A metrology frame configured to receive and secure a workpiece in preparation for an interferometric determination of a spatial profile of the workpiece with the use of one or more retroreflectors removably cooperated with the frame in known pre-determined spatial relationship with respect the fiducial features of not only the workpiece but those of the metrology frame itself The metrology frame is necessarily devoid of a holographic optical element, while the measurement apparatus containing such metrology frame employs a hologram configured to generate at least one alignment optical wavefront that spatially converges on the retroreflector. The hologram is preferably structured as a set of constituent holographic regions (contained in the same, unitary or spatially-complementary housing and/or substrate) that perform different but operationally-complementary functions to facilitate the alignment of the metrology frame with respect to the converging optical wavefront with or without the workpiece in the frame. The optical measurement system employing the metrology frame and the hologram. Methods of optical alignment with use of same.

A metrology frame configured to receive and secure a workpiece in preparation for an interferometric determination of a spatial profile of the workpiece with the use of one or more retroreflectors removably cooperated with the frame in known pre-determined spatial relationship with respect the fiducial features of not only the workpiece but those of the metrology frame itself The metrology frame is necessarily devoid of a holographic optical element, while the measurement apparatus containing such metrology frame employs a hologram configured to generate at least one alignment optical wavefront that spatially converges on the retroreflector. The hologram is preferably structured as a set of constituent holographic regions (contained in the same, unitary or spatially-complementary housing and/or substrate) that perform different but operationally-complementary functions to facilitate the alignment of the metrology frame with respect to the converging optical wavefront with or without the workpiece in the frame. The optical measurement system employing the metrology frame and the hologram. Methods of optical alignment with use of same.

A system for use in imaging in the air, including: an image source, a transflective mirror and a retroreflective element. Light emitted by the image source is irradiated onto the retroreflective element after being reflected by the transflective mirror, the light is reflected on the retroreflective element and emerges in an opposite direction along an original incident path, and after being transmitted by the transflective mirror, then forms a real image. A selective transmissive film is provided on a side of the transflective mirror facing the image source, and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that first linearly polarized light incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element.

A system for use in imaging in the air, including: an image source, a transflective mirror and a retroreflective element. Light emitted by the image source is irradiated onto the retroreflective element after being reflected by the transflective mirror, the light is reflected on the retroreflective element and emerges in an opposite direction along an original incident path, and after being transmitted by the transflective mirror, then forms a real image. A selective transmissive film is provided on a side of the transflective mirror facing the image source, and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that first linearly polarized light incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element.

Disclosed are methods of forming substrates which exhibit an interference pattern (e.g., structural color) upon reflection of incident electromagnetic radiation. Provided herein are methods for creating iridescent structural color with large angular spectral separation. The effect can be generated at interfaces with dimensions that are orders of magnitude larger than the wavelength of visible light. The structural color results from light interacting with the geometrical structure of an interface (e.g., a hemispheric/dome-shaped interface between two materials having different refractive indices) in a way that causes light interference. The structural color observed when viewing the surface depends upon the angle of the viewer as well as the angle of the light incident to the surface.

Disclosed are methods of forming substrates which exhibit an interference pattern (e.g., structural color) upon reflection of incident electromagnetic radiation. Provided herein are methods for creating iridescent structural color with large angular spectral separation. The effect can be generated at interfaces with dimensions that are orders of magnitude larger than the wavelength of visible light. The structural color results from light interacting with the geometrical structure of an interface (e.g., a hemispheric/dome-shaped interface between two materials having different refractive indices) in a way that causes light interference. The structural color observed when viewing the surface depends upon the angle of the viewer as well as the angle of the light incident to the surface.

A display apparatus includes a screen formed in an arcuate shape centering on a center axis and a projection device configured to project, along projecting directions orthogonal to the center axis and different from one another, images corresponding to the projecting directions on the inner circumferential surface or the outer circumferential surface of the screen. The screen includes a retroreflective layer having a reflection surface directed to the projection device and a diffusion layer arranged on the projection device side with respect to the retroreflective layer and configured to diffuse, when transmitting light made incident from the retroreflective layer, the light wider in a first direction along the center axis than in a second direction, which is a circumferential direction centering on the center axis.

A display apparatus includes a screen formed in an arcuate shape centering on a center axis and a projection device configured to project, along projecting directions orthogonal to the center axis and different from one another, images corresponding to the projecting directions on the inner circumferential surface or the outer circumferential surface of the screen. The screen includes a retroreflective layer having a reflection surface directed to the projection device and a diffusion layer arranged on the projection device side with respect to the retroreflective layer and configured to diffuse, when transmitting light made incident from the retroreflective layer, the light wider in a first direction along the center axis than in a second direction, which is a circumferential direction centering on the center axis.

The invention provides a reflector (2) comprising a reflector wall (20), the reflector wall (20) comprising a first wall surface (22) and a second wall surface (23) defining said reflector wall (20), the reflector wall (20) comprising a light transmissive material (21), wherein the reflector wall (20) has a first dimension (d1) and a second dimension (d2) defining a first reflector wall area, wherein each wall surface (22,23) comprises a plurality of parallel arranged elongated corrugations (210), wherein the corrugations have corrugation heights (h2) relative to recesses (220) between adjacent corrugations (210) and corrugation widths (w2) defined by the distance between adjacent recesses (220) at the respective wall surfaces (22,23), wherein the corrugations (210) have curved corrugation surfaces (230) between said adjacent recesses (220) having corrugation radii (r2) at the respective wall surfaces (22,23), and wherein over at least part of one of the first dimension (d1) and the second dimension (d2) one or more of (i) the corrugation heights (h2), (ii) the corrugation widths (w2), (iii) the corrugation radii (r2), and (iv) a shortest top-top distance (w12) of corrugations tops (211) configured at different wall surfaces (22,23) vary over said wall dimension (d1,d2) for at least one of the wall surfaces (22,23). The reflector (2) has a first end (3) and a second end (4), wherein a third distance (d3) between the first end (3) and the second end (4) is bridged by one or more reflector walls (20), wherein the one or more reflector walls (20) are configured tapering from the second end (4) to the first end (3), and wherein the reflector (2) has a reflector cavity (5).

The invention provides a reflector (2) comprising a reflector wall (20), the reflector wall (20) comprising a first wall surface (22) and a second wall surface (23) defining said reflector wall (20), the reflector wall (20) comprising a light transmissive material (21), wherein the reflector wall (20) has a first dimension (d1) and a second dimension (d2) defining a first reflector wall area, wherein each wall surface (22,23) comprises a plurality of parallel arranged elongated corrugations (210), wherein the corrugations have corrugation heights (h2) relative to recesses (220) between adjacent corrugations (210) and corrugation widths (w2) defined by the distance between adjacent recesses (220) at the respective wall surfaces (22,23), wherein the corrugations (210) have curved corrugation surfaces (230) between said adjacent recesses (220) having corrugation radii (r2) at the respective wall surfaces (22,23), and wherein over at least part of one of the first dimension (d1) and the second dimension (d2) one or more of (i) the corrugation heights (h2), (ii) the corrugation widths (w2), (iii) the corrugation radii (r2), and (iv) a shortest top-top distance (w12) of corrugations tops (211) configured at different wall surfaces (22,23) vary over said wall dimension (d1,d2) for at least one of the wall surfaces (22,23). The reflector (2) has a first end (3) and a second end (4), wherein a third distance (d3) between the first end (3) and the second end (4) is bridged by one or more reflector walls (20), wherein the one or more reflector walls (20) are configured tapering from the second end (4) to the first end (3), and wherein the reflector (2) has a reflector cavity (5).