Cloaking devices constructed from reflection boundaries and half-mirrors and vehicles comprising the same

A cloaking device includes an object-side, an image-side, and a cloaked region (CR) between the object-side and the image-side. An object-side CR reflection boundary, an object-side half-mirror, and an object-side external reflection boundary are positioned on the object-side, and an image-side CR reflection boundary, an image-side half-mirror, and an image-side external reflection boundary are positioned on the image-side. The object-side half-mirror and the object-side external reflection boundary are spaced apart and generally parallel to the object-side CR reflection boundary, and the image-side half-mirror and the image-side external reflection boundary are spaced apart and generally parallel to the image-side CR reflection boundary. Light from an object located on the object-side of the cloaking device and obscured by the CR is redirected around the CR via two optical paths to form an image of the object on the image-side of the cloaking device.

TECHNICAL FIELD

The present specification generally relates to apparatuses and methods for making an object appear transparent and, more specifically, to cloaking devices for pillars of vehicles and vehicles comprising the same.

BACKGROUND

Studies on cloaking devices that appear to make a pillar of a vehicle transparent have been published. Such studies disclose the use of metamaterials or the use of video cameras in combination with a display screen to allow an occupant of a vehicle to ostensibly “see” through the vehicle pillar, thereby reducing blind spots in the vehicle. However, metamaterials and video technology use complicated material designs and equipment.

Accordingly, a need exists for alternative devices that appear to make a pillar of a vehicle transparent.

SUMMARY

In one embodiment, a cloaking device includes an object-side, an image-side, a cloaked region (CR) between the object-side and the image-side, and a reference optical axis extending from the object-side to the image-side. An object-side CR reflection boundary, an object-side half-mirror, and an object-side external reflection boundary are positioned on the object-side of the cloaking device and an image-side CR reflection boundary, an image-side half-mirror, and an image-side external reflection boundary are positioned on the image-side. The object-side half-mirror and the object-side external reflection boundary are spaced apart and generally parallel to the object-side CR reflection boundary, and the image-side half-mirror and the image-side external reflection boundary are spaced apart and generally parallel to the image-side CR reflection boundary. Light from an object located on the object-side of the cloaking device and obscured by the CR is redirected around the CR via two optical paths to form an image of the object on the image-side of the cloaking device such that the light from the object appears to pass through the CR. Particularly, light from the object on the object-side of the cloaking device is redirected around the CR via a first optical path and a second optical path that is different than the first optical path. Light on the first optical path is reflected by the object-side half-mirror and the image-side half-mirror and light on the second optical path is transmitted through the object-side half-mirror and the image-side half-mirror. In some embodiments, the object-side external reflection boundary is spaced apart from and generally parallel to the object-side half-mirror and the image-side external reflection boundary is spaced apart from and generally parallel to the image-side half-mirror. In such embodiments, the object-side half-mirror and the image-side half-mirror are positioned between the object-side external reflection boundary and the image-side external reflection boundary. Also, the first optical path is: Object —object-side CR reflection boundary—object-side external reflection boundary—object-side half-mirror—image-side half-mirror—image-side external reflection boundary—image-side CR reflection boundary—Image; and the second optical path is: Object—object-side CR reflection boundary—object-side half-mirror—image-side half-mirror—image-side CR reflection boundary—Image. In other embodiments, the object-side external reflection boundary is coplanar with the object-side half-mirror, and the image-side external reflection boundary is coplanar with the image-side half-mirror. In such embodiments, the first optical path is: Object—object-side CR reflection boundary—object-side half-mirror—object-side CR reflection boundary—object-side external reflection boundary—image-side external reflection boundary—image-side CR reflection boundary—image-side half-mirror—image-side CR reflection boundary—Image; and the second optical path is: Object—object-side half-mirror—object-side CR reflection boundary—object-side external reflection boundary—image-side external reflection boundary—image-side CR reflection boundary—image-side half-mirror—Image.

According to another embodiment, a cloaking device assembly includes an object-side, an image-side, a cloaked region (CR) between the object-side and the image-side, and a reference optical axis extending from the object-side to the image-side. First object-side and first image-side CR reflection boundaries, first object-side and first image-side external reflection boundaries, and first object-side and first image-side half-mirrors are positioned on a first side of the reference optical axis. Also, second object-side and second image-side CR reflection boundaries, second object-side and second image-side external reflection boundaries, and second object-side and second image-side half-mirrors are positioned on a second side of the reference optical axis opposite the first side. The first object-side and first image-side external reflection boundaries and the first object-side and first image-side half-mirrors are spaced apart from and generally parallel to the first object-side and first image-side CR reflection boundaries. Also, the second object-side and second image-side external reflection boundaries and the second object-side and second image-side half-mirrors are spaced apart from and generally parallel to the second object-side and second image-side CR reflection boundaries. Light from an object located on the object-side of the cloaking device and obscured by the CR is redirected around the CR via two optical paths on the first side of the reference optical axis and two optical paths on the second side of the reference optical axis to form an image of the object on the image-side of the cloaking device such that the light from the object appears to pass through the CR.

According to another embodiment, a vehicle includes an A-pillar and a cloaking device positioned on the A-pillar. The cloaking device includes an object-side, an image-side, and a cloaked region (CR) between the object-side and the image-side. The A-pillar is positioned within the cloaked region, the object-side is positioned on an exterior of the vehicle and the image-side is positioned within an interior of the vehicle. An object-side CR reflection boundary, an object-side half-mirror, and an object-side external reflection boundary are positioned on the object-side of the cloaking device and an image-side CR reflection boundary, an image-side half-mirror, and an image-side external reflection boundary are positioned on the image-side. The object-side half-mirror and the object-side external reflection boundary are spaced apart and generally parallel to the object-side CR reflection boundary, and the image-side half-mirror and the image-side external reflection boundary are spaced apart and generally parallel to the image-side CR reflection boundary. Light from an object located on the object-side of the cloaking device and obscured by the A-pillar is redirected around the A-pillar via two optical paths to form an image of the object on the image-side of the cloaking device such that the light from the object appears to pass through the A-pillar. Particularly, light from the object is redirected around the A-pillar via a first optical path is reflected by the object-side half-mirror and the image-side half-mirror, and light from the object on the object-side of the cloaking device redirected around the A-pillar via a second optical path is transmitted through the object-side half-mirror and the image-side half-mirror. In embodiments, the object-side external reflection boundary is spaced apart and generally parallel to the object-side half-mirror, the image-side external reflection boundary is spaced apart and generally parallel to the image-side half-mirror, and the object-side half-mirror and the image-side half-mirror are positioned between the object-side external reflection boundary and the image-side external reflection boundary. In other embodiments, the object-side external reflection boundary is coplanar with the object-side half-mirror, and the image-side external reflection boundary is coplanar with the image-side half-mirror.

DETAILED DESCRIPTION

According to one or more embodiments described herein, a cloaking device may generally comprise a plurality of reflection boundaries and half-mirrors positioned around a cloaked region that reflect and transmit light around a cloaked region. The cloaking devices described herein may be used to cloak vehicle articles such as a vehicle A-pillar, B-pillar, C-pillar, D-pillar, etc., and remove a “blind spot” caused by the vehicle article. A blind spot refers to a region of the vehicle where an occupant's view may be obstructed. In the alternative, or in addition to, cloaking devices described herein may be used to cloak home, office and industrial articles such as extension cords, electrical conduit, piping, etc. The utilization of the reflection boundaries and half-mirrors allows an individual to perceive an image which, if not for the cloaking device, would be obstructed by an article. For example, utilization of the reflection boundaries and half-mirrors allows a driver of a vehicle to perceive an image which, if not for the cloaking device, would be obstructed by a pillar of the vehicle. Various embodiments of cloaking devices and vehicles comprising the same will be described in further detail herein with specific reference to the appended drawings.

