Optical imaging device

An optical imaging system comprising:

• a lens group comprising a plurality of lenses disposed in order along an optical axis;
• an optical path folding member disposed on an object side of the lens group;
• and
• a first reflection member and a second reflection member, disposed between the optical path folding member and the lens group, each having a freeform surface,
• wherein 1.40<f/fL<1.80,
• where f is a focal length of the optical imaging system, and fL is a focal length of the lens group.

An optical imaging system, comprising:

• a reflection element, disposed between a lens group and an optical path folding member, and configured to bend an optical path between the optical path folding member and the lens group,
• wherein the reflection element comprises a first reflection member having positive refractive power and a second reflection member having negative refractive power,
• wherein the lens group comprises a first lens having positive refractive power, and a second lens having a concave image-side surface, and
• wherein the lens group comprises a total of five lenses.

An optical imaging system, comprising:

• a first lens, a second lens, a third lens, a fourth lens, and a fifth lens disposed in order from an object side toward an imaging plane;
• and
• a first reflection member and a second reflection member, disposed on an object side of the first lens, each having a freeform surface,
• wherein the second lens has a concave object-side surface, and
• wherein the optical imaging system includes a total of five lenses.