An optical system includes, in order from an object side to an image side, a front unit of a positive refractive power, a diaphragm, and a rear unit of a positive refractive power. The front unit includes, in order from the object side to the image side, a positive lens L11, a positive lens L12, and a negative lens L13. The rear unit includes, in order from the object side to the image side, a negative lens L21, a positive lens L22, and a positive lens L23. A predetermined condition is satisfied.

An optical lens includes a first lens group with a positive refractive power, a second lens group with a positive refractive power and an aperture stop. The first lens group and the second lens group are arranged in order from a first side to a second side, and the aperture stop is disposed between the first lens group and the second lens group. A total number of lenses with refractive powers in the optical lens is less than four, and the optical lens includes at least two lenses having an index of refraction of greater than 1.7.

An optical lens includes a first lens group with a positive refractive power, a second lens group with a positive refractive power and an aperture stop. The first lens group and the second lens group are arranged in order from a first side to a second side, and the aperture stop is disposed between the first lens group and the second lens group. A total number of lenses with refractive powers in the optical lens is less than four, and the optical lens includes at least two lenses having an index of refraction of greater than 1.7.

Wide-angle optical functionality is beneficial for imaging and image projection devices. Conventionally, wide-angle operation is attained by a complicated assembly of optical elements. Recent advances have led to meta-surface lenses or meta-lenses, which are ultra-thin planar lenses with nanoantennas that control the phase, amplitude, and/or polarization of light. Here, we present a meta-lens capable of diffraction-limited focusing and imaging over an unprecedented >170 angular field of view (FOV). The lens is integrated on a one-piece flat substrate and includes an aperture on one side and a single meta-surface on the other side. The meta-surface corrects third-order Seidel aberrations, including coma, astigmatism, and field curvature. The meta-lens has a planar focal plane, which enables considerably simplified system architectures for imaging and projection. The meta-lens design is generic and can be readily adapted to different meta-atom geometries and wavelength ranges to meet diverse application demands.

A light blocking sheet having a central axis includes a central hole and a plurality of inner extended portions. The central axis passes through the central hole, which is enclosed by a hole inner surface. The hole inner surface has a first corresponding circle and a second corresponding circle, wherein a diameter of the first corresponding circle is greater than a diameter of the second corresponding circle. The inner extended portions are adjacent to and surround the central hole, wherein each of the inner extended portions is extended and tapered from the first corresponding circle towards the second corresponding circle and includes an inner surface, and the inner surface includes a line pair. The line pair includes two line sections, wherein one end of one line section thereof and one end of the other line section thereof are towards the second corresponding circle and approach to each other.

A light blocking sheet having a central axis includes a central hole and a plurality of inner extended portions. The central axis passes through the central hole, which is enclosed by a hole inner surface. The hole inner surface has a first corresponding circle and a second corresponding circle, wherein a diameter of the first corresponding circle is greater than a diameter of the second corresponding circle. The inner extended portions are adjacent to and surround the central hole, wherein each of the inner extended portions is extended and tapered from the first corresponding circle towards the second corresponding circle and includes an inner surface, and the inner surface includes a line pair. The line pair includes two line sections, wherein one end of one line section thereof and one end of the other line section thereof are towards the second corresponding circle and approach to each other.

The present disclosure provides a lens assembly. The lens assembly, includes at least one lens having a central part used for imaging and an edge part around the central part; and a shading unit in the at least one lens. The edge part depresses from an image side surface to an object side surface and forms a concave part for positioning the shading unit. In addition, the present disclosure further discloses a lens module including the lens assembly mentioned above.

The present invention relates to projection and schlieren optical measurement technology, and more particularly to an integrated projection-schlieren optical system. The system includes a parallel light source system, a first positive lens, a diaphragm, a second positive lens, an image sensor, a negative lens, a knife edge device and a sample stage. In the system, a projection telescopic optical system and a schlieren camera optical system are respectively formed through the combination of optical characteristics of two movable lenses, enabling the integration functions of the projection optical system and the schlieren optical system.

The present invention relates to projection and schlieren optical measurement technology, and more particularly to an integrated projection-schlieren optical system. The system includes a parallel light source system, a first positive lens, a diaphragm, a second positive lens, an image sensor, a negative lens, a knife edge device and a sample stage. In the system, a projection telescopic optical system and a schlieren camera optical system are respectively formed through the combination of optical characteristics of two movable lenses, enabling the integration functions of the projection optical system and the schlieren optical system.

The present disclosure pertains to the field of screen. It is an object of the present disclosure to provide a transmissive screen including a microlens array. The screen of the present disclosure further comprises an aperture array arranged on a surface opposite to the surface on which the microlens array is disposed. A light shielding portion of the aperture array is a metal film. The transmissive screen of the present disclosure can be used for a display.