FIG. 1generally depicts one embodiment of a cloaking device. The cloaking device includes an object-side, an image-side, and a cloaked region (CR) between the image-side and the object-side. A CR reflection boundary, an external reflection boundary, and a half-mirror are positioned on the object-side of the cloaking device, and another CR reflection boundary, external reflection boundary, and half-mirror are positioned on the image-side of the cloaking device. As used herein, the terms “boundaries” and “boundary” refer to a planar physical surface and the term “external” refers to a boundary spaced apart from (i.e., positioned) a predetermined distance from, one of the CR reflection boundaries. Also, the term “half-mirror” refers to a planar optical filter that allows light waves of a specific polarization (e.g., p-polarized light or s-polarized light) to pass through the optical filter and reflects light waves of other polarizations (e.g., s-polarized light or p-polarized light). Light from an object located on the object-side of the cloaking device and obscured by the cloaked region is redirected around the cloaked region via two optical paths to form an image of the object on the image-side of the cloaking device such that the light from the object appears to pass through the cloaked region. As used herein, the term “two optical paths” refers to a first optical path and a second optical path that is different than the first optical path due to different reflections by and/or transmittances through a plurality of optical components. For example, one optical path may include reflection of light from the object by the CR reflection boundaries and external reflection boundaries, and transmittance of the light though the half-mirrors and another optical path may include reflection of the light from the object by the CR reflection boundaries and the half-mirrors. Accordingly, an individual will see the object located on the opposite side of the cloaked region (and thus on the opposite side of a cloaked article) giving the visual impression that the cloaked article is transparent.

Still referring toFIG. 1, embodiments of a cloaking device include a cloaking assembly10with an object-side12, an image-side14and four CR reflection boundaries110,120,130,140. The object-side12is positioned above (+Y direction) a bisecting axis15and the image-side14is positioned below (−Y direction) the bisecting axis15. That is, the bisecting axis15extends between and delineates the object-side12and the image-side14. Each of the four CR reflection boundaries110,120,130,140has a length along the X-axis, a width along the Y-axis and a height along the Z-axis shown in the figures. That is, the X-axis shown in the figures extends along a length of the four CR reflection boundaries110,120,130,140, the Y-axis shown in the figures extends along a width of the four CR reflection boundaries110,120,130,140, and the Z-axis shown in the figures extends along a height of the four CR reflection boundaries110,120,130,140.

The two CR reflection boundaries110,130may be positioned on the object-side12of the cloaking assembly10to face an object ‘O’ and may be referred to herein as object-side CR reflection boundaries110,130. Also, the object-side CR reflection boundary110is positioned on a first side (+X direction) of the reference optical axis16and may be referred to herein as a first object-side CR reflection boundary110and the object-side CR reflection boundary130is positioned on a second side (−X direction) of the reference optical axis16opposite the first side and may be referred to herein as a second object-side CR reflection boundary130. The two CR reflection boundaries120,140may be positioned on the image-side14of the cloaking assembly10to provide an image ‘I’ formed by the cloaking assembly10and may be referred to herein as image-side CR reflection boundaries120,140. The image-side CR reflection boundary120is positioned on the first side (+X direction) of the reference optical axis16and may be referred to herein as a first image-side CR reflection boundary120and the image-side CR reflection boundary140is positioned on the second side (−X direction) of the reference optical axis16opposite the first side and may be referred to herein as a second image-side CR reflection boundary140.

The CR reflection boundaries110,120,130,140each have an outward facing reflection surface112,122,132,142and an inward facing surface114,124,134,144, respectively. The term “outward” used herein refers to a surface that faces away and/or reflects light away from a cloaked region ‘CR’ bounded at least partially by the CR reflection boundaries110,120,130,140, and the term “inward” used herein refers to a surface that faces towards and/or reflects light towards the cloaked region CR. In embodiments, one or more of the inward facing surfaces114,124,134,144may be an opaque surface thereby preventing light from within the cloaked region CR from propagating through one or more of the CR reflection boundaries110,120,130,140, respectively. The outward facing reflection surfaces112,122,132,142can be made from omnidirectional photonic crystals or mirrors such that light incident on the outward facing reflection surfaces112,122,132,142is reflected there from. In the alternative, one or more of the outward facing reflection surfaces112,122,132,142may be a reflection surface of a prism, e.g., a right angle prism, that totally internally reflects light incident on the surface. As used herein, the term “reflection surface” refers to a surface that reflects all modes of light (e.g. s-polarized light and p-polarized light) incident on the reflection surface. Also, as used herein the term “reflected there from” refers to at least 60% of incident light being reflected from a surface. In some embodiments, at least 70% of incident light is reflected from the surface, while in other embodiments at least 80% of incident light is reflected from the surface. In still other embodiments, at least 90% of incident light, for example at least 95% of incident light is reflected from the surface.

The CR reflection boundaries110,120,130,140may have an apex end116,126,136,146and a side end118,128,138,148, respectively. The side ends118,128,138,148are spaced apart from the apex ends116,126,136,146, respectively, and the CR reflection boundaries110,120,130,140extend between apex ends116,126,136,146and side ends118,128,138,148, respectively. In embodiments, the apex ends116,136of the two object-side CR reflection boundaries110,130, respectively, meet or intersect at an apex190, and in the alternative or in addition to, the apex ends126,146of the two image-side CR reflection boundaries120,140, respectively, meet or intersect at an apex192. In such embodiments, the reference optical axis16bisects the apex190and the apex192, and may be a centerline between a first side (+X direction) and a second side (−X direction) of the cloaking assembly10. In other embodiments, the apex ends116,136of the two object-side CR reflection boundaries110,130, respectively, are spaced apart from each other and/or the apex ends126,146of the two image-side CR reflection boundaries120,140, respectively, are spaced apart from each other such that a uncloaked region or gap (not shown) is present between the spaced apart apex ends116,136and/or spaced apart apex ends126,146. In such embodiments, an image of the portion of the object O positioned above (+Y direction) the uncloaked region is not provided on the image-side14of the cloaking assembly10. Also, in embodiments, the side end118may be positioned adjacent to and may be joined to side end128and the side end138may be positioned adjacent to and may be joined to side end148as depicted inFIG. 1. In other embodiments, the side ends118,138may be spaced apart (Y direction) from the side ends128,148(not shown).

In embodiments, the two object-side CR reflection boundaries110,130and the two image-side CR reflection boundaries120,140form the cloaked region CR that is bound at least partly by the inward facing surfaces114,134,124,144. The two object-side CR reflection boundaries110,130and the two image-side CR reflection boundaries120,140have a height ‘h’ (FIG. 5) in the Z-direction of the coordinate axes in the figures and light reflected or transmitted within the cloaked region CR does not pass through the inward facing surfaces114,134,124,144. Accordingly, an article located within the cloaked region CR (e.g., a cloaked article) is not visible to an observer viewing the cloaking assembly10from the image-side14in the +Y direction.

Still referring toFIG. 1, the cloaking assembly10may include four external optical component assemblies150,160,170,180spaced apart and oriented generally parallel (within +/−2°) to each of the CR reflection boundaries110,120,130,140, respectively. In embodiments, the four external optical component assemblies150,160,170,180may include four half-mirrors152,162,172,182and four external reflection boundaries154,164,174,184spaced apart and oriented generally parallel to each of the CR reflection boundaries110,120,130,140, respectively. Each of the half-mirrors152,162,172,182, and each of the four external reflection boundaries154,164,174,184, has a length along the X-axis, a width along the Y-axis and a height along the Z-axis shown in the figures. As depicted inFIG. 1, the four external reflection boundaries154,164,174,184may be spaced apart and oriented generally parallel to each of the four half-mirrors152,162,172,182, respectively. The two half-mirrors152,172and the two external reflection boundaries154,174may be positioned on the object-side12of the cloaking assembly10and may be referred to herein as object-side half-mirrors152,172and object-side external reflection boundaries154,174, respectively. The object-side half-mirror152and the object-side external reflection boundary154are positioned on the first side (+X direction) of the reference optical axis16and may be referred to herein as a first object-side half-mirror152and a first object-side external reflection boundary154. The object-side half-mirror172and the object-side external reflection boundary174are positioned on the second side (−X direction) of the reference optical axis16opposite the first side and may be referred to herein as a second object-side half-mirror172and a second object-side external reflection boundary174. The two half-mirrors162,182and the two external reflection boundaries164,184may be positioned on the image-side14of the cloaking assembly10and may be referred to herein as image-side half-mirrors162,182and image-side external reflection boundaries164,184, respectively. The image-side half-mirror162and the image-side external reflection boundary164are positioned on the first side (+X direction) of the reference optical axis16and may be referred to herein as a first image-side half-mirror162and a first image-side external reflection boundary164. The image-side half-mirror182and the image-side external reflection boundary184are positioned on the second side (−X direction) of the reference optical axis16opposite the first side and may be referred to herein as a second image-side half-mirror182and a second image-side external reflection boundary184.

