An optical system providing reduced retroreflection includes an optical element with an optic aperture. A retroreflection defeat filter has a partially obstructing material configured to absorb or reflect a subset of the optical system waveband while transmitting the rest. The partially obstructing material is arranged to occupy a first portion of the optic aperture being at least half of the optic aperture, and the partially obstructing material does not occupy a second portion of the optic aperture for the remainder of the optic aperture.

An optical element including a glass body is provided. The optical element includes a colored layer provided inside the glass body and positioned outside an effective aperture of the optical element. Coloring of the colored layer is a reduction pigment occurring in a glass component of the glass body. The colored layer suppresses occurrence of stray light and obtains sufficient light-shielding properties, so that a superior image quality can be achieved.

A helmet for a space suit includes a transparent section located at a front of the helmet. The transparent section includes a base glass having an inner surface located on an inside of the helmet and an outer surface located on an outside of the helmet, and a photochromatic transition glass. All or a portion, less than all, of the base glass is overlapped by the photochromatic transition glass. The helmet also includes a non-transparent section located at a back of the helmet.

A near-infrared cut filter is provided which has extremely low incident angle dependence and excellent oblique incidence characteristics. The near-infrared cut filter comprises a transparent substrate having a thickness of 0.16 to 0.26 mm and an average transmittance in a wavelength range of 800 to 1100 nm of 1% or less, and a resin layer formed at least one main surface of the transparent substrate and configured to absorb light of a specific wavelength.

A multi-element imaging lens can be formed from five plastic elements, and an optional null-power or relatively low power sixth plastic element. The lens can use selected plastic materials to reduce a thermal focal shift. In the lens, negative refractive power elements can be formed from plastic materials having a relatively large negative refractive index variation with temperature, abbreviated as dn/dT, while positive refractive power elements can be formed from plastic materials having a relatively small negative dn/dT. Reducing the thermal focal shift, as disclosed, can eliminate the need for an auto-focusing device, such as a voice coil. Reducing the thermal focal shift, as disclosed, can also eliminate the need to use one or more glass elements to further reduce thermal focal shift, which can reduce cost for the lens.

A composition including a first population of one or more plasmonic nanocrystals having a first, narrow extinction range, and one or more additional populations of one or more plasmonic nanocrystals, each of the one or more additional populations having a unique additional, narrow extinction range. An absorbance spectrum of the composition is characterized by the first, narrow extinction range and the one or more additional, narrow extinction ranges that together block infrared light wavelengths.

A substrate which is coated on one of its faces with a stack of thin layers having reflection properties in the infrared and/or in solar radiation, including two metallic functional layers, in particular based on silver. Each of the metallic functional layers is disposed between two dielectric coatings. The dielectric coating Di2 situated between the two functional layers includes at least one absorbent layer which absorbs solar radiation in the visible part of the spectrum. It has been found that for a stack for laminated glazing, some symmetry at the functional metal layers and the dielectric layers 1 and 3 is favorable.

The disclosure relates in general to illuminated panels resembling windows, and more particularly, to a system containing a light source, a diffuser and a panel combined in such a fashion as to resemble a window, skylight or curtain wall.

A multi-element imaging lens can be formed from five plastic elements, and an optional null-power or relatively low power sixth plastic element. The lens can use selected plastic materials to reduce a thermal focal shift. In the lens, negative refractive power elements can be formed from plastic materials having a relatively large negative refractive index variation with temperature, abbreviated as dn/dT, while positive refractive power elements can be formed from plastic materials having a relatively small negative dn/dT. Reducing the thermal focal shift, as disclosed, can eliminate the need for an auto-focusing device, such as a voice coil. Reducing the thermal focal shift, as disclosed, can also eliminate the need to use one or more glass elements to further reduce thermal focal shift, which can reduce cost for the lens.

A multi-element imaging lens can be formed from five plastic elements, and an optional null-power or relatively low power sixth plastic element. The lens can use selected plastic materials to reduce a thermal focal shift. In the lens, negative refractive power elements can be formed from plastic materials having a relatively large negative refractive index variation with temperature, abbreviated as dn/dT, while positive refractive power elements can be formed from plastic materials having a relatively small negative dn/dT. Reducing the thermal focal shift, as disclosed, can eliminate the need for an auto-focusing device, such as a voice coil. Reducing the thermal focal shift, as disclosed, can also eliminate the need to use one or more glass elements to further reduce thermal focal shift, which can reduce cost for the lens.