Alignment films include a copolymer of a specific vertical alignment monomer and at least one of a specific anthracene-based monomer and a specific benzyl-based monomer.

A near-to-eye display device, includes: a display screen configured to display different images in a first time division mode, a polarization converter at a light-emitting side of the display screen and configured to convert emitted light of the different images displayed by the display screen into first circularly polarized light rays and second circularly polarized light rays in a second time division mode. Here the first circularly polarized light rays and the second circularly polarized light rays are opposite in rotation direction. The device further includes a polarization lens at a side facing away from the display screen of the polarization converter, and a focusing lens at a side facing away from the display screen of the polarization converter. The polarization lens and the focusing lens are configured to focus the first circularly polarized light rays and the second circularly polarized light rays at positions of different focal lengths.

An optical element includes a light guide plate, an incidence portion, and an emission portion, in which each of the incidence portion and the emission portion includes diffraction portions, the diffraction portion includes diffraction elements, the diffraction element includes a liquid crystal diffraction layer in which a direction of an optical axis of a liquid crystal compound changes while continuously rotating in one in-plane direction, and in a case where the direction in which the direction of the optical axis changes is set as an in-plane rotation direction and a length over which the optical axis rotates by 180° is set as an in-plane period, in-plane rotation directions of liquid crystal diffraction layers of incidence diffraction elements in at least two of a plurality of the incidence diffraction portions are different from each other.

Provided are an optical film, a circularly polarizing plate, and an image display apparatus in each of which the occurrence of cracks is suppressed in the obtained film in a case of being punched. The optical film includes a stretched resin film and a liquid crystal layer formed by fixing a liquid crystal compound twist-aligned along a helical axis extending along a direction in thickness, in which a δa value calculated using a three-dimensional solubility parameter of a resin in the stretched resin film is 8.0 MPa.sup.1/2 or less, the liquid crystal layer contains a cured substance of a polyfunctional compound having two or more polymerizable groups in one molecule, and an absolute value of a difference between the δa value calculated using the three-dimensional solubility parameter of the polyfunctional compound and the δa value calculated using the three-dimensional solubility parameter of the resin is 4.0 MPa.sup.1/2 or less.

An optical element includes a linear polarizer layer and a transparent optical layer. The linear polarizer layer includes surfaces waviness and the transparent optical layer smooths the surfaces waves of the linear polarizer layer.

A phase difference film and a circularly polarizing film each achieve suppressed coloration when viewed from the front direction, a smaller difference in tint between views from the front direction and the oblique direction, and suppressed image unevenness, where the film is applied to an image display panel, in particular, an organic EL panel; as well as an image display device including the circularly polarizing film. The phase difference film includes optically anisotropic layers A and B, in which a retardation RthA of layer A in the thickness direction at a wavelength of 550 nm is larger than 0, layer A exhibits predetermined optical properties, a retardation RthB of layer B in the thickness direction at a wavelength of 550 nm is smaller than 0, layer B satisfies predetermined optical properties, and the angle formed between a slow axis of the optically anisotropic layers A and B is 90°±10°.

A head-mounted apparatus include an eyepiece that include a variable dimming assembly and a frame mounting the eyepiece so that a user side of the eyepiece faces a towards a user and a world side of the eyepiece opposite the first side faces away from the user. The dynamic dimming assembly selectively modulates an intensity of light transmitted parallel to an optical axis from the world side to the user side during operation. The dynamic dimming assembly includes a variable birefringence cell having multiple pixels each having an independently variable birefringence, a first linear polarizer arranged on the user side of the variable birefringence cell, the first linear polarizer being configured to transmit light propagating parallel to the optical axis linearly polarized along a pass axis of the first linear polarizer orthogonal to the optical axis, a quarter wave plate arranged between the variable birefringence cell and the first linear polarizer, a fast axis of the quarter wave plate being arranged relative to the pass axis of the first linear polarizer to transform linearly polarized light transmitted by the first linear polarizer into circularly polarized light, and a second linear polarizer on the world side of the variable birefringence cell.

Provided are a liquid crystal diffraction element having a high diffraction efficiency irrespective of diffraction angles, an optical element including the liquid crystal diffraction element, and an image display unit, a head-mounted display, a beam steering, and a sensor including the liquid crystal diffraction element or the optical element. The liquid crystal diffraction element includes: an optically-anisotropic layer that is formed of a liquid crystal composition including a liquid crystal compound, in which the optically-anisotropic layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, in a case where a length over which the direction of the optical axis derived from the liquid crystal compound rotates by 180° in a plane is set as a single period, a length of the single period in the liquid crystal alignment pattern gradually changes in the one in-plane direction, in a cross-sectional image of the optically-anisotropic layer obtained by observing a cross-section taken in a thickness direction parallel to the one in-plane direction with a scanning electron microscope, the optically-anisotropic layer has bright portions and dark portions extending from one surface to another surface and each of the dark portions has two or more inflection points of angle, the optically-anisotropic layer has regions where tilt directions of the dark portions are different from each other in the thickness direction, and an average tilt angle of the dark portion gradually changes in the one in-plane direction.

An object of the present invention is to provide a polarizing element which has an excellent antireflection function in a case of being applied to an image display device; and a circularly polarizing plate and an image display device, each of which has the polarizing element. The polarizing element of an embodiment of the present invention is a polarizing element having an alignment film and an anisotropic light-absorbing film formed using a dichroic substance, in which the alignment film is a photoalignment film formed using a composition for forming a photoalignment film, including a photoactive compound having a polymerizable group and a photoreactive group, a degree S of alignment of the anisotropic light-absorbing film is 0.92 or more, and an average refractive index nave at a wavelength of 400 to 700 nm of the alignment film is 1.55 to 2.0.

Polarization-based optical angle-filters disclosed herein can be engineered to transmit a prescribed amount of light as a function of incidence angle and azimuth. Such filters can transmit light without introducing artifacts, making them suitable for the image-path of an optical system. One example may include an angle-filter having an input circular polarizer, an analyzing circular polarizer, and a retarder positioned between the circular polarizers, the retarder having a thickness-direction retardation. The thickness-direction retardation of the retarder (R.sub.th) is selected to produce a prescribed angle-of-incidence dependent transmission function, and the circular polarizers reduce the amount of azimuth-dependence in the transmission function.