Each of the half-mirrors152,162,172,182includes a first end151,161,171,181, respectively, proximal to the bisecting axis15and a second end153,163,173,183, respectively, distal from the bisecting axis15. Also, the external reflection boundaries154,164,174,184include a first end155,165,175,185, respectively, proximal to the bisecting axis15and a second end157,167,177,187, respectively, distal from the bisecting axis15. The second end153of the first object-side half-mirror152and the first end155of the first object-side external reflection boundary154may be positioned on a line17extending parallel to the X-axis depicted inFIG. 1. Extending from the intersection of the line17and the first object-side CR reflection boundary110in the +Y direction is an optical path transition axis18discussed in greater detail below. Similarly, the second end173of the second object-side half-mirror172and the first end175of the second object-side external reflection boundary174may be positioned on a line17′ extending parallel to the X-axis depicted inFIG. 1. Extending from the intersection of the line17′ and the second object-side CR reflection boundary130in the +Y direction is an optical path transition axis18′ discussed in greater detail below. In embodiments, the line17and the line17′ are co-linear. In other embodiments, the line17and the line17′ are not co-linear.

The half-mirrors152,162,172,182reflect a specific mode of visible light. Specifically, each of the half-mirrors152,162,172,182may be an s-polarizer half-mirror or a p-polarizer half-mirror. The half-mirrors152,162,172,182may be in the form of a diffraction grating or thin film polarizer that reflects the s-mode of visible light and allows the p-mode of visible light to pass through (a p-polarization diffraction grating or thin film), or in the alternative, reflects the p-mode of visible light and allows the s-mode of the visible light to pass through (an s-polarization diffraction grating or thin film). The half-mirrors152,162may be both s-polarizer half-mirrors or p-polarizer half-mirrors and the half-mirrors172,182may be both s-polarizer half-mirrors or p-polarizer half-mirrors. That is, the half-mirrors152,162may be s-polarizer mirrors and the half-mirrors172,182may be p-polarizer half-mirrors; the half-mirrors152,162may be p-polarizer mirrors and the half-mirrors172,182may be s-polarizer half-mirrors; or all of the half-mirrors152,162,172,182may be s-polarizer half-mirrors or p-polarizer half-mirrors.

Each of the external reflection boundaries154,164,174,184has an inward facing reflection surface156,166,176,186and an outward facing surface158,168,178,188, respectively. The inward facing reflection surfaces156,166,176,186can be made from omnidirectional photonic crystals or mirrors such that light incident on the inward facing reflection surfaces156,166,176,186is reflected there from. In the alternative, one or more of the inward facing reflection surfaces156,166,176,186may be a surface of a prism, e.g., a right angle prism, that totally internal reflects light incident on the surface. In embodiments, one or more of the outward facing surfaces158,168,178,188may be an opaque surface that may prevent or block light from propagating through the external reflection boundaries154,164,174,184, respectively.

Still referring toFIG. 1, light from the object O on the first side (+X direction) of the reference optical axis16travels from the object-side12around the cloaked region CR and forms a portion of an image ‘I’ on the image-side14via two different optical paths. Particularly, light from the object positioned above (+Y direction) the cloaking assembly10between the reference optical axis16and the optical path transition axis18that incident on the cloaking assembly10(shown as arrow ‘1’ inFIG. 1) travels from the object-side12around the cloaked region CR and forms a portion of an image ‘I’ via a first optical path ‘A’. Light from the object positioned above (+Y direction) the cloaking assembly10between the optical path transition axis18and the second end157of the first object-side external reflection boundary154that is incident on the cloaking assembly10(shown as arrow1′ inFIG. 1) travels from the object-side12around the cloaked region CR and forms a portion of the image I via a second optical path ‘B’. Accordingly, the optical path transition axis18delineates a first portion on the first side (+X direction) of the cloaking assembly10with a first optical path (e.g., optical path A) from a second portion on the first side (+X direction) of the cloaking assembly10with a second optical path (e.g., optical path B).

Regarding the first optical path A on the first side (+X direction) of the reference optical axis16, the first object-side CR reflection boundary110is positioned relative to the first object-side external reflection boundary154such that light1from the object O is reflected by the outward facing reflection surface112of the first object-side CR reflection boundary110onto the first object-side external reflection boundary154(shown as arrow ‘2’ inFIG. 1). Light2is reflected by the inward facing reflection surface156of the first object-side external reflection boundary154. The first external reflection boundary154is positioned relative to the first object-side half-mirror152such that light2is reflected by the inward facing reflection surface156onto the first object-side half-mirror152(shown as arrow ‘3’ inFIG. 1). Light3is polarized by the first object-side half-mirror152such that one mode of light3is transmitted through the first object-side half-mirror152and another mode of light3is reflected by the first object-side half-mirror152. A non-limiting example of the first object-side half-mirror152in the form of a p-polarization half-mirror is depicted inFIG. 1. Accordingly, p-polarized light (shown as double-dashed center lines in the figures in contrast to single-dashed center lines for the bisecting axis15and the reference optical axis16) is transmitted through the first object-side half-mirror152(shown as arrow ‘4’ inFIG. 1). The first object-side half-mirror152is positioned relative to the first image-side half-mirror162such that light4propagates to and is incident on the first image-side half-mirror162. As noted above, the first image-side half-mirror162is the same type of half-mirror (polarizer) as the first object-side half-mirror152. Accordingly, the first image-side half-mirror162is a p-polarized half-mirror and light4propagates through the first image-side half-mirror162(shown as arrow ‘5’ inFIG. 1). The first image-side half-mirror162is positioned relative to the first image-side external reflection boundary164such that light5propagates to and is incident on the first image-side external reflection boundary164. Light5is reflected by the inward facing reflection surface166of the first image-side external reflection boundary164(shown as arrow ‘6’ inFIG. 1). The first image-side external reflection boundary164is positioned relative to the first image-side CR reflection boundary120such that light6propagates to and is incident on the outward facing reflection surface122of the first image-side CR reflection boundary120. Light6is reflected generally parallel to light1by the outward facing reflection surface122(shown as arrow ‘7’ inFIG. 1) and forms a portion of the image I on the image-side14of the cloaking assembly10. It should be understood that the portion of the image I formed by light that travels from the object-side12around the cloaked region CR via the first optical path A on the first side (+X direction) of the reference optical axis16corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly10between the reference optical axis16and the optical path transition axis18.

Accordingly, light from the object O may travel from the object-side12to the image-side14via the first optical path A: object O—first object-side CR reflection boundary110—first object-side external reflection boundary154—first object-side half-mirror152—first image-side half-mirror162—first image-side external reflection boundary164—first image-side CR reflection boundary120—image I. That is, light from the object O may travel from the object-side12to the image-side14via the first optical path A: object O—reflection from the outward facing reflection surface112of the first object-side CR reflection boundary110—reflection from the inward facing reflection surface156of the first object-side external reflection boundary154—transmittance through the first object-side half-mirror152—transmittance through the first image-side half-mirror162—reflection from the inward facing reflection surface166of the first image-side external reflection boundary164—reflection from the outward facing reflection surface122of the first image-side CR reflection boundary120—image I.

Regarding the second optical path B on the first side (+X direction) of the reference optical axis16, the first object-side CR reflection boundary110is positioned relative to the first object-side half-mirror152such that light1′ is reflected by the outward facing reflection surface112of the first object-side CR reflection boundary110onto the first object-side half-mirror152(shown as arrow ‘2′’ inFIG. 1). Light2′ is polarized by the first object-side half-mirror152such that one mode of light2′ is reflected by the first object-side half-mirror152and another mode of light2′ is transmitted through the first object-side half-mirror152. As noted above, a non-limiting example of the first object-side half-mirror152in the form of a p-polarization half-mirror is depicted inFIG. 1. Accordingly, s-polarized light (shown as dashed lines in the figures) is reflected by the first object-side half-mirror152(shown as arrow3′ inFIG. 1). The first object-side half-mirror152is positioned relative to the first image-side half-mirror162such that light3′ propagates to and is incident on the first image-side half-mirror162. As noted above, the first image-side half-mirror162is the same type of half-mirror (polarizer) as the first object-side half-mirror152. Accordingly, light3′ is reflected by the first image-side half-mirror162(shown as arrow ‘4′’ inFIG. 1). The first image-side half-mirror162is positioned relative to the first image-side CR reflection boundary120such that light4′ propagates to and is incident on the outward facing reflection surface122of the first image-side CR reflection boundary120. Light4′ is reflected generally parallel to light1′ by the outward facing reflection surface122as light5′ and forms a portion of the image I on the image-side14of the cloaking assembly10. It should be understood that the portion of the image I formed by light that travels from the object-side12around the cloaked region CR via the second optical path B on the first side (+X direction) of the reference optical axis16corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly10between the optical path transition axis18and the second end157of the first object-side external reflection boundary154.

