Abstract: An imaging lens including a first lens group, a second lens group, and an aperture stop disposed between the first lens group and the second lens group is provided. The first lens group includes at least one and at most three lenses with refractive powers, and the second lens group has a positive refractive power and includes at least two and at most three lenses with a refractive powers. The imaging lens satisfies conditions of 2 mm<LT<20 mm and 0.8<D1/LT<1.4, where D1 is a lens diameter of the lens closest to the object side, and LT is distance along the optical axis between two outermost lens surfaces at opposite ends of the first lens group and the second lens group.

Abstract: A scanning-type optical antenna is provided, which includes a housing, a fine-tune mirror, a light signal emitter, a light signal receiver, a scanning light receiver and a rotational mechanism. The housing includes a window. The scanning light receiver disposed on the housing receives an input sector scanning light from a target antenna to generate plural light speckles. The rotational mechanism mounts the housing and adjusts the deflection angle between the housing and the target antenna according to the light speckles. The fine-tune mirror is disposed outside the housing and corresponding to the window. The light signal emitter inside the housing transmits an output signal light to the target antenna after being reflected by the fine-tune mirror through the window. The input signal light of the target antenna is transmitted to the light signal receiver inside the housing after being reflected by the fine-tune mirror and passing through the window.

Abstract: A scanning-type optical antenna is provided, which includes a housing, a fine-tune mirror, a light signal emitter, a light signal receiver, a scanning light receiver and a rotational mechanism. The housing includes a window. The scanning light receiver disposed on the housing receives an input sector scanning light from a target antenna to generate plural light speckles. The rotational mechanism mounts the housing and adjusts the deflection angle between the housing and the target antenna according to the light speckles. The fine-tune mirror is disposed outside the housing and corresponding to the window. The light signal emitter inside the housing transmits an output signal light to the target antenna after being reflected by the fine-tune mirror through the window. The input signal light of the target antenna is transmitted to the light signal receiver inside the housing after being reflected by the fine-tune mirror and passing through the window.