Adjusting contrast in an optical system

An improved object projection system provides an observer with a surrounding background that has adjustable contrast levels relative to an object. A transmissive polarizer and a reflective polarizer change relative orientations. The change in orientation causes the level of light passing through the transmissive polarizer to change. In one system, the transmissive polarizer is placed in front of an object. A light source is placed in front of the object and behind the transmissive polarizer. A reflective polarizer is placed behind the object. The reflective polarizer provides the surrounding background for the object. A light source illuminates the object and the reflective polarizer. The object emits reflected light, which travels through the transmissive polarizer. Light from the reflective polarizer is transmitted to the transmissive polarizer. The level of light transmitted depends on the orientation of a transmissive axis of the transmissive polarizer to a reflective axis of the reflective polarizer.

SURROUNDING BACKGROUND

This disclosure relates to adjusting the contrast in optical systems. In particular, this disclosure relates to adjusting the contrast between an image and the surrounding background.

2. Surrounding Background

Special effects designers use a real image projection system to generate an image of an object. For example, a real image projection system may be used to create a floating real image of an object that appears to an observer from nowhere. Generally, the floating real image is surrounded by a surrounding background. The surrounding background may be intrusive and interfere with observing the floating real image of an object. In this case, it is desirable to remove the surrounding background from the floating real image of an object. Further, present real image projection systems suffer from stray light rays bouncing off the hardware such as the optical elements associated with the real image projection system or the surrounding background such as a ceiling or a floor. The stray light rays are problematic because these rays make the hardware visible to an observer. The viewing of the hardware may ruin the perception of an observer of the floating real image of the object.

A common way of addressing these above problems is to make the enclosure black, such as using black velvet, so that reflected light and stray light rays are absorbed and appear invisible to an observer. However, there is a need for an improved process for producing images that highly contrast to the surrounding background and provide other improvements over present systems.

SUMMARY

An improved optical system, as disclosed herein, uses optical polarizers where changing the relative orientation of the optical polarizers adjust the contrast level between an object and its surrounding background. For instance, special effects design engineers for studios or movie houses may utilize this improved optical system for creating a floating image of an object, such as a ghost, while being able to actively control the intensity level of the surrounding background. Other applications include convenience stores, train stations, or other locations where an image of an object needs to be displayed on a remotely located wall or other surface.

In one aspect, an improved optical system includes a reflective polarizer, a transmissive polarizer and a light source. The reflective polarizer is a material having a reflective axis that reflects light that vibrates in the same plane as the reflective axis. Light aligned along the reflective axis is reflected from the reflective polarizer and appears as the surrounding background for the object. The transmissive polarizer is a material having a transmissive axis that transmits light vibrating in the same plane as the transmissive axis. Light aligned along the transmissive axis is transmitted from the transmissive polarizer. In this system, an object is placed in front of the reflective polarizer. The transmissive polarizer is placed in front of the object. A light source illuminates the object and the reflective polarizer. Light received at the object reflects toward the reflective polarizer and the transmissive polarizer. Light received at the reflective polarizer aligned with the reflective axis is reflected from the reflective polarizer back toward the transmissive polarizer. Light received at the transmissive polarizer aligned with the transmissive axis passes through the transmissive polarizer to an observer. Light received from the reflective polarizer passes through the transmissive polarizer to an observer depending on the orientation of the transmissive axis to the reflective axis.

If the transmissive axis and the reflective axis are oriented substantially orthogonal to each other, the effect created is a dark surrounding background. In this orientation, if the object is lightly colored, the object has maximum optical contrast to the surrounding background. In this same orientation, if the object is dark-colored, the object has minimum optical contrast to the surrounding background.

If the transmissive axis and the reflective axis are oriented substantially parallel, the effect created is a light surrounding background. In this orientation, if the object is lightly-colored, the object has minimum optical contrast to the surrounding background. In this same orientation, if the object is dark-colored, the object has maximum optical contrast to the surrounding background.

In yet another aspect, rotation of the transmissive axis with respect to the reflective axis controls the intensity of the surrounding background. The effect is that a user can gradually transition from a dark to a light surrounding background by rotating the transmissive axis relative to the reflective axis.

In another aspect, an optical lens, a polarization maintaining reflective surface, and a beam splitter are added to the above optical system. The additional optical elements provide for a real image of the object to be distally located from the object. An optical lens is, for example, a polarization maintaining lens such as a Fresnel lens. The polarization maintaining surface is a first surface mirror. The beam splitter is, for example, a 50% transmissive, 50% reflective light surface. In this system, a reflective polarizer is placed in front of an object. A light source illuminates the object and the reflective polarizer. An optical lens is placed behind an object but in front of a mirror. A transmissive polarizer is placed in front of the mirror. A light source illuminates the object and the reflective polarizer. Light reflected from the object travels to a beam splitter. Light arriving at the reflective polarizer along the reflective axis is reflected toward the beam splitter.

