The effective focal length of an optical system can be electronically controlled using switchable wave plates in conjunction with polarized light.

A zoom optical system according to an embodiment of the present invention comprises a first lens group, a second lens group and a third lens group sequentially aligned from an object toward an image, wherein the second lens group and third lens group can move, and an effective focal length (EFL) at a wide angle is defined by the mathematical formula below.

[00001]$2.9<\frac{EF{L}_{\mathrm{wide}}}{H_{\mathrm{imageD}}}<3.5$

Here, EFL.sub.wide means an effective focal length of the zoom optical system at a wide angle, and H.sub.imageD means a half of the diagonal length of an image sensor pixel area.

A simplified zoom lens module includes first to third lens units, first and second driving assemblies, and a housing. The lens units are arranged along an optical axis. The first driving assembly moves the second lens unit back and forth relative to the first lens unit, the second driving assembly moves the third lens unit back and forth relative to the second lens unit. The first driving assembly includes a first magnet which interacts with a second magnet, one being a permanent magnet, the other being an electromagnet. The first magnet is fixed inside the housing, the second magnet is fixed on the second lens unit. The first and second magnets are attracted to or repelled from each other by voltage and current fed to the electromagnet, thereby moving the lens and changing the focus of the lens module. A module and image-capturing device are also disclosed.

A lens barrel includes: a first lens; a first tube that holds the first lens and moves along an optical axis; a focusing lens; an actuator that drives the focusing lens; and a second tube that holds the focusing lens and the actuator and moves along the optical axis.

An imaging lens consists of, in order from the object side, a first lens group, a stop, a positive second lens group, and a third lens group. During focusing, at least the second lens group moves and the third lens group does not move. The second lens group includes at least two negative lenses. The third lens group consists of one negative lens and one positive lens.

This disclosure describes an afocal attachment that allows for alteration of received electromagnetic radiation (or “light”) prior to entry into the telescope. For example, a rifle scope may have a base magnification of 2x, and the afocal attachment may allow magnification of a received image at levels ranging from 2x to 4x. In this example, the entire telescope system with the afocal attachment installed will have an overall magnification of 4x to 8x. In another example, the magnification of the telescope can be increased, transforming a telescope with a 4x magnification into a telescope with a higher effective magnification. In some instances the afocal attachment's optical axis can be configured to permit independent adjustment, allowing for easy removal and reinstallation of the afocal attachment without a need to re-adjust the telescope itself.

An image displaying device includes a planar display panel and a light penetrating unit. The planar display panel displays a plane image. The planar display panel at least includes a first pixel group, a second pixel group and a third pixel group. The second pixel group is located between the first pixel group and the third pixel group. When vision passes through the light penetrating unit toward the planar display panel, the vision acquires a second distance of a second imaging position within the plane image relevant to the second pixel group relative to the planar display panel being greater than a first distance of a first imaging position within the plane image relevant to the first pixel group relative to the planar display panel and a third distance of a third imaging position within the plane image relevant to the third pixel group relative to the planar display panel.

An optical system for a microscope for imaging an object includes: a telescope system having an optical correction unit, which is adjustable in order to correct a spherical imaging aberration, and having a zoom optical unit, which is adjustable in order to adapt a magnification of the telescope system to a ratio of two refractive indices, one of which is assigned to an object side and an other of which is assigned to an image side, within a predetermined magnification range. The telescope system is telecentric over an entire magnification range both with respect to the object side and with respect to the image side by the zoom optical unit contained in the telescope system.

The zoom optical system according to one embodiment of the present invention comprises a first lens group, a second lens group, and a third lens group which are serially arranged from the object-side towards the image-side, wherein the first lens group comprises a plurality of fixed lenses, the second lens group comprises two movable lenses, the third lens group comprises two movable lenses, magnification is adjusted according to the movement of the second lens group, focus is adjusted according to the movement of the third lens group, the focal length at maximum magnification is at least 13 mm, and the f-number at maximum magnification is at most 3.7.

This disclosure describes an afocal attachment that allows for alteration of received electromagnetic radiation (or “light”) prior to entry into the telescope. For example, a rifle scope may have a base magnification of 2×, and the afocal attachment may allow magnification of a received image at levels ranging from 2× to 4×. In this example, the entire telescope system with the afocal attachment installed will have an overall magnification of 4× to 8×. In another example, the magnification of the telescope can be increased, transforming a telescope with a 4× magnification into a telescope with a higher effective magnification. In some instances the afocal attachment's optical axis can be configured to permit independent adjustment, allowing for easy removal and reinstallation of the afocal attachment without a need to re-adjust the telescope itself.