A Mid-Wave Infrared (MWIR) objective lens having an F # of 2.64 and a 33.6° angular field of view. It is deployed, with a focal plane and scanning system, on an airborne platform for remote sensing applications. Focal length is 9 inches, and the image is formed on a focal plane constituting CCD or CMOS with micro lenses. The lens has, from object to image, three optical element groups with a cold shield/aperture stop. Group 1 has a positive optical power and three optical elements; Group 2 has a positive optical power and four optical elements; Group 3 has a positive optical power and three optical elements. The objective lens is made of two Germanium and Silicon. The lens is both apochromatic and orthoscopic, and corrected for monochromatic and chromatic aberrations over 3.3 to 5.1 micrometers.

The imaging lens consists of, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group, and a third lens group. During focusing, the second lens group moves. The first lens group includes a first positive lens disposed to be closest to the object side, a second positive lens disposed closer to the image side than the first positive lens, and an LA lens disposed closer to the image side than the second positive lens. Assuming that a partial dispersion ratio and an Abbe number thereof are respectively θgFA and vA, the LA lens satisfies 0.02<θgFA+0.001618×vA−0.6415<0.1. The imaging lens satisfies predetermined conditional expressions.

The imaging lens consists of, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group, and a third lens group. During focusing, the second lens group moves. The first lens group includes a first positive lens disposed to be closest to the object side, a second positive lens disposed closer to the image side than the first positive lens, and an LA lens disposed closer to the image side than the second positive lens. Assuming that a partial dispersion ratio and an Abbe number thereof are respectively θgFA and vA, the LA lens satisfies 0.02<θgFA+0.001618×vA−0.6415<0.1. The imaging lens satisfies predetermined conditional expressions.

An imaging lens including an aperture stop, a first lens, a second lens and a third lens sequentially arranged along an optical axis from an object side to an image side is provided. The first lens is an aspheric glass lens and has positive refracting power. The second lens is an aspheric plastic lens. The third lens is an aspheric plastic lens. The imaging lens has the transmittance higher than 85% for light with a wavelength of 940 nm and has the field of view less than 90 degrees.

An optical system includes a front lens group consisting of at least one lens unit that moves during focusing and having a positive refractive power, and a rear lens group consisting of a lens unit that is immobile during focusing and having a negative refractive power. The rear lens group includes at least two negative lenses and one positive lens. The front lens group and the rear lens group satisfy a predetermined inequality.

An optical system includes a front lens group consisting of at least one lens unit that moves during focusing and having a positive refractive power, and a rear lens group consisting of a lens unit that is immobile during focusing and having a negative refractive power. The rear lens group includes at least two negative lenses and one positive lens. The front lens group and the rear lens group satisfy a predetermined inequality.

An imaging optical system includes three lens elements. The three lens elements, in order from an object side to an image side, are a first lens element having an object-side surface facing the object side and an image-side surface facing the image side, a second lens element having an object-side surface facing the object side and an image-side surface facing the image side, and a third lens element having an object-side surface facing the object side and an image-side surface facing the image side. The third lens element has positive refractive power, the imaging optical system has a total of three lens elements, and there are air gaps between paraxial regions of the first lens element, the second lens element and the third lens element.

An imaging lens consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a positive refractive power; and a third lens group, wherein: during focusing, the second lens group moves along an optical axis, and the first lens group and the third lens group remain stationary with respect to an image plane, the second lens group includes a stop, an Lp1 lens, which is a positive lens, is disposed closest to the object side in the second lens group, an Lp2 lens, which is a positive lens, is disposed closest to the image side in the second lens group.

An imaging lens consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a positive refractive power; and a third lens group, wherein: during focusing, the second lens group moves along an optical axis, and the first lens group and the third lens group remain stationary with respect to an image plane, the second lens group includes a stop, an Lp1 lens, which is a positive lens, is disposed closest to the object side in the second lens group, an Lp2 lens, which is a positive lens, is disposed closest to the image side in the second lens group.

An augmented reality display system including an input unit, an operation processing unit and an output unit is provided. The input unit is configured to obtain an environment information. The operation processing unit is configured to operate and process the environment information provided by the input unit to generate an output information. The output unit is configured to transmit the output information provided by the operation processing unit to a user. The output unit includes at least one display module. The at least one display module includes a transparent display, a first lens having a negative refractive power, a second lens having a negative refractive power and a third lens having a positive refractive power arranged in sequence from a display side to an eye side. An augmented reality display method is also provided.