Light passes through the beam splitter to the optical lens. The optical lens transmits light toward the polarization maintaining surface. Light reflected from the polarization maintaining surface is reflected back to the beam splitter. Light reflected from the beam splitter travels to the transmissive polarizer distally located from the object. At the transmissive polarizer, a real image of the object passes through the transmissive polarizer. The intensity of the real image of the object is a substantially fixed intensity level substantially independent of transmissive axis to reflective axis orientation. Similar to the embodiment described above, rotating the transmissive to the reflective axis causes the surrounding background of the object to change from dark to light.

In yet another embodiment, an improved projection system produces a larger effective display area for the real image of the object. The larger effective display area is the result of creating two geographically separate locations, i.e., one for the object and the other for the real image of the object. The geographic separation of the object and real image of the object creates a 2-fold increase in area for the real image of the projection system. In this system, there are sweet spots, one for the object and the other for the real image of the object that are distally located from each other. Light illuminates the object. Light reflected from the object passes through a beam splitter. A mirror reflects light arriving from the beam splitter back toward the beam splitter. Light arriving at the beam splitter travels away from the object to another geometric location. Thereby, the beam splitter and the mirror working in cooperation create a real image of the object at a location geographically separate from the object.

The foregoing and other objects, features, and advantages of the present disclosure will be become apparent from a reading of the following detailed description of exemplary embodiments thereof, which illustrate the features and advantages of the disclosure in conjunction with references to the accompanying drawing Figures.

DETAILED DESCRIPTION

FIG. 1is a schematic diagram of one embodiment wherein a reflective polarizer and a transmissive polarizer are utilized to adjust the contrast level between an object and a surrounding background. An improved optical system includes reflective polarizer11, transmissive polarizer15and light source10.

Reflective polarizer11is a material having a reflective axis9that reflects light that vibrates in the same plane as the reflective axis9. Light aligned along reflective axis9is reflected from reflective polarizer and appears as the surrounding background for object12. For example, reflective polarizer11is manufactured by International Polarizer having a polarization maintaining surface, a pressure sensitive adhesive, and a polarizing film.

In another example, reflective polarizer11is a glass plate having one surface deposited with silver for reflecting light and for maintaining incident light polarity. The opposite surface of the glass plate deposited with a pressure sensitive adhesive, and laminated with polarizing element. Polarizing element creates a reflective axis9. Polarizing element may be a thin-film material of type Hn-32 manufactured by 3M. In yet another example, polarizing element may have a first surface coated with a polarization maintaining reflective material. In the alternative, reflective polarizer11may be an aluminum on glass polarizer manufactured by Moxtek, Inc. In this alternative, one surface of this glass polarizer is coated with a polarization maintaining reflective material such as silver paint like Krylon 1401 silver.

Transmissive polarizer15is a material having transmissive axis17that transmits light vibrating in the same plane as transmissive axis17. Light aligned along transmissive axis17passes through transmissive polarizer15. In one aspect, transmissive polarizer15is a glass plate deposited on one side with a polarizing material such as Moxtek to create transmissive axis17. In another aspect, polarizing material may be an organic film such as Hn-32 from manufacturer 3M.

Light source10is a light providing illumination for object12. Light source10may be a movie house production light such as ETC source four providing 750 watts of illumination.

In this system, light source10illuminates object12and reflective polarizer11. Light arriving at object12is reflected toward reflective polarizer11and transmissive polarizer15. Light from object12that aligns with the transmissive axis17of transmissive polarizer15passes through transmissive polarizer15. Light arriving at reflective polarizer11aligned along reflective axis9is reflected to transmissive polarizer15. Reflective polarizer11reflects light along reflective axis9. Transmissive polarizer15receives light from reflective polarizer11.

If reflective axis9and transmissive axis17are substantially orthogonal, light from reflective polarizer11is reflected, blocked, or absorbed by transmissive polarizer15. The effect is that object12appears against a dark surrounding background. Thus, this orientation provides a maximum contrast level between the object and the surrounding background. The brightness of object12is a substantially fixed intensity, and independent of a relative transmissive axis17orientation because the reflected light from the object is not polarized. The brightness of object12substantially depends on the intensity of light source10.

FIG. 2is a schematic diagram of one embodiment using a reflective polarizer and a transmissive polarizer for producing an object with a low contrast level relative to the surrounding background.

This embodiment describes using reflective polarizer11and transmissive polarizer15ofFIG. 1where transmissive polarizer15is rotated 90 degrees. Reflective polarizer11has a reflective axis9. Transmissive polarizer15has transmissive axis17. In this aspect, reflective axis9and transmissive axis17are substantially parallel. The effect is that object12appears against a light surrounding background. If the object is lightly-colored, this relative orientation provides a low contrast level between the object and the surrounding background.