Accordingly, light from the object O may travel from the object-side12to the image-side14via the second optical path B: object O—first object-side CR reflection boundary110—first object-side half-mirror152—first image-side half-mirror162—first image-side CR reflection boundary120—image I. That is, light from the object O may travel from the object-side12to the image-side14via the second optical path B: object O—reflection from the outward facing reflection surface112of the first object-side CR reflection boundary110—reflection from the first object-side half-mirror152—reflection from the first image-side half-mirror162—reflection from the outward facing reflection surface122of the first image-side CR reflection boundary120—image I.

Still referring toFIG. 1, light from the object O on the second side (−X direction) of the reference optical axis16travels from the object-side12around the cloaked region CR and forms a portion of an image ‘I’ via the two different optical paths A and B. Particularly, light from the object positioned above (+Y direction) the cloaking assembly10between the reference optical axis16and the optical path transition axis18′ that is incident on the cloaking assembly10(light1) travels from the object-side12around the cloaked region CR and forms a portion of an image ‘I’ via the first optical path A. Light from the object positioned above (+Y direction) the cloaking assembly10between the optical path transition axis18′ and the second end177of the second object-side external reflection boundary174that is incident on the cloaking assembly10(light1′) travels from the object-side12around the cloaked region CR and forms a portion of the image I via the second optical path B.

Regarding the first optical path A on the second side (−X direction) of the reference optical axis16, the second object-side CR reflection boundary130is positioned relative to the second object-side external reflection boundary174such that light1is reflected by the outward facing reflection surface132of the second object-side CR reflection boundary130onto the second object-side external reflection boundary174as light2. Light2is reflected by the inward facing reflection surface176of the second object-side external reflection boundary174. The second object-side external reflection boundary174is positioned relative to the second object-side half-mirror172such that light2is reflected by the inward facing reflection surface176onto the second object-side half-mirror172as light3. Light3is polarized by the second object-side half-mirror172such that one mode of light3is transmitted through the second object-side half-mirror172and another mode of light3is reflected by the second object-side side half-mirror172. A non-limiting example of the second object-side half-mirror172in the form of a p-polarization half-mirror is depicted inFIG. 1. Accordingly, p-polarized light is transmitted through the second object-side half-mirror172as light4. The second object-side half-mirror172is positioned relative to the second image-side half-mirror182such that light4propagates to and is incident on the second image-side half-mirror182. As noted above, the second image-side half-mirror182is the same type of half-mirror (polarizer) as the second object-side half-mirror172. Accordingly, light4propagates through the second image-side half-mirror182as light5. The second image-side half-mirror182is positioned relative to the second image-side external reflection boundary184such that light5propagates to and is incident on the second image-side external reflection boundary184. Light5is reflected by the inward facing reflection surface186of the second image-side external reflection boundary184as light6. The second image-side external reflection boundary184is positioned relative to the second image-side CR reflection boundary140such that light6propagates to and is incident on the outward facing reflection surface142of the second image-side CR reflection boundary140. Light6is reflected generally parallel to light1by the outward facing reflection surface142as light7and forms a portion of the image I on the image-side14of the cloaking assembly10. It should be understood that the portion of the image I formed by light that travels from the object-side12around the cloaked region CR via the second optical path A on the second side (−X direction) of the reference optical axis16corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly10between the reference optical axis16and the optical path transition axis18′.

Accordingly, light from the object O may travel from the object-side12to the image-side14via the first optical path A: object O—second object-side CR reflection boundary130—second object-side external reflection boundary174—second object-side half-mirror172—second image-side half-mirror182—second image-side external reflection boundary184—second image-side CR reflection boundary140—image I. That is, light from the object O may travel from the object-side12to the image-side14via the first optical path A: object O—reflection from the outward facing reflection surface132of the second object-side CR reflection boundary130—reflection from the inward facing reflection surface176of the second object-side external reflection boundary174—transmittance through the second object-side half-mirror172—transmittance through the second image-side half-mirror182—reflection from the inward facing reflection surface186of the second image-side external reflection boundary184—reflection from the outward facing reflection surface142of the second image-side CR reflection boundary140—image I.

Regarding the second optical path B on the second side (−X direction) of the reference optical axis16, the second object-side CR reflection boundary130is positioned relative to the second object-side half-mirror172such that light1′ is reflected by the outward facing reflection surface132of the second object-side CR reflection boundary130onto the second object-side half-mirror172as light2′. Light2′ is polarized by the second object-side half-mirror172such that one mode of light2′ is reflected by the second object-side half-mirror172and another mode of light2′ is transmitted through the second object-side half-mirror172. As noted above, a non-limiting example of the second object-side half-mirror172in the form of a p-polarization half-mirror is depicted inFIG. 1. Accordingly, s-polarized light is reflected by the second object-side half-mirror172as light3′. The second object-side half-mirror172is positioned relative to the second image-side half-mirror182such that light3′ propagates to and is incident on the second image-side half-mirror182. As noted above, the second image-side half-mirror182is the same type of half-mirror (polarizer) as the second object-side half-mirror172. Accordingly, light3′ is reflected by the second image-side half-mirror182as light4′. The second image-side half-mirror182is positioned relative to the second image-side CR reflection boundary140such that light4′ propagates to and is incident on the outward facing reflection surface142of the second image-side CR reflection boundary140. Light4′ is reflected generally parallel to light1′ by the outward facing reflection surface142and forms a portion of the image I on the image-side14of the cloaking assembly10. It should be understood that the portion of the image I formed by light that travels from the object-side12around the cloaked region CR via the second optical path B on the second side (−X direction) of the reference optical axis16corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly10between the optical path transition axis18′ and the second end177of the second object-side external reflection boundary174.

Accordingly, light from the object O may travel from the object-side12to the image-side14via the second optical path B: object O—the second object-side CR reflection boundary130—second object-side half-mirror172—second image-side half-mirror182—second image-side CR reflection boundary140—image I. That is, light from the object O may travel from the object-side12to the image-side14via the second optical path B: object O—reflection from the outward facing reflection surface132of the second object-side CR reflection boundary130—reflection from the second object-side half-mirror172—reflection from the second image-side half-mirror182—reflection from the outward facing reflection surface142of the second image-side CR reflection boundary140—image I.

In combination, i.e., light1on the first side (+X direction) and the second side (−X direction) of the reference optical axis16from the object O on the object-side12of the cloaking assembly10propagates to the image-side14via the first optical paths A: object O—reflection from the outward facing reflection surfaces112,132of the first and second object-side CR reflection boundaries110,130, respectively—reflection from the inward facing reflection surfaces156,176of the first and second object-side external reflection boundaries154,174, respectively—transmittance through the first and second object-side half-mirrors152,172—transmittance through the first and second image-side half-mirrors162,182—reflection from the inward facing reflection surfaces166,186of the first and second image-side external reflection boundaries164,184, respectively—reflection from the outward facing reflection surfaces122,142of the first and second image-side CR reflection boundaries120,140, respectively—image I. Also, light1′ on the first side (+X direction) and the second side (−X direction) of the reference optical axis16from the object O on the object-side12of the cloaking assembly10propagates to the image-side14via the second optical paths B: object O—reflection from the outward facing reflection surfaces112,132of the first and second object-side CR reflection boundaries110,130, respectively—reflection from the first and second object-side half-mirrors152,172—reflection from the first and second image-side half-mirrors162,182—reflection from the outward facing reflection surfaces122,142of the first and second image-side CR reflection boundaries120,140, respectively—image I.

WhileFIG. 1depicts the CR reflection boundaries110,120,130,140, half-mirrors152,162,172,182, and external reflection boundaries154,164,174,184as stand-alone components, it should be understood that the CR reflection boundaries110,120,130,140and the external optical component assemblies150,160,170,180may be provided as a single unit or a plurality of assembled units. For example, the external optical component assemblies150,160,170,180may be formed from a plurality of prisms that comprise the CR reflection boundaries110,120,130,140, the half-mirrors152,162,172,182, and the external reflection boundaries154,164,174,184. It should also be understood that the cloaking assembly10may cloak an object within the cloaked region CR including only the first object-side and image-side CR reflection boundaries110,120, the first object-side and image-side half-mirrors152,162, and the first object-side and image-side external reflection boundaries154,164. That is, an object positioned on the first side (+X direction) of the reference optical axis16within the cloaked region CR would be cloaked by the first object-side and image-side CR reflection boundaries110,120, first object-side and image-side half-mirrors152,162, and first object-side and image-side external reflection boundaries154,164. In the alternative, an object positioned on the second side (−X direction) of the reference optical axis16within the cloaked region CR would be cloaked by the second object-side and image-side CR reflection boundaries130,140, second object-side and image-side half-mirrors172,182, and second object-side and image-side external reflection boundaries174,184.

