The objective optical system includes in order from an object side, a first unit having a positive refractive power, a second unit having a negative refractive power, and a third unit having a positive refractive power, and focusing is carried out by moving the second unit, the first unit and the third unit are fixed at the time of focusing, and the first unit G1 includes in order from the object side, a negative lens L1, one of a positive lens and a cemented lens, and a positive lens, and the third unit includes a positive lens, and a cemented lens of a positive lens and a negative lens, and the objective optical system satisfies the following conditional expression (3)
−20<f.sub.2/f<−5  (3) where, f.sub.2 denotes a focal length of the second unit, and f denotes a focal length of the overall objective optical system in a normal observation state.

A camera module comprises an image sensor having a size greater than or equal to 1/3.06 inch and less than or equal to 1/2.78 inch and a lens module comprising at least five lenses disposed in sequence between an object side and an image side of the camera module. A ratio between a half-image height of the lens module and a total track length of the camera module is greater than or equal to 0.5 and less than or equal to 0.6. A field of view of the lens module is greater than or equal to 100 degrees. An aperture of the lens module is greater than or equal to F1.8 and less than or equal to F2.4. An equivalent focal length of the lens module is greater than or equal to 10 mm and less than or equal to 20 mm.

A miniature imaging lens for close-range imaging includes: a first lens group, an aperture, and a second lens group sequentially arranged in a direction from the object side to the image side of an optical axis; the first lens group and the second lens group have positive focal power, an object-side clear aperture of the first lens group is larger than an image-side clear aperture of the first lens group, and an object-side clear aperture of the second lens group is less than an image-side clear aperture of the second lens group, and specific process parameters are provided. A sandwich structure lens configuration composed of a first lens group, an aperture and a second lens group can obtain a high close-range imaging effect under the condition of miniaturization, and can effectively reduce aberrations of close-range imaging, especially distortion and chromatic aberration.

A miniature imaging lens for close-range imaging includes: a first lens group, an aperture, and a second lens group sequentially arranged in a direction from the object side to the image side of an optical axis; the first lens group and the second lens group have positive focal power, an object-side clear aperture of the first lens group is larger than an image-side clear aperture of the first lens group, and an object-side clear aperture of the second lens group is less than an image-side clear aperture of the second lens group, and specific process parameters are provided. A sandwich structure lens configuration composed of a first lens group, an aperture and a second lens group can obtain a high close-range imaging effect under the condition of miniaturization, and can effectively reduce aberrations of close-range imaging, especially distortion and chromatic aberration.

The present invention relates to a multichannel imaging device and more specifically to a multichannel device wherein each optical channel has at least an optical low-pass angular filter configured to block any light propagating through the optical channel along a direction of propagation having an angle which is greater than a predefined angle θ.sub.L relative to the optical axis, the low-pass angular filter comprising at least one planar interface, separating a first material having a first refractive index n.sub.1 and a second material having a second refractive index n.sub.2, the ratio of the second refractive index over the first refractive index being lower than 1, preferably lower than 0.66.

The present invention relates to a multichannel imaging device and more specifically to a multichannel device wherein each optical channel has at least an optical low-pass angular filter configured to block any light propagating through the optical channel along a direction of propagation having an angle which is greater than a predefined angle θ.sub.L relative to the optical axis, the low-pass angular filter comprising at least one planar interface, separating a first material having a first refractive index n.sub.1 and a second material having a second refractive index n.sub.2, the ratio of the second refractive index over the first refractive index being lower than 1, preferably lower than 0.66.

An optical system includes, in order from an object side toward an image side, a first lens unit having positive refractive power, and a second lens unit having negative refractive power. A distance between consecutive ones of the lens units changes when focusing is performed. The first lens unit is stationary during focusing. The second lens unit is moved toward the image side when focus is changed from an object at infinity to an object at a short distance. Lateral magnification β2 of the second lens unit when focusing on the object at infinity, focal length f1 of the first lens unit, and focal length f2 of the second lens unit are set appropriately to satisfy predetermined mathematical conditions.

An optical system includes, in order from an object side toward an image side, a first lens unit having positive refractive power, and a second lens unit having negative refractive power. A distance between consecutive ones of the lens units changes when focusing is performed. The first lens unit is stationary during focusing. The second lens unit is moved toward the image side when focus is changed from an object at infinity to an object at a short distance. Lateral magnification β2 of the second lens unit when focusing on the object at infinity, focal length f1 of the first lens unit, and focal length f2 of the second lens unit are set appropriately to satisfy predetermined mathematical conditions.

An eye-tracking apparatus includes a first lens group, a light splitting device, a display, an image sensor, a second lens group, and a plurality of light sources. The light splitting device receives a first beam, generates a second beam, and transmits the second beam to a second surface of the first lens group. The display projects a reference mark to a target area through the light splitting device and the first lens group. The image sensor captures a detection image on the target area through the first lens group, the light splitting device, and the second lens group. The second lens group is disposed between the light splitting device and the image sensor. The light sources are disposed around the image sensor and project a plurality of beams to the target area through the first lens group, the light splitting device, and the second lens group.

An eye-tracking apparatus includes a first lens group, a light splitting device, a display, an image sensor, a second lens group, and a plurality of light sources. The light splitting device receives a first beam, generates a second beam, and transmits the second beam to a second surface of the first lens group. The display projects a reference mark to a target area through the light splitting device and the first lens group. The image sensor captures a detection image on the target area through the first lens group, the light splitting device, and the second lens group. The second lens group is disposed between the light splitting device and the image sensor. The light sources are disposed around the image sensor and project a plurality of beams to the target area through the first lens group, the light splitting device, and the second lens group.