Provided is an optical element in which the amount of light having a wavelength causing a disturbance noise can be reduced and light can be diffracted with a high diffraction efficiency. The optical element comprising: an optically-anisotropic layer that is formed using a composition including a liquid crystal compound and a dichroic colorant, 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.

Provided is an optical element in which the amount of light having a wavelength causing a disturbance noise can be reduced and light can be diffracted with a high diffraction efficiency. The optical element comprising: an optically-anisotropic layer that is formed using a composition including a liquid crystal compound and a dichroic colorant, 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.

An optical filter (1a) includes a light-absorbing layer (10). The light-absorbing layer absorbs light in at least a portion of the near-infrared region. When light with a wavelength of 300 nm to 1200 nm is incident on the optical filter (1a) at incident angles of 0, 30, and 40, the optical filter (1a) satisfies given transmittance requirements. IE.sub.1/2.sup.1 to 2, IAE.sub.1/2.sup.1 to 2, and ISE.sub.1/2.sup.1 to 2 defined by the following equations (1) to (3) for two incident angles 1 and 2 (1<2) selected from 0, 30, and 40 satisfy given requirements in a given domain of a wavelength .

An optical filter (1a) includes a light-absorbing layer (10). The light-absorbing layer absorbs light in at least a portion of the near-infrared region. When light with a wavelength of 300 nm to 1200 nm is incident on the optical filter (1a) at incident angles of 0, 30, and 40, the optical filter (1a) satisfies given transmittance requirements. IE.sub.1/2.sup.1 to 2, IAE.sub.1/2.sup.1 to 2, and ISE.sub.1/2.sup.1 to 2 defined by the following equations (1) to (3) for two incident angles 1 and 2 (1<2) selected from 0, 30, and 40 satisfy given requirements in a given domain of a wavelength .

In a display method or device according to one embodiment of the present invention, at least two of a photonic crystal reflection mode, a unique color reflection mode and a transmittance tuning mode may be implemented to be switched to each other within the same unit pixel. In addition, a machine readable storage medium recording a computer program performing the display method is provided.

An electromagnetic filtering system comprising an electromagnetic radiation source, a filter chamber to filter the radiation and a filter chamber control system to selectively modify the contents of the filter chamber in order to modify the wavelengths of the radiation that pass through the filter chamber. There is also provided a method of controlling an electromagnetic filtering system that comprises a controllable filter chamber capable of being controlled so as to selectively be filled with a filter material, the method comprising determining filtering characteristics to be provided by the filtering system, determining whether the filter chamber should be filled with the filter material, and controlling the filter chamber to be filled as determined.

An electromagnetic filtering system comprising an electromagnetic radiation source, a filter chamber to filter the radiation and a filter chamber control system to selectively modify the contents of the filter chamber in order to modify the wavelengths of the radiation that pass through the filter chamber. There is also provided a method of controlling an electromagnetic filtering system that comprises a controllable filter chamber capable of being controlled so as to selectively be filled with a filter material, the method comprising determining filtering characteristics to be provided by the filtering system, determining whether the filter chamber should be filled with the filter material, and controlling the filter chamber to be filled as determined.

There is provided an optical filter that can improve the stability of optical communication when used in an optical communication apparatus. The optical filter includes a polarizing plate. The optical filter is used in a transmitter of an optical communication apparatus. In one embodiment, the optical filter further includes a /4 plate, wherein an angle formed by an absorption axis of the polarizer of the polarizing plate and a slow axis of the /4 plate is from 38 to 52, and wherein the optical filter is used by being arranged so that the /4 plate is on a light-emitting element side of the transmitter.

There is provided an optical filter that can improve the stability of optical communication when used in an optical communication apparatus. The optical filter includes a polarizing plate. The optical filter is used in a transmitter of an optical communication apparatus. In one embodiment, the optical filter further includes a /4 plate, wherein an angle formed by an absorption axis of the polarizer of the polarizing plate and a slow axis of the /4 plate is from 38 to 52, and wherein the optical filter is used by being arranged so that the /4 plate is on a light-emitting element side of the transmitter.

Provided are a light filter and a spectrometer including the light filter. The light filter includes at least one filter, wherein the at least one filter includes a liquid spectrum modulation layer having different transmittance spectra according to different positions on the at least one filter. The liquid spectrum modulation layer has different thicknesses according to the different positions on the at least one filter.