Referring nowFIG. 2, embodiments of a cloaking assembly20with external reflection boundaries and half-mirrors positioned coplanar with each other is depicted. The cloaking assembly20includes an object-side22, an image-side24, four CR reflection boundaries210,220,230,240, and a cloaked region CR is at least partially bounded by the four CR reflection boundaries210,220,230,240. The object-side22is positioned above (+Y direction) a bisecting axis25and the image-side24is positioned below (−Y direction) the bisecting axis25. That is, the bisecting axis25extends between and delineates the object-side22and the image-side24. Each of the four CR reflection boundaries210,220,230,240has a length along the X-axis, a width along the Y-axis and a height along the Z-axis shown in the figures. That is, the X-axis shown in the figures extends along a length of the four CR reflection boundaries210,220,230,240, the Y-axis shown in the figures extends along a width of the four CR reflection boundaries210,220,230,240, and the Z-axis shown in the figures extends along a height of the four CR reflection boundaries210,220,230,240.

The two CR reflection boundaries210,230may be positioned on the object-side22of the cloaking assembly20to face an object ‘O’ and may be referred to herein as object-side CR reflection boundaries210,230. Also, the object-side CR reflection boundary210is positioned on a first side (+X direction) of the reference optical axis26and may be referred to herein as a first object-side CR reflection boundary210and the object-side CR reflection boundary230is positioned on a second side (−X direction) of the reference optical axis26opposite the first side and may be referred to herein as a second object-side CR reflection boundary230. The two CR reflection boundaries220,240may be positioned on the image-side24of the cloaking assembly20to provide an image ‘I’ formed by the cloaking assembly20and may be referred to herein as image-side CR reflection boundaries220,240. The image-side CR reflection boundary220is positioned on the first side (+X direction) of the reference optical axis26and may be referred to herein as a first image-side CR reflection boundary220and the image-side side CR reflection boundary240is positioned on the second side (−X direction) of the reference optical axis26opposite the first side and may be referred to herein as a second image-side CR reflection boundary240.

The CR reflection boundaries210,220,230,240each have an outward facing reflection surface212,222,232,242and an inward facing surface214,224,234,244, respectively. In embodiments, one or more of the inward facing surfaces214,224,234,244may be an opaque surface that prevents light from within the cloaked region CR from propagating through one or more of the CR reflection boundaries210,220,230,240. The outward facing reflection surfaces212,222,232,242may be made from omnidirectional photonic crystals or mirrors such that light incident on the outward facing reflection surfaces212,222,232,242is reflected there from. In the alternative, one or more of the outward facing reflection surfaces212,222,232,242may be a surface of a prism, e.g., a right angle prism, that totally internally reflects light incident on the surface.

The CR reflection boundaries210,220,230,240may have an apex end216,226,236,246and a side end218,228,238,248, respectively. The side ends218,228,238,248are spaced apart from the apex ends216,226,236,246, respectively, and the CR reflection boundaries210,220,230,240extend between the apex ends216,226,236,246and the side ends218,228,238,248, respectively. In embodiments, the apex ends216,236of the two object-side CR reflection boundaries210,230, respectively, meet or intersect at an apex290, and in the alternative or in addition to, the apex ends226,246of the two image-side CR reflection boundaries220,240, respectively, meet or intersect at an apex292. In such embodiments, the reference optical axis26bisects the apex290and the apex292, and may be a centerline between a first side (+X direction) and a second side (−X direction) of the cloaking assembly20. In other embodiments, the apex ends216,236of the two object-side CR reflection boundaries210,230, respectively, are spaced apart from each other and/or the apex ends226,246of the two image-side CR reflection boundaries220,240, respectively, are spaced apart from each other such that a uncloaked region or gap (not shown) is present between the spaced apart apex ends216,236and/or spaced apart apex ends226,246. In such embodiments, an image of the portion of the object O positioned above (+Y direction) the uncloaked region is not provided on the image-side24of the cloaking assembly20. Also, in embodiments, the side end218may be positioned adjacent to and may be joined to side end228and the side end238may be positioned adjacent to and may be joined to side end248as depicted inFIG. 2. In other embodiments, the side ends218,238may be spaced apart (Y direction) from the side ends228,248(not shown).

In embodiments, the two object-side CR reflection boundaries210,230and the two image-side CR reflection boundaries220,240form the cloaked region CR that is bound at least partly by the inward facing surfaces214,234,224,244. The two object-side CR reflection boundaries210,230and the two image-side CR reflection boundaries220,240have a height ‘h’ (FIG. 5) in the Z-direction of the coordinate axes in the figures and light reflected or transmitted within the cloaked region CR does not pass through the inward facing surfaces214,234,224,244. Accordingly, an article located within the cloaked region CR (e.g., a cloaked article) is not visible to an observer viewing the cloaking assembly20from the image-side24in the +Y direction.

Still referring toFIG. 2, the cloaking assembly20may include four external optical component assemblies250,260,270,280spaced apart and oriented generally parallel (within +/−2°) to each of the CR reflection boundaries210,220,230,240, respectively. In embodiments, the four external optical component assemblies250,260,270,280may include four half-mirrors252,262,272,282and four external reflection boundaries254,264,274,284spaced apart and oriented generally parallel to each of the CR reflection boundaries210,220,230,240, respectively. Each of the half-mirrors252,262,272,282, and each of the four external reflection boundaries254,264,274,284, have a length along the X-axis, a width along the Y-axis and a height along the Z-axis shown in the figures. As depicted inFIG. 2, the four external reflection boundaries254,264,274,284are coplanar with each of the four half-mirrors252,262,272,282, respectively. The two half-mirrors252,272and the two external reflection boundaries254,274may be positioned on the object-side22of the cloaking assembly20and may be referred to herein as object-side half-mirrors252,272and object-side external reflection boundaries254,274, respectively. The object-side half-mirror252and the object-side external reflection boundary254are positioned on the first side (+X direction) of the reference optical axis26and may be referred to herein as a first object-side half-mirror252and a first object-side external reflection boundary254. The object-side half-mirror272and the object-side external reflection boundary274are positioned on the second side (−X direction) of the reference optical axis26opposite the first side and may be referred to herein as a second object-side half-mirror272and a second object-side external reflection boundary274. The two half-mirrors262,282and the two external reflection boundaries264,284may be positioned on the image-side24of the cloaking assembly20and may be referred to herein as image-side half-mirrors262,282and image-side external reflection boundaries264,284, respectively. The image-side half-mirror262and the image-side external reflection boundary264are positioned on the first side (+X direction) of the reference optical axis26and may be referred to herein as a first image-side half-mirror262and a first image-side external reflection boundary264. The image-side half-mirror282and the image-side external reflection boundary284are positioned on the second side (−X direction) of the reference optical axis26opposite the first side and may be referred to herein as a second image-side half-mirror282and a second image-side external reflection boundary284.

The half-mirrors252,262,272,282include a first end251,261,271,281, respectively, proximal to the bisecting axis25and a second end253,263,273,283, respectively, distal from the bisecting axis25. Also, the external reflection boundaries254,264,274,284include a first end255,265,275,285, respectively, proximal to the bisecting axis25and a second end257,267,277,287, respectively, distal from the bisecting axis25. The first end251of the first object-side half-mirror252and the second end257of the first object-side external reflection boundary254may be positioned on a line27extending parallel to the X-axis depicted inFIG. 2. Extending from the intersection of the line27and the first object-side CR reflection boundary210in the +Y direction parallel to the Y-axis depicted in the figures is an optical path transition axis28discussed in greater detail below. Similarly, the first end271of the second object-side half-mirror272and the second end277of the second object-side external reflection boundary274may be positioned on a line27′ extending parallel to the X-axis depicted inFIG. 2. Extending from the intersection of the line27′ and the second object-side CR reflection boundary230in the +Y direction parallel to the Y-axis is an optical path transition axis28′ discussed in greater detail below. In embodiments, the line27and the line27′ are co-linear. In other embodiments, the line27and the line27′ are not co-linear.

