total number of lenses with refractive power of the two lens groups is larger than three, and the two lens groups includes an aspheric lens with negative refractive power. The aperture stop is disposed between the two lens groups. The optical lens satisfies the following condition: 0.05>[y(?)?(EFL*sin ?)]/(EFL*sin ?)>?0.3, where ? denotes a half field of view, y(?) denotes an image height of an image plane for visible light with respect to the half field of view ?, and EFL denotes an effective focal length for visible light of the optical lens.

Abstract: An optical lens includes a first lens group, a second lens group and an aperture stop. The first lens group includes three lenses with refractive powers. The second lens group has a positive refractive power and includes two lenses with refractive power. The aperture stop is disposed between the first lens group and the second lens group. The optical lens satisfies the conditions of 2 mm<DL<6 mm, LT<15 mm and 0.2<DL/LT<0.38, where DL is a diameter of a lens surface of the second lens group furthest from the first lens group, and LT is a length measured on the optical axis between two outermost lens surfaces of the optical lens.

Abstract: A lens assembly including a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, arranged from the magnification side to the reduction side, is provided. The fourth lens and the fifth lens are combined into a cemented lens having an aspherical surface. The lens assembly includes 5 to 6 lenses with a refractive power. The first lens is a glass lens, and the others are aspherical lenses. R1 is the radius of curvature of the lens surface of the first lens facing the magnification side, R2 is the radius of curvature of the lens surface of the first lens facing the reduction side, T is the thickness, on the optical axis of the lens assembly, of the first lens, wherein the refractive index of the first lens>1.55, the Abbe number of the first lens>55, and R1-R2-T<8.8.

Abstract: An optical lens includes a first lens group and a second lens group. The first lens group is disposed between a magnified side and a minified side and has a negative refractive power. The second lens group is disposed between the first lens group and the minified side and has a positive refractive power. The optical lens is capable of forming an image at the magnified side. 0.52>F/H>0.46, where F is an effective focal length, and H is an image height.

Abstract: A lens including a first lens group and a second lens group is provided. The first lens group is disposed between a magnified side and a minified side. The second lens group is disposed between the first lens group and the minified side. The lens includes six or less lens elements, and at least four of the six or less lens elements are aspheric lenses. A field of view of the lens is in a range between 100 degrees and 165 degrees, and the second lens group has at least one spherical lens.

Abstract: An optical lens includes a first lens group with a negative refractive power, a second lens group with a positive refractive power, and an aperture stop disposed between the first lens group and the second lens group. The second lens group is disposed between the first lens group and the second side. The optical lens satisfies the conditions: 2.1<D1/D3<3.0 and 1.9<D1/DL<3.2, where D1 is a diameter of a surface of the first lens facing the first side, D3 is a diameter of a surface of the third lens facing the first side, DL is a diameter of a surface of a last lens facing the second side, and the last lens is nearest the second side as compared with any other lens of the optical lens.

Abstract: An optical lens includes a first lens group, a second lens group and an aperture stop disposed between the first lens group and the second lens group. The optical lens satisfies the conditions of 7 mm<D<25 mm and 0.3<D/LT<0.5, where D is a diameter of a lens surface of the second lens group furthest from the first lens group and LT is a total lens length measured along an optical axis between a lens surface of the first lens group furthest from the second lens group and the lens surface of the second lens group furthest from the first lens group.

Abstract: An optical lens includes a first lens group with a negative refractive power, a second lens group with a positive refractive power, and an aperture stop disposed between the first lens group and the second lens group. The second lens group is disposed between the first lens group and the second side. The optical lens satisfies the conditions: 2.1<D1/D3<3.0 and 1.9<D1/DL<3.2, where D1 is a diameter of a surface of the first lens facing the first side, D3 is a diameter of a surface of the third lens facing the first side, DL is a diameter of a surface of a last lens facing the second side, and the last lens is nearest the second side as compared with any other lens of the optical lens.

Abstract: A lens including a first lens group and a second lens group is provided. The first lens group is disposed between a magnified side and a minified side. The second lens group is disposed between the first lens group and the minified side. The lens includes six or less lens elements, and at least four of the six or less lens elements are aspheric lenses. A field of view of the lens is in a range between 100 degrees and 165 degrees, and the second lens group has at least one spherical lens.

Abstract: One embodiment of the invention discloses an optical imaging device including an optical lens. The optical lens has N number of lenses, and the N number of lenses are divided into a first lens group and a second lens group and have at least three aspheric lenses. The first lens group is disposed between an object side and an image side, and the first lens group has (N/2)?1 piece of lens. The first lens group includes, in order from the object side, a first lens, a second lens and a third lens, and the second lens is an aspheric lens. The second lens group is disposed between the first lens group and the image side, and an aperture stop is disposed between the first lens group and the second lens group.

Abstract: An optical lens includes two lens groups and an aperture stop. A total number of lenses with refractive power of the two lens groups is larger than three, and the two lens groups includes an aspheric lens with negative refractive power. The aperture stop is disposed between the two lens groups. The optical lens satisfies the following condition: 0.05>[y(?)?(EFL*sin ?)]/(EFL*sin ?)>?0.3, where ? denotes a half field of view, y(?) denotes an image height of an image plane for visible light with respect to the half field of view ?, and EFL denotes an effective focal length for visible light of the optical lens.

Abstract: One embodiment of the invention discloses an optical imaging device including an optical lens. The optical lens has N number of lenses, and the N number of lenses are divided into a first lens group and a second lens group and have at least three aspheric lenses. The first lens group is disposed between an object side and an image side, and the first lens group has (N/2)?1 piece of lens. The first lens group includes, in order from the object side, a first lens, a second lens and a third lens, and the second lens is an aspheric lens. The second lens group is disposed between the first lens group and the image side, and an aperture stop is disposed between the first lens group and the second lens group.

Abstract: An image pickup apparatus includes a lens, an image sensor, an optical filter, and a driving device. The lens focuses light beams from at least one subject to form an optical image, and the image sensor receives the optical image and converts the optical image into at least one electric signal. The optical filter includes a first plate and a second plate, the first plate is disposed between the lens and the image sensor, and the second plate is disposed between the first plate and the image sensor. The driving device moves the second plate. The second plate has substantially the same index of refraction as the first plate, and a thickness of the second plate is continuously decreased or increased across the second plate.