An optical imaging system is described including first to sixth lenses sequentially disposed from an object side to an image side, and an image sensor configured to convert incident light reflected from a subject, having passed through the first to sixth lenses, into an electrical signal. One of the first to sixth lenses includes a spherical object-side surface and another of the first to sixth lenses includes corresponding aspherical object-side surfaces. The first to sixth lenses include corresponding aspherical image-side surfaces, and a lens of the first to sixth lenses that is closer to the object side than the one of the first to sixth lenses including the spherical object-side surface, has a highest refractive index among the first to sixth lenses.

A cemented lens may include a first lens and a second lens connected via an adhesive layer. The first lens may include a convex surface facing toward the second lens, and a first flange surrounding an outer circumference of the convex surface. The second lens may include a concave surface connected to the convex surface, and a second flange surrounding an outer circumference of the concave surface. One of the first and second flange may include a projection protruding toward an other of the first and second flange. The other of the first and second flange may include an opposed portion opposed to a side surface of the projection Ga is a distance between the convex surface and the concave surface, and Gb is a distance between the side surface and the opposed portion, and the following expression: Gb<Ga may be satisfied.

The imaging optical system consists of a first optical system and a second optical system in order from a magnified side. The second optical system forms an image on an image display surface as an intermediate image, and the first optical system forms the intermediate image on a magnified-side conjugate plane. A height of a principal ray of light having a maximum angle of view becomes maximum on a lens surface of the whole system on the most magnified side, among heights of principal rays of light having a maximum angle of view on respective lens surfaces. The imaging optical system satisfies predetermined conditional expressions.

A photographing optical lens assembly includes, in order from object side to image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element has positive refractive power. The second, third, fourth and fifth lens elements have refractive power. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the sixth lens element are both aspheric, and the image-side surface has at least one inflection point. The seventh lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the seventh lens element are both aspheric, and the image-side surface has at least one inflection point.

A photographing optical lens assembly includes, in order from object side to image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element has positive refractive power. The second, third, fourth and fifth lens elements have refractive power. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the sixth lens element are both aspheric, and the image-side surface has at least one inflection point. The seventh lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the seventh lens element are both aspheric, and the image-side surface has at least one inflection point.

An optical lens assembly includes five lens elements and provides a TTL/EFL < 1.0. In an embodiment, the focal length of the first lens element f1 < TTL/2, an air gap between first and second lens elements is smaller than half the second lens element thickness, an air gap between the third and fourth lens elements is greater than TTL/5 and an air gap between the fourth and fifth lens elements is smaller than about 1.5 times the fifth lens element thickness. All lens elements may be aspheric.

A photographing optical lens assembly includes, in order from object side to image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element has positive refractive power. The second, third, fourth and fifth lens elements have refractive power. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the sixth lens element are both aspheric, and the image-side surface has at least one inflection point. The seventh lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the seventh lens element are both aspheric, and the image-side surface has at least one inflection point.

A photographing optical lens assembly includes, in order from object side to image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element has positive refractive power. The second, third, fourth and fifth lens elements have refractive power. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the sixth lens element are both aspheric, and the image-side surface has at least one inflection point. The seventh lens element with refractive power has an image-side surface being concave in a paraxial region, wherein an object-side surface and the image-side surface of the seventh lens element are both aspheric, and the image-side surface has at least one inflection point.

A method for fabricating millimeter and sub-millimeter size lenses using a high viscosity curable liquid, such as epoxy. The method comprises dispensing a predetermined volume of the curable liquid onto a substrate. The curable liquid preferably has a viscosity higher than 100 cps. Additionally, to reduce spherical aberration, the curable liquid can be cured upside down to leverage the effects of gravity.

A projection lens adjustment module applicable to a projection lens is provided. The projection lens includes a first assembly and a second assembly. The projection lens adjustment module includes a flexible connection line, an adjusting element and a driving mechanism. The flexible connection line has a first end and a second end opposite to each other. The adjusting element is connected to the first end. The driving mechanism is connected to the second assembly and the second end. When the adjusting element drives the first end to move along a first direction thereby leading the second end to move along a second direction non-parallel to the first direction, the second end drives the second assembly to move along an optical axis direction of the projection lens relative to the first assembly through the driving mechanism.