The half-mirrors252,262,272,282reflect a specific mode of visible light. Specifically, each of the half-mirrors252,262,272,282may be an s-polarizer half-mirror or a p-polarizer half-mirror. The half-mirrors252,262,272,282may be in the form of a diffraction grating or thin film polarizer that reflects the s-mode of visible light and allows the p-mode of visible light to pass through (a p-polarization diffraction grating or thin film), or in the alternative, reflects the p-mode of visible light and allows the s-mode of the visible light to pass through (an s-polarization diffraction grating or thin film). The half-mirrors252,262may both be s-polarizer half-mirrors or p-polarizer half-mirrors and the half-mirrors272,282may both be s-polarizer half-mirrors or p-polarizer half-mirrors, i.e. the half-mirrors252,262may be s-polarizer mirrors and the half-mirrors272,282may be p-polarizer half-mirrors; the half-mirrors252,262may be p-polarizer mirrors and the half-mirrors272,282may be s-polarizer half-mirrors; or all of the half-mirrors252,262,272,282may be s-polarizer half-mirrors or p-polarizer half-mirrors.

Each of the external reflection boundaries254,264,274,284has an inward facing reflection surface256,266,276,286and an outward facing surface258,268,278,288, respectively. The inward facing reflection surfaces256,266,276,286can be made from omnidirectional photonic crystals or mirrors such that light incident on the inward facing reflection surfaces256,266,276,286is reflected there from. In the alternative, one or more of the inward facing reflection surfaces256,266,276,286can be a surface of a prism, e.g., a right angle prism, that totally internally reflects light incident on the surface. In embodiments, one or more of the outward facing surfaces258,268,278,288may be an opaque surface that prevents light from propagating through the external reflection boundaries254,264,274,284, respectively.

Still referring toFIG. 2, light from the object O on the first side (+X direction) of the reference optical axis26travels from the object-side22around the cloaked region CR and forms a portion of an image ‘I’ on the image-side24via two different optical paths. Particularly, light from the object positioned above (+Y direction) the cloaking assembly20between the reference optical axis26and the optical path transition axis28that is incident on the cloaking assembly20(light1) travels from the object-side22around the cloaked region CR and forms a portion of an image ‘I’ via a first optical path ‘C’. Light from the object positioned above (+Y direction) the cloaking assembly20between the optical path transition axis28and the second end257of the first object-side external reflection boundary254that is incident on the cloaking assembly20(light1′) travels from the object-side22around the cloaked region CR and forms a portion of the image I via a second optical path ‘D’. Accordingly, the optical path transition axis28delineates a first portion on the first side (+X direction) of the cloaking assembly20with a first optical path (e.g., optical path C) from a second portion on the first side (+X direction) of the cloaking assembly20with a second optical path (e.g., optical path D).

Regarding the first optical path C on the first side (+X direction) of the reference optical axis26, the first object-side CR reflection boundary210is positioned relative to the first object-side external reflection boundary254such that light1from the object O is reflected by the outward facing reflection surface212of the first object-side CR reflection boundary210onto the first object-side half-mirror252as light2. Light2is polarized by the first object-side half-mirror252such that one mode of light2is reflected by the first object-side half-mirror252and another mode of light2is transmitted through the first object-side half-mirror252. A non-limiting example of the first object-side half-mirror252in the form of a p-polarization half-mirror is depicted inFIG. 2. Accordingly, s-polarized light is reflected by the first object-side half-mirror252as light3. The first object-side half-mirror252is positioned relative to the first object-side CR reflection boundary210such that light3is reflected by the first object-side half-mirror252onto the first object-side CR reflection boundary210where it is reflected by the outward facing reflection surface212as light4. The first object-side CR reflection boundary210is positioned relative to the first object-side external reflection boundary254such that light4is reflected by the outward facing reflection surface212onto the inward facing reflection surface256where it is reflected as light5. The first object-side external reflection boundary254is positioned relative to the first image-side external reflection boundary264such that light5is reflected by the inward facing reflection surface256onto the inward facing reflection surface266where it is reflected as light6. The first image-side external reflection boundary264is positioned relative to the first image-side CR reflection boundary220such that light6is reflected by the inward facing reflection surface266onto the outward facing reflection surface222where it is reflected as light7. The first image-side CR reflection boundary220is positioned relative to the first image-side half-mirror262such that light7is reflected by the outward facing reflection surface222onto the first image-side half-mirror262where it is reflected as light8. The first image-side half-mirror262is positioned relative to the first image-side CR reflection boundary220such that light8is reflected by the first image-side half-mirror262onto the outward facing reflection surface222where it is reflected as light9generally parallel to light1and forms a portion of the image I on the image-side24of the cloaking assembly20. It should be understood that the portion of the image I formed by light that travels from the object-side22around the cloaked region CR via the first optical path C on the first side (+X direction) of the reference optical axis26corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly20between the reference optical axis26and the optical path transition axis28.

Accordingly, light from the object O may travel from the object-side22to the image-side24via the first optical path C: object O—first object-side CR reflection boundary210—first object-side half-mirror252—first object-side CR reflection boundary210—first object-side external reflection boundary254—first image-side external reflection boundary264—first image-side CR reflection boundary220—first image-side half-mirror262—first image-side CR reflection boundary220—image I. That is, light from the object O may travel from the object-side22to the image-side24via the first optical path C: object O—reflection from the outward facing reflection surface212of the first object-side CR reflection boundary210—reflection from the first object-side half-mirror252—reflection from the outward facing reflection surface212of the first object-side CR reflection boundary210—reflection from the inward facing reflection surface256of the first object-side external reflection boundary254—reflection from the inward facing reflection surface266of the first image-side external reflection boundary264—reflection from the outward facing reflection surface222of the first image-side CR reflection boundary220—reflection from the first image-side half-mirror262—reflection from the outward facing reflection surface222of the first image-side CR reflection boundary220—image I.

Regarding the second optical path D on the first side (+X direction) of the reference optical axis26, light1′ from the object O is incident on and polarized by the first object-side half-mirror252such that one mode of light1′ is transmitted through the first object-side half-mirror252and another mode of light1′ is reflected by the first object-side half-mirror252. As noted above, a non-limiting example of the first object-side half-mirror252in the form of a p-polarization half-mirror is depicted inFIG. 2. Accordingly, p-polarized light (shown as double-dashed center lines in the figures in contrast to single-dashed center lines for the bisecting axis25and the reference optical axis26) is transmitted through the first object-side half-mirror252as light2′. The first object-side half-mirror252is positioned relative to the first object-side CR reflection boundary210such that light2′ transmitted through the first object-side half-mirror252is incident on the first object-side CR reflection boundary210where it is reflected by the outward facing reflection surface212as light3′. The first object-side CR reflection boundary210is positioned relative to the first object-side external reflection boundary254such that light3′ reflected by the outward facing reflection surface212is incident on the inward facing reflection surface256where it is reflected as light4′. The first object-side external reflection boundary254is positioned relative to the first image-side external reflection boundary264such that light4′ reflected by the inward facing reflection surface256is incident on the inward facing reflection surface266where it is reflected as light5′. The first image-side external reflection boundary264is positioned relative to the first image-side CR reflection boundary220such that light5′ reflected by the inward facing reflection surface266is incident on the outward facing reflection surface222where it is reflected as light6′ generally parallel to light1′. The first image-side CR reflection boundary220is positioned relative to the first image-side half-mirror262such that light6′ reflected by the outward facing reflection surface222is incident on the first image-side half-mirror262. As noted above, the first-image-side half-mirror262is the same type of half-mirror as the first object-side half-mirror252. Accordingly, light6′ is transmitted through the first image-side half-mirror262(as light6′) and forms a portion of the image I on the image-side24of the cloaking assembly20. It should be understood that the portion of the image I formed by light that travels from the object-side22around the cloaked region CR via the second optical path D on the first side (+X direction) of the reference optical axis26corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly20between the optical path transition axis28and the second end257of the first object-side external reflection boundary254.

Accordingly, light from the object O may travel from the object-side22to the image-side24via the second optical path D: object O—first object-side half-mirror252—first object-side CR reflection boundary210—first object-side external reflection boundary254—first image-side external reflection boundary264—first image-side CR reflection boundary220—first image-side half-mirror262—image I. That is, light from the object O may travel from the object-side22to the image-side24via the second optical path D: object O—transmittance through the first object-side half-mirror252—reflection from the outward facing reflection surface212of the first object-side CR reflection boundary210—reflection from the inward facing reflection surface256of the first object-side external reflection boundary254—reflection from the inward facing reflection surface266of the first image-side external reflection boundary264—reflection from the outward facing reflection surface222of the first image-side CR reflection boundary220—transmittance through the first image-side half-mirror262—image I.

