An optical lens system includes two lens elements which are, in order from an object side to an image side along an optical path: a first lens element and a second lens element. Each of the two lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. At least one of the object-side surface and the image-side surface of at least one lens element of the optical lens system is aspheric. A total number of the lens elements in the optical lens system is two.

An optical lens system includes two lens elements which are, in order from an object side to an image side along an optical path: a first lens element and a second lens element. Each of the two lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. At least one of the object-side surface and the image-side surface of at least one lens element of the optical lens system is aspheric. A total number of the lens elements in the optical lens system is two.

An imaging device capable of a rotation in a predetermined direction includes a first lens unit having a first optical axis and a first focal length, a first imaging unit to image light passing through the first lens unit; a second lens unit having a second optical axis and a second focal length shorter than the first focal length, a second imaging unit to image light passing through the second lens unit, a dome shaped protection cover disposed on a subject side of the first and the second lens unit and protect the first and the second lens unit, and a support unit for supporting the first and the second lens unit so that an angle at which the first optical axis intersects an inner surface of the protection cover is closer to a vertical angle than an angle at which the second optical axis intersects the inner surface of the protection cover.

An imaging device capable of a rotation in a predetermined direction includes a first lens unit having a first optical axis and a first focal length, a first imaging unit to image light passing through the first lens unit; a second lens unit having a second optical axis and a second focal length shorter than the first focal length, a second imaging unit to image light passing through the second lens unit, a dome shaped protection cover disposed on a subject side of the first and the second lens unit and protect the first and the second lens unit, and a support unit for supporting the first and the second lens unit so that an angle at which the first optical axis intersects an inner surface of the protection cover is closer to a vertical angle than an angle at which the second optical axis intersects the inner surface of the protection cover.

An optical system and a projection device are provided. The optical system includes a display unit, a first lens group, a second lens group, and a reflector in sequence along a transmission direction of light; both the first lens group and the second lens group have positive focal powers; the optical system satisfies the following relationship: 0.01≤|φ.sub.100|≤0.02 and 0.005≤|.sub.φ200|≤0.015; φ.sub.100 represents a focal power of the first lens group, and φ.sub.200 represents a focal power of the second lens group.

An optical system and a projection device are provided. The optical system includes a display unit, a first lens group, a second lens group, and a reflector in sequence along a transmission direction of light; both the first lens group and the second lens group have positive focal powers; the optical system satisfies the following relationship: 0.01≤|φ.sub.100|≤0.02 and 0.005≤|.sub.φ200|≤0.015; φ.sub.100 represents a focal power of the first lens group, and φ.sub.200 represents a focal power of the second lens group.

A lens apparatus includes an imaging optical system includes an imaging optical system including a plurality of lenses, a first holding member holding at least a first lens closest to an object among the plurality of lenses, and configured to move in an optical axis direction of the imaging optical system to perform focusing, a barrel member provided on an outside of the first holding member, and a control unit configured to control a driving unit configured to move the first holding member. When focus is at infinity, an edge surface on an object side of the barrel member is positioned on the object side of a surface vertex of an object-side surface of the first lens. When focus is at infinity, an edge surface on the object side of the control unit is positioned on the object side of the surface vertex.

Implementations of an augmented reality (AR)-capable display device for displaying light generated by a display onto a predefined field of view are disclosed herein. Within one implementation, the display device comprises a mount assembly configured to removably attach with a mobile computing device associated with the display, to thereby arrange the display with a predefined position. The display device further comprises an optical arrangement having a predefined arrangement relative to the predefined position and defining the field of view. The optical arrangement comprises a first mirror element configured to reflect a first portion of first incident light that is based on the light generated by the display, and a second mirror element disposed within the field of view and configured to reflect, onto the field of view, a second portion of second incident light that is based on the first portion.

Implementations of an augmented reality (AR)-capable display device for displaying light generated by a display onto a predefined field of view are disclosed herein. Within one implementation, the display device comprises a mount assembly configured to removably attach with a mobile computing device associated with the display, to thereby arrange the display with a predefined position. The display device further comprises an optical arrangement having a predefined arrangement relative to the predefined position and defining the field of view. The optical arrangement comprises a first mirror element configured to reflect a first portion of first incident light that is based on the light generated by the display, and a second mirror element disposed within the field of view and configured to reflect, onto the field of view, a second portion of second incident light that is based on the first portion.

An imaging lens system includes a first group having positive power and a second group having positive power disposed in that order from an object side to an image. The first group includes a first sub-group and a second sub-group. The second group includes a third sub-group, a stop, and a fourth sub-group. Conditional expressions (1), (2), and (3) below are satisfied:
0.07<f2/f1<0.4  (1);
0.45<f2/f2a<0.7  (2); and
1.05<f/R1aN<1.55  (3) where f denotes a focal length of an entirety of the imaging lens system focused at infinity, f1 denotes a focal length of the first group, f2 denotes a focal length of the second group focused at infinity, f2a denotes a focal length of the third sub-group focused at infinity, and R1aN denotes a radius of curvature of a surface closest to the image side within the first sub-group.