A vehicle projection lens includes a plastic aspheric first lens, an aperture stop, a cemented lens consisting of a glass second lens and a glass third lens, and a glass fourth lens arranged in order from a magnified side to a minified side. An F-number of the vehicle projection lens is smaller than or equal to 0.8, and the vehicle projection lens consists essentially of four lenses respectively with positive, positive, negative and positive refractive powers.

A vehicle projection lens includes a plastic aspheric first lens, an aperture stop, a cemented lens consisting of a glass second lens and a glass third lens, and a glass fourth lens arranged in order from a magnified side to a minified side. An F-number of the vehicle projection lens is smaller than or equal to 0.8, and the vehicle projection lens consists essentially of four lenses respectively with positive, positive, negative and positive refractive powers.

Embodiments of the present disclosure generally relate to an optical system having a lens system configured to have a wide field of view and high resolution. The optical system includes three or more lens groups with ability to combat optical aberrations and produce a pupil outside of the lens group. The lens system as an image projection system projects a pattern or image rendered on a flat reticle or display of finite distance to the infinity. In an imaging system, the lens system collects light from infinity and forms an image of that object on a sensor.

Embodiments of the present disclosure generally relate to an optical system having a lens system configured to have a wide field of view and high resolution. The optical system includes three or more lens groups with ability to combat optical aberrations and produce a pupil outside of the lens group. The lens system as an image projection system projects a pattern or image rendered on a flat reticle or display of finite distance to the infinity. In an imaging system, the lens system collects light from infinity and forms an image of that object on a sensor.

A focusing mechanism, including a positioning seat, a focus ring, a lens, and a knob is provided. The lens has an optical axis. The positioning seat has a first surface, a second surface opposite to the first surface, and a sliding groove penetrating the first surface and the second surface. The focus ring is slidably and rotatably disposed on the second surface of the positioning seat. The lens is fixed to the focus ring. The focus ring has a positioning hole and is located between the positioning seat and the lens. The positioning hole is aligned to the sliding groove in a direction perpendicular to the optical axis. The knob passes through the sliding groove and is inserted into the positioning hole. The knob is pressed against the first surface of the positioning seat. A projection device is also provided.

A focusing mechanism, including a positioning seat, a focus ring, a lens, and a knob is provided. The lens has an optical axis. The positioning seat has a first surface, a second surface opposite to the first surface, and a sliding groove penetrating the first surface and the second surface. The focus ring is slidably and rotatably disposed on the second surface of the positioning seat. The lens is fixed to the focus ring. The focus ring has a positioning hole and is located between the positioning seat and the lens. The positioning hole is aligned to the sliding groove in a direction perpendicular to the optical axis. The knob passes through the sliding groove and is inserted into the positioning hole. The knob is pressed against the first surface of the positioning seat. A projection device is also provided.

A projection lens system projects an image of a reduction side into a magnification side in an image projection device, a back glass being disposed on the reduction side. In the projection lens system, all of one or more negative lenses that satisfy, in a surface on the reduction side or a surface on the magnification side, condition |h/H|<2.0 defined by height h of a most off-axis principal ray and height H of an axial ray passing through a highest pupil position satisfy conditions Tn≥98.5% and Dn/Db≤0.05 defined by transmittance Tn, thickness Dn of the negative lens on an optical axis, and total thickness Db of the back glass.

A projection lens system projects an image of a reduction side into a magnification side in an image projection device, a back glass being disposed on the reduction side. In the projection lens system, all of one or more negative lenses that satisfy, in a surface on the reduction side or a surface on the magnification side, condition |h/H|<2.0 defined by height h of a most off-axis principal ray and height H of an axial ray passing through a highest pupil position satisfy conditions Tn≥98.5% and Dn/Db≤0.05 defined by transmittance Tn, thickness Dn of the negative lens on an optical axis, and total thickness Db of the back glass.

An imaging apparatus includes an imaging optical system that has a light transmission characteristic of transmitting near-infrared light in a near-infrared light wavelength range including 1550 nm, and an imaging sensor that outputs an imaging signal by imaging the near-infrared light transmitted through the imaging optical system, the imaging sensor has sensitivity to heat radiation from a subject, and the imaging signal includes information regarding a heat radiation image by the heat radiation.

A wavefront sensor includes a splitting element configured to split an incident light beam into a plurality of light beams, an image sensor configured to receive the plurality of light beams, and a processing unit configured to calculate a wavefront of the incident light beam based on an intensity distribution of the plurality of light beams received by the image sensor. The splitting element is either in direct contact with the image sensor or in contact with the image sensor via a plate glass. In the calculation of the wavefront, the processing unit corrects a relative positional deviation between the splitting element and the image sensor by calculating a rotation about a rotation axis.