Still referring toFIG. 2, light from the object O on the second side (−X direction) of the reference optical axis26travels from the object-side22around the cloaked region CR and forms a portion of an image ‘I’ on the image-side24via the two different optical paths C and D. Particularly, light from the object positioned above (+Y direction) the cloaking assembly20between the reference optical axis26and the optical path transition axis28′ that is incident on the cloaking assembly20(light1) travels from the object-side22around the cloaked region CR and forms a portion of an image ‘I’ via the first optical path C. Light from the object positioned above (+Y direction) the cloaking assembly20between the optical path transition axis28′ and the second end277of the second object-side external reflection boundary274that is incident on the cloaking assembly20(light1′) travels from the object-side22around the cloaked region CR and forms a portion of the image I via the second optical path D.

Regarding the first optical path C on the second side (−X direction) of the reference optical axis26, the second object-side CR reflection boundary230is positioned relative to the second object-side half-mirror272such that light1is reflected by the outward facing reflection surface232of the second object-side CR reflection boundary230onto the second object-side half-mirror272as light2. Light2is polarized by the second object-side half-mirror272such that one mode of light2is reflected by the second object-side half-mirror272and another mode of light2is transmitted through the second object-side half-mirror272. A non-limiting example of the second object-side half-mirror272in the form of a p-polarization half-mirror is depicted inFIG. 2. Accordingly, s-polarized light is reflected by the second object-side half-mirror272as light3. The second object-side half-mirror272is positioned relative to the second object-side CR reflection boundary230such that light3reflected by the second object-side half-mirror272is incident on the second object-side CR reflection boundary230where it is reflected by the outward facing reflection surface232as light4. The second object-side CR reflection boundary230is positioned relative to the second object-side external reflection boundary274such that light4reflected by the outward facing reflection surface232is incident on the inward facing reflection surface276where it is reflected as light5. The second object-side external reflection boundary274is positioned relative to the second image-side external reflection boundary284such that light5reflected by the inward facing reflection surface276is incident on the inward facing reflection surface286where it is reflected as light6. The second image-side external reflection boundary284is positioned relative to the second image-side CR reflection boundary240such that light6reflected by the inward facing reflection surface286is incident on the outward facing reflection surface242where it is reflected as light7. The second image-side CR reflection boundary240is positioned relative to the second image-side half-mirror282such that light7reflected by the outward facing reflection surface242is incident on the second image-side half-mirror282where it is reflected as light8. The second image-side half-mirror282is positioned relative to the second image-side CR reflection boundary240such that light8reflected by the second image-side half-mirror282is incident on the outward facing reflection surface242where it is reflected as light9generally parallel to light1and forms a portion of the image I on the image-side24of the cloaking assembly20. It should be understood that the portion of the image I formed by light that travels from the object-side22around the cloaked region CR via the first optical path C on the second side (−X direction) corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly20between the reference optical axis26and the optical path transition axis28′.

Accordingly, light from the object O may travel from the object-side22to the image-side24via the first optical path C: object O—second object-side CR reflection boundary230—second object-side half-mirror272—second object-side CR reflection boundary230—second object-side external reflection boundary274—second image-side external reflection boundary284—second image-side CR reflection boundary240—second image-side half-mirror282—second image-side CR reflection boundary240—image I. That is, light from the object O may travel from the object-side22to the image-side24via the first optical path C: object O—reflection from the outward facing reflection surface232of the second object-side CR reflection boundary230—reflection from the second object-side half-mirror272—reflection from the outward facing reflection surface232of the second object-side CR reflection boundary230—reflection from the inward facing reflection surface276of the second object-side external reflection boundary274—reflection from the inward facing reflection surface286of the second image-side external reflection boundary284—reflection from the outward facing reflection surface242of the second image-side CR reflection boundary240—reflection from the second image-side half-mirror282—reflection from the outward facing reflection surface242of the second image-side CR reflection boundary240—image I.

Regarding the second optical path D on the second side (−X direction) of the reference optical axis26, light1′ from the object0is incident on and polarized by the second object-side half-mirror272such that one mode of light1′ is transmitted through the second object-side half-mirror272and another mode of light1′ is reflected by the second object-side half-mirror272. As noted above, a non-limiting example of the second object-side half-mirror272in the form of a p-polarization half-mirror is depicted inFIG. 2. Accordingly, p-polarized light is transmitted through the second object-side half-mirror272as light2′. The second object-side half-mirror272is positioned relative to the second object-side CR reflection boundary230such that light2′ transmitted through the second object-side half-mirror272is incident on the second object-side CR reflection boundary230where it is reflected by the outward facing reflection surface232as light3′. The second object-side CR reflection boundary230is positioned relative to the second object-side external reflection boundary274such that light3′ reflected by the outward facing reflection surface232is incident on the inward facing reflection surface276where it is reflected as light4′. The second object-side external reflection boundary274is positioned relative to the second image-side external reflection boundary284such that light4′ reflected by the inward facing reflection surface276is incident on the inward facing reflection surface286where it is reflected as light5′. The second image-side external reflection boundary284is positioned relative to the second image-side CR reflection boundary240such that light5′ reflected by the inward facing reflection surface286is incident on the outward facing reflection surface242where it is reflected as light6′ generally parallel to light1′. The second image-side CR reflection boundary240is positioned relative to the second image-side half-mirror282such that light6′ reflected by the outward facing reflection surface242is incident on the second image-side half-mirror282. As noted above, the second image-side half-mirror282is the same type of half-mirror as the second object-side half-mirror272. Accordingly, light6′ is transmitted through the second image-side half-mirror282(as light6′) and forms a portion of the image I on the image-side24of the cloaking assembly20. It should be understood that the portion of the image I formed by light that travels from the object-side22around the cloaked region CR via the second optical path D on the second side (−X direction) of the reference optical axis26corresponds to the portion of the object O positioned above (+Y direction) the cloaking assembly20between the optical path transition axis28′ and the second end277of the second object-side external reflection boundary274.

Accordingly, light from the object O may travel from the object-side22to the image-side24via the second optical path D: object O—second object-side half-mirror272—second object-side CR reflection boundary230—second object-side external reflection boundary274—second image-side external reflection boundary284—second image-side CR reflection boundary240—second image-side half-mirror282—image I. That is, light from the object O may travel from the object-side22to the image-side24via the second optical path D: object O—transmittance through the second object-side half-mirror272—reflection from the outward facing reflection surface232of the second object-side CR reflection boundary230—reflection from the inward facing reflection surface276of the second object-side external reflection boundary274—reflection from the inward facing reflection surface286of the second image-side external reflection boundary284—reflection from the outward facing reflection surface242of the second image-side CR reflection boundary240—transmittance through the second image-side half-mirror282—image I.

In combination, i.e., light1on the first side (+X direction) and the second side (−X direction) of the reference optical axis26from the object O on the object-side22of the cloaking assembly20propagates to the image-side24via the first optical paths C: object O—reflection from the outward facing reflection surfaces212,232of the first and second object-side CR reflection boundaries210,230, respectively—reflection from the first and second object-side half-mirrors252,272—reflection from the outward facing reflection surfaces212,232of the first and second object-side CR reflection boundaries210,230, respectively—reflection from the inward facing reflection surfaces256,276of the first and second object-side external reflection boundaries254,274, respectively—reflection from the inward facing reflection surfaces266,286of the first and second image-side external reflection boundaries264,284, respectively—reflection from the outward facing reflection surfaces222,242of the first and second image-side CR reflection boundaries220,240, respectively—reflection from the first and second image-side half-mirrors262,282—reflection from the outward facing reflection surfaces222,242of the first and second image-side CR reflection boundaries220,240, respectively—image I. Also, light1′ on the first side (+X direction) and the second side (−X direction) of the reference optical axis26from the object O on the object-side22of the cloaking assembly20propagates to the image-side24via the second optical paths D: object O—transmittance through the first and second object-side half-mirrors252,272—reflection from the outward facing reflection surfaces212,232of the first and second object-side CR reflection boundaries210,230, respectively—reflection from the inward facing reflection surfaces256,276of the first and second object-side external reflection boundaries254,274, respectively—reflection from the inward facing reflection surfaces266,286of the first and second image-side external reflection boundaries264,284, respectively—reflection from the outward facing reflection surfaces222,242of the first and second image-side CR reflection boundaries220,240, respectively—transmittance through the first and second image-side half-mirrors262,282—image I.

