This optical filter 10 has an L* of at least 20 as measured by the SCE method, wherein the linear transmittance is at least 60% with respect to light the wavelength of which falls at least partially within the wavelength range of 760 nm-2,000 nm, and the temperature, at which the optical filter contracts by being heated, is at least 85° C.

Disclosed is an optical filter with L* measured by the SCE method being 20 or greater, wherein: the linear transmittance with respect to light with wavelengths being at least a portion of a wavelength range from 760 nm to 2000 nm is 60% or greater; and, before and after a light resistance test wherein light of a xenon arc lamp (average integrated illuminance of light with wavelengths from 300 nm to 400 nm:120 W/m.sup.2) is shone for 300 hours, the absolute value of a change in C* measured by the SCE method using a spectroscopic colorimeter is 6 or less.

A whiteboard film (100) according to an embodiment of the present invention includes: a diffuse reflection layer (40) to diffuse-reflect visible light; an absorptive polarizing layer (20) having a first transmission axis that is parallel to a first direction; and a reflective polarizing layer (10) being disposed between the diffuse reflection layer (40) and the absorptive polarizing layer (20) and having a second transmission axis that is substantially parallel to the first direction. A whiteboard (100a) according to an embodiment of the present invention includes: a diffuse reflection plate (40a) to diffuse-reflect visible light; an absorptive polarizing layer (20) having a first transmission axis that is parallel to a first direction; and a reflective polarizing layer (10) being disposed between the diffuse reflection plate (40a) and the absorptive polarizing layer (20) and having a second transmission axis that is substantially parallel to the first direction.

A high-precision marker, which is easy to manufacture, has a base material layer, a first layer which is laminated onto one surface of the base material layer, and which is observed in a first color, and a second layer which is partially laminated onto the first layer, is observed in a second color different from the first color, and partially conceals the first layer, wherein the first layer is observable in a region in which the second layer is not laminated, and the second layer is formed by a resist material.

A laser projection apparatus includes a laser source, a light modulating engine and a projection lens. The laser source includes a laser device, a combining component, a first lens and a phosphor wheel. The combining component includes a reflecting region and two transmitting regions. The reflecting region is configured to reflect a laser beam and a fluorescent beam incident on the reflecting region. The two transmitting regions are disposed on two sides of the reflecting region respectively, and the transmitting regions are configured to transmit a plurality of laser beams emitted by the laser device. The phosphor wheel includes a first region and a second region. The first region is configured to diffuse and reflect the laser beams incident on the first region. The second region is configured to be excited to emit a fluorescent beam due to irradiation of the laser beams incident on the second region.

An integrating sphere (10) of the present disclosure includes a hollow member (1) and a diffusive coating (4), on the inner surface of the hollow member (1), configured to scatter and reflect light from a light source within the hollow member (1) to yield diffused light. The diffusive coating (4) is coated with a hydrophobic coating (5). The accuracy of optical measurements using the integrating sphere (10) is improved by suppressed moisture absorption of the integrating sphere (10) and suppressed fluctuations in the efficiency of the integrating sphere (10).

Provided is an image display device including an optical scanner configured to scan light emitted from a light source, a parallel light generator configured to generate the scanned light as parallel light, a prism configured to refract the parallel light, and a light direction changer including a plurality of points whereon the parallel light refracted by the prism is incident and configured to reflect or diffract the parallel light and change a traveling direction of the parallel light, wherein the prism is provided on a path of each light traveling from the optical scanner to the light direction changer to adjust an optical path difference of parallel light incident on each of the plurality of points of the light direction changer.

The present invention relates to a reactor comprising a vessel (1) for containing: • a mass to be treated, and • at least one lighting device (2a, 2b) intended to promote the treatment of said mass, characterized in that each lighting device (2a, 2b) comprises a light diffuser including at least one micro-etched plate (211) which is transparent to light radiation.

This optical filter has a back-scattering property, and the linear transmittance thereof to light of at least some wavelengths in the wavelength range of 760-2000 nm is 60% or higher. Where: the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 0° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is −60° is BRDF (0°; 20°, −60°); the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 30° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is −60° is BRDF (30°; 20°, −60°); and the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 60° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is −60° is BRDF (60°; 20°, −60°), then, for the incident light having at least some wavelengths in the wavelength range of visible light, |BRDF (0°; 20°, −60°)−BRDF (30°; 20°, −60°)|/BRDF (0°; 20°, −60°) is 1.0 or lower, and |BRDF (0°; 20°, −60°)−BRDF (60°; 20°, −-60°)|/BRDF (0°; 20°, −60°) is 1.0 or lower.

A directional backlit display device includes a light source module, a reflective narrow-angle diffuser, a backlit type display panel, an eye tracking device, and a controller. The diffuser includes a shaft and is utilized to reflect and uniformly diffuse the light to provide a uniform directional light beam. The backlit type display device panel is included on the projecting optical path of the uniform directional light beam. The uniform directional light beam illuminates an image displayed on the backlit type display device panel and projects to a projection area. The controller receives an eye position information from the eye tracking device and determines a coordinate. The controller determines a corrective projection area when the coordinate deviates from the projection area, and the drive module rotates the reflective narrow-angle diffuser around an axis of the shaft according to the corrective projection area, so the image projection area moves with the eye.