Abstract: A projection lens includes a first lens group, a second lens group, and a third lens group. The first lens group is composed of a first lens. The first lens has a concave surface and a convex surface, and the concave surface of the first lens faces a reducing side of the projection lens. The second lens group has positive refractive power, and includes a second lens having positive refractive power and a third lens having negative refractive power. The second lens is a biconvex lens, and the third lens has a concave lens facing the reducing side. The third lens group is composed of a fourth lens, and the fourth lens has a convex surface facing a magnifying side of the projection lens. The first lens group, the second lens group, and the third lens group include at least two aspheric lenses.

Abstract: A lens module has a magnified side and a reduced side having an imaging surface. The lens module includes a first, a second, and a third lens groups having positive refractive powers respectively. The first lens group includes a first and a second lenses. A value calculated by dividing a distance between a center of a surface of the first lens facing the magnified side and the imaging surface by the effective focal length of the lens module is greater than or equal to 1 and smaller than or equal to 3. The second lens group located between the first lens group and the reduced side includes a third and a fourth lenses. The third lens group located between the second lens group and the reduced side includes a fifth lens. Refractive powers of the first to the fifth lenses are negative, positive, positive, negative and positive, respectively.

Abstract: A lens module has a magnified side and a reduced side having an imaging surface. The lens module includes a first, a second, and a third lens groups having positive refractive powers respectively. The first lens group includes a first and a second lenses. A value calculated by dividing a distance between a center of a surface of the first lens facing the magnified side and the imaging surface by the effective focal length of the lens module is greater than or equal to 1 and smaller than or equal to 3. The second lens group located between the first lens group and the reduced side includes a third and a fourth lenses. The third lens group located between the second lens group and the reduced side includes a fifth lens. Refractive powers of the first to the fifth lenses are negative, positive, positive, negative and positive, respectively.

Abstract: A projection lens includes a first lens group, a second lens group, and a third lens group. The first lens group is composed of a first lens. The first lens has a concave surface and a convex surface, and the concave surface of the first lens faces a reducing side of the projection lens. The second lens group has positive refractive power, and includes a second lens having positive refractive power and a third lens having negative refractive power. The second lens is a biconvex lens, and the third lens has a concave lens facing the reducing side. The third lens group is composed of a fourth lens, and the fourth lens has a convex surface facing a magnifying side of the projection lens. The first lens group, the second lens group, and the third lens group include at least two aspheric lenses.

Abstract: A lens module including a first lens group, a second lens group, a third lens group, and an aperture stop is provided. The first lens group disposed between a magnified side and a reduced side has a positive refractive power. The second lens group disposed between the first lens group and the reduced side has a negative refractive power. The third lens group disposed between the second lens group and the reduced side has a positive refractive power. The aperture stop is disposed between the first lens group and the second lens group. Additionally, the distance from a center of the second surface to a center of the third surface is L1, an effective focal length is f, and the lens module satisfies 0.4<L1/f<1.2.

Abstract: A fixed-focus lens includes a first, a second, and a third lens groups arranged in sequence from the enlarged side to the reduced side and having positive refractive powers. The first lens group includes a first, a second, and a third lenses from the enlarged side to the reduced side. The second lens group includes a fourth, a fifth, and a sixth lenses from the enlarged side to the reduced side. The third lens group includes a seventh lens. The lens of the first lens group closest to the enlarged side in the fixed-focus lens has a concave surface. The distance between the lens surface of the second lens group closest to the reduced side and the lens surface of the third lens group closest to the enlarged side is L1. The overall length of the fixed-focus lens is L. The fixed-focus lens satisfies 0.1<L1/L<0.5.

Abstract: A fixed-focus lens includes a first, a second, and a third lens groups arranged in sequence from the enlarged side to the reduced side and having positive refractive powers. The first lens group includes a first, a second, and a third lenses from the enlarged side to the reduced side. The second lens group includes a fourth, a fifth, and a sixth lenses from the enlarged side to the reduced side. The third lens group includes a seventh lens. The lens of the first lens group closest to the enlarged side in the fixed-focus lens has a concave surface. The distance between the lens surface of the second lens group closest to the reduced side and the lens surface of the third lens group closest to the enlarged side is L1. The overall length of the fixed-focus lens is L. The fixed-focus lens satisfies 0.1<L1/L<0.5.

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power. The first lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence and refractive powers thereof are negative, negative, negative and positive respectively. The first and second lenses are meniscus lenses and two surfaces of the second lens are aspheric surfaces. The third lens is a biconcave lens and the fourth lens is a biconvex lens. The second lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence and refractive powers thereof are positive, positive, positive, negative and positive respectively. A cemented doublet lens is composed of the seventh and eighth lenses. The ninth lens is a biconvex lens.

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power. The first lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence and refractive powers thereof are negative, negative, negative and positive respectively. The first and second lenses are meniscus lenses and two surfaces of the second lens are aspheric surfaces. The third lens is a biconcave lens and the fourth lens is a biconvex lens. The second lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence and refractive powers thereof are positive, positive, positive, negative and positive respectively. A cemented doublet lens is composed of the seventh and eighth lenses. The ninth lens is a biconvex lens.

Abstract: A brightness enhancement film having a light exit surface and multiple stripe prisms disposed opposite to the light exit surface is provided. The stripe prisms are parallel, each stripe prism has a light incident curved surface, a light reflective inclined surface and a flat surface, and the light incident curved surface is connected between the light reflective inclined surface and the flat surface. The light incident curved surface and the flat surface are opposite to the light reflective inclined surface. The light incident curved surface is an outward curved surface. Further, a light beam from the light incident curved surface is reflected to the light exit surface by the light reflective surface.