WhileFIG. 2depicts the CR reflection boundaries210,220,230,240, the half-mirrors252,262,272,282, and the external reflection boundaries254,264,274,284as stand-alone components, it should be understood that the CR reflection boundaries210,220,230,240and the external optical component assemblies250,260,270,280may be provided as a single unit or a plurality of assembled units. For example, the external optical component assemblies250,260,270,280may be formed from a plurality of prisms that comprise the CR reflection boundaries210,220,230,240, the half-mirrors252,262,272,282, and the external reflection boundaries254,264,274,284. It should also be understood that the cloaking assembly20may cloak an object within the cloaked region CR including only the first object-side and image-side CR reflection boundaries210,220, the first object-side and image-side half-mirrors252,262, and the first object-side and image-side external reflection boundaries254,264. That is, an object positioned on the first side (+X direction) of the reference optical axis26within the cloaked region CR would be cloaked by the first object-side and image-side CR reflection boundaries210,220, first object-side and image-side half-mirrors252,262, and first object-side and image-side external reflection boundaries254,264. In the alternative, an object positioned on the second side (−X direction) of the reference optical axis26within the cloaked region CR would be cloaked by the second object-side and image-side CR reflection boundaries230,240, second object-side and image-side half-mirrors272,282, and second object-side and image-side external reflection boundaries274,284.

Referring now toFIGS. 1-5, top perspective views and a side view of cloaking devices according to embodiments described herein are shown inFIGS. 3-5. Particularly,FIG. 3is a top perspective view of an article in the form of a column ‘C’ within the cloaked region CR of the cloaking assembly10(FIG. 1) and an object ‘O’ (e.g., a person) located behind the column C on the object-side12of the cloaking assembly10in the +Y direction. The column C has a height dimension in the Z direction (increasing height in the +Z direction) greater than the height h of the cloaking device (FIG. 5).FIG. 4is a top perspective view of the column C within the cloaked region CR of the cloaking assembly20(FIG. 2) and the object O located behind the column C on the object-side22of the cloaking assembly20in the +Y direction.FIG. 5is a side view from the +Y direction of the cloaking assemblies10,20shown inFIGS. 3 and 4and shows the portion of the column C that is within the cloaked region CR is not visible and the object O located behind the column C in the +Y direction is visible to an observer viewing the cloaking assembly10in the +Y direction. Accordingly, the column C positioned within the cloaked region CR is not visible to an observer viewing the image-sides14,24of the cloaking assemblies10,20, respectively, and an image of the object O is visible to the observer viewing the image-sides14,24. Although column C inFIGS. 3-5is separate from the inward facing surfaces114,124,134,144(FIG. 3) and the inward facing surfaces214,224,234,244(FIG. 4) i.e., column C is a separate object from the cloaking assemblies10,20, it should be appreciated that column C may be structurally part of the cloaking assembly10and/or cloaking assembly20and have an outer surface that provides or is equivalent to the inward facing surfaces114,124,134,144(FIG. 1) and and/or the inward facing surfaces214,224,234,244(FIG. 2).

Referring toFIG. 6, embodiments of an A-pillar of a vehicle being cloaked by a cloaking device are shown. Particularly,FIG. 6shows a cloaking device19cloaking a portion of an A-pillar P of a vehicle V. A portion of the A-pillar P is positioned within a cloaked region (not shown) of the cloaking device19and a portion of the A-pillar P extends beyond the cloaking device and is covered with trim T. Illustrated outside of the vehicle V is a target object O in the form of pedestrian. A portion of the pedestrian O is visible through a side window of the vehicle V and a portion of the pedestrian is visible “through” the A-pillar P cloaked by the cloaking device19. The cloaking device19redirects light reflected from the pedestrian O around the A-pillar P positioned within the cloaked region of the cloaking device19and forms an image I of the pedestrian O on an image-side of the cloaking device19that is visible to an occupant of the vehicle V looking towards the pedestrian O. Accordingly, light from the pedestrian O appears to pass through the A-pillar P and a blind spot typically created by the A-pillar P is not as present as when the portion of the A-pillar P is not positioned within the cloaked region of the cloaking device19. It should be appreciated that cloaking of the A-pillar P with the cloaking device19and removing the blind spot produced by the A-pillar P is performed without the use of metamaterials, video images, cameras, sophisticated electronics, etc.

EXAMPLES

Referring now toFIGS. 7A-7E, images of an object in the form of a photograph positioned on the object-side12of the cloaking assembly10and as viewed from the image-side14simulated using a commercial software program (Zemax OpticStudio) are depicted. The cloaking assembly10with the four CR reflection boundaries110,120,130,140, four half-mirrors152,162,172,182, and four external reflection boundaries154,164,174,184, were provided in the form of four N-BK7 right angle prisms with 50 mm length sides (#32-535, Edmund Optics), four N-BK7 right angle prisms with 25 mm length sides (#32-336, Edmund Optics), and four wire-grid polarizer—cube beamsplitters (WGP-CBS) (#89-604 Edmund Optics). The outward facing reflection surfaces112,122,132,142and the inward facing reflection surfaces156,166,176,186were provided by total internal reflection within the right angle prims and the half-mirrors152,162,172,182were provided by the WGP-CBS. The cloaking assembly had a cloaking ratio of about 36%.FIG. 7Adepicts an image of the object with no misalignment)(0°) between the reference optical axis16and a viewing angle of the cloaking assembly10. That is, as used herein, the term misalignment refers to an angle defined by the reference optical axis of a cloaking assembly and a line of sight of an observer viewing the cloaking assembly from the image-side as depicted by the +Y direction in the figures (also referred to herein as a “viewing angle”).FIG. 7Bdepicts an image of the object with a 1° misalignment between the reference optical axis16and a viewing angle of the cloaking assembly10.FIG. 7Cdepicts an image of the object with a 2° misalignment between the reference optical axis16and a viewing angle of the cloaking assembly10.FIG. 7Ddepicts an image of the object with a 3° misalignment between the reference optical axis16and a viewing angle of the cloaking assembly10.FIG. 7Edepicts an image of the object with a 4° misalignment between the reference optical axis16and a viewing angle of the cloaking assembly10. As shown by the images inFIGS. 7A-7E, an image of the object on the object-side12of the cloaking assembly10can be seen clearly with up to 3° of misalignment and is still visible with up to 4° of misalignment. Accordingly, an observer can view or “see” the object O through the cloaked region CR even if the observer is not looking directly along the reference optical axis16of the cloaking assembly10.

Referring now toFIGS. 8A-8E, images of an object in the form of a photograph positioned on the object-side22of the cloaking assembly20and as viewed from the image-side24simulated using a commercial software program (Zemax OpticStudio) are depicted. The cloaking assembly20with the four CR reflection boundaries210,220,230,240, four half-mirrors252,262,272,282, and four external reflection boundaries254,264,274,284, were provided in the form of twelve N-BK7 right angle prisms with 25 mm length sides (#32-336, Edmund Optics) and four WGP-CBS (190 89-604 Edmund Optics). The outward facing reflection surfaces212,222,232,242and the inward facing reflection surfaces256,266,276,286were provided by total internal reflection within the right angle prims and the half-mirrors252,262,272,282were provided by the WGP-CBS. The cloaking assembly20had a cloaking ratio of about 44%; however, a cloaking ratio of 50% can be achieved by replacing the right angle prisms with plane mirrors.FIG. 8Adepicts an image of the object with no misalignment)(0° between the reference optical axis26and a viewing angle of the cloaking assembly20.FIG. 8Bdepicts an image of the object with a 1° misalignment between the reference optical axis26and a viewing angle of the cloaking assembly20.FIG. 8Cdepicts an image of the object with a 2° misalignment between the reference optical axis26and a viewing angle of the cloaking assembly20.FIG. 8Ddepicts an image of the object with a 3° misalignment between the reference optical axis26and a viewing angle of the cloaking assembly20.FIG. 8Edepicts an image of the object with a 4° misalignment between the reference optical axis26and a viewing angle of the cloaking assembly20. As shown by the images inFIGS. 8A-8E, an image of the object on the object-side22of the cloaking assembly20can be seen clearly with up to 2° of misalignment and is still visible with up to 3° of misalignment. Accordingly, an observer can view or “see” the object O through the cloaked region CR even if the observer is not looking directly along the reference optical axis26of the cloaking assembly20.

The cloaking devices described herein may be used to cloak vehicle articles such as a vehicle A-pillar, B-pillar, C-pillar, D-pillar, etc., and remove a blind spot caused by the vehicle article. Also, the cloaking devices described herein may be used to cloak articles such as extension cords, electrical conduit, piping, etc., in home, office and industrial environments. The terms “object,” “article,” and “item” may interchangeably refer to a visual object or image (2D or 3D) that reflects light or transmits light and the term “light from” may refer to “light reflected from” or “light transmitted from.” The terms “generally” and “about” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.