A head-mounted display (HMD) comprising a first side for facing a user of the HMD, a second side opposite to the first side, and a reflective layer for at least partially reflecting incident light incident on the second side. At least one processor of the HMD is configured to obtain luminance data indicative of a luminance of the incident light and control a display device, based on the luminance data, to control a luminance of a portion of emitted light directed towards the user of the HMD during the display of the image. Further examples relate to an HMD with a display device configured to emit light of at least one predetermined wavelength range during display of an image by the display device, and a layer arranged to at least partially prevent transmission of the light of the at least one predetermined wavelength range outward from the HMD.

A radiation source apparatus includes a vessel, a laser source, a collector, and a reflective mirror. The vessel has an exit aperture. The laser source is at one end of the vessel and configured to excite a target material to form a plasma. The collector is disposed in the vessel and configured to collect a radiation emitted by the plasma and to direct the collected radiation to the exit aperture of the vessel. The reflective mirror is in the vessel and configured to reflect the laser beam toward an edge of the vessel.

Disclosed herein is system and method for protective diamond coatings. The method may include the steps of cleaning and seeding a substrate, depositing a crystalline diamond layer on the substrate, etching the substrate; and attaching the substrate to protected matter. The crystalline diamond layer may reflect at least 28 percent of electromagnetic energy in a beam having a bandwidth of 800 nanometer to 1 micrometer.

A device includes a light source configured to generate an image light. The device also includes a lens assembly coupled with the light source. The lens assembly includes a mirror configured to transmit a first portion of the image light and reflect a second portion of the image light. The lens assembly also includes a reflective polarizer including a birefringent medium with a chirality and configured to substantially reflect the first portion of the image light output from the mirror as a polarized light having a predetermined handedness toward the mirror. The lens assembly further includes a lens disposed between the mirror and the reflective polarizer and configured to provide an optical power to the image light.

A device includes a light source configured to generate an image light. The device also includes a lens assembly coupled with the light source. The lens assembly includes a mirror configured to transmit a first portion of the image light and reflect a second portion of the image light. The lens assembly also includes a reflective polarizer including a birefringent medium with a chirality and configured to substantially reflect the first portion of the image light output from the mirror as a polarized light having a predetermined handedness toward the mirror. The lens assembly further includes a lens disposed between the mirror and the reflective polarizer and configured to provide an optical power to the image light.

An imaging device of an embodiment comprises an aperture that transmits imaging light applied to a sample, a detector including a linear sensor comprising a linear light receiving surface extending in a first direction, a first image forming element that collects components of the imaging light in the first direction and forms an image on the light receiving surface with a first wave front aberration amount, and a second image forming element that collects components of the imaging light in a second direction orthogonal to the first direction and forms an image on the light receiving surface with a second wave front aberration amount smaller than the first wave front aberration amount.

An imaging device of an embodiment comprises an aperture that transmits imaging light applied to a sample, a detector including a linear sensor comprising a linear light receiving surface extending in a first direction, a first image forming element that collects components of the imaging light in the first direction and forms an image on the light receiving surface with a first wave front aberration amount, and a second image forming element that collects components of the imaging light in a second direction orthogonal to the first direction and forms an image on the light receiving surface with a second wave front aberration amount smaller than the first wave front aberration amount.

A light emitting device includes a light emitting element and a light reflecting member that reflects light emitted from the light emitting element. The light reflecting member comprises plate-shaped light reflective particles, silica, and an alkali metal. An average particle size of the light reflective particles is 0.6 μm to 43 μm, and an average aspect ratio of the light reflective particles is 10 or higher.

A light emitting device includes a light emitting element and a light reflecting member that reflects light emitted from the light emitting element. The light reflecting member comprises plate-shaped light reflective particles, silica, and an alkali metal. An average particle size of the light reflective particles is 0.6 μm to 43 μm, and an average aspect ratio of the light reflective particles is 10 or higher.

An optical device is formed by hot stamping a demetallized hologram to an optically variable foil or to a coating of optically variable ink. In another embodiment a hologram is hot stamped to a banknote or document printed with a color-shifting ink.