In another aspect, the rotation of the relative orientation of transmissive axis17to reflective axis9controls the contrast level between the object and its surrounding background. The effect is that a user can gradually transition from a dark to a light surround background by rotating transmissive axis17relative to reflective axis9. For example, rotating transmissive axis17to reflective axis9from substantially orthogonal to substantially parallel transitions from a dark surrounding background to a minimum contrast level (light surrounding background) between the object and the surrounding background). In this aspect, the object is lightly-colored.

FIG. 3is a schematic diagram of one embodiment using a reflective polarizer, a polarization maintaining lens, a beam splitter, a mirror and a transmissive polarizer for producing a real image of an object with a high contrast level relative to the surrounding background.

For example, beam splitter21is a 50% transmissive, 50% reflective mirror. In another example, beam splitter may have any ratio of transmissive to reflective properties. Further, in this example, optical lens30is a polarization maintaining lens such as a Fresnel lens. Reflective surface23, for example, is a mirror or like device.

In this system, light source10illuminates reflective polarizer11and object12. The light reflected from object12travels to beam splitter21. Light incident on reflective polarizer11along reflective axis9is reflected to beam splitter21. Light traveling through beam splitter21passes through optical lens30. Optical lens30focuses light traveling to reflective surface23. Optical lens30may be a Fresnel lens. Reflective surface23may be a mirror or like device. In another aspect, optical lens30and reflective surface23may be combined into one optical element such a reflective Fresnel lens.

Light bounces off reflective surface23and passes back through optical lens30to beam splitter21. Beam splitter21transmits light to transmissive polarizer15. Light arriving along transmissive axis17is transmitted. In this aspect, light from reflective axis9is blocked. Real image of the object25appears against a dark surrounding background27. For a lightly-colored real image of the object, this aspect provides the effect of a high contrast level between the real image of the object25and surrounding background27.

FIG. 4is a schematic diagram of one embodiment using a reflective polarizer, a polarization maintaining lens, a beam splitter, a mirror and a transmissive polarizer for producing a real-image of an object with a low contrast level relative to the surrounding background.

Reflective axis9and transmissive axis17are substantially parallel (approximately zero degrees) relative to each other. This embodiment functions similar to the one described above inFIG. 3except for the above-mentioned relative orientation of reflective axis9and transmissive axis17. Light reflected from reflective polarizer11is transmitted through transmissive axis17. Object12appears against light surrounding background29. This relative orientation of transmissive axis17to reflective axis9provides a low contrast level between real image of the object25that is lightly-colored and light surrounding background29.

In another aspect, as transmissive axis17to reflective axis9rotates from substantially orthogonal (substantially 90 degrees) to substantially zero degrees, the effect is that the surrounding background gradually transitions from dark to light. In addition, reflective axis9and transmissive axis17capture and nullify stray light rays in an optical system for hiding the optical elements or hardware of a real image projection system.

FIG. 5is a schematic diagram forFIGS. 3 and 4real image projection systems using polarized baffles. A polarized baffle is a reflective polarizer such as previously discussed in above embodiments. To further nullify stray light rays, one or more polarized baffles are strategically deployed within the real image projection system. Polarized baffles60,65,75,70are placed in strategic locations to absorb stray light or reflections from optical elements or hardware. Optical elements and hardware may include beam splitters, reflective polarizers, mirrors, and the like.

Polarized baffles prevent stray light rays appearing in the surrounding background. Polarized baffles are placed such that the polarizing baffle appears black when the polarized baffle is viewed through the transmissive polarizer15. It should be noted that these are exemplary locations for the polarized baffles. The polarized baffles may be repositioned to remove stray light rays.

For example, polarized baffle60located behind source10absorbs stray light from optical elements such as source10. In another example, polarized baffle75located between source10and beam splitter20absorbs stray light rays, for example, from source10before striking beam splitter21. In yet another example, polarized baffle65located between optical lens30and beam splitter21absorbs stray light from optical elements, for example, optical lens30and reflective surface23. In another example, polarized baffle70located between transmissive polarizer15and beam splitter21absorbs stray light from optical elements, for example, object12and source20.

Polarized baffles prevent stray light rays making their way to transmissive polarizer15which can prevent an observer from seeing a real image of the object25mysteriously disappear and reappear. Post optical elements80are strategically deployed to further differentiate the real image of the object and the surrounding background.

In one aspect, post optical element80is a scrim or a mirror. In one example, post optical element80passes real image of object25but not stray light rays and/or optical artifacts. The effect is to create for an observer an illusion of a real object.

In another example, post optical element80may be a 50% transparent and 50% reflective mirror. The effect of using a reflective mirror is to block stray light and assist in separating the surrounding background from object. In this aspect, real image of the object25appears to an observer as an illusion.

In another example, if post optical element80is a mirror, an observer will view real image of the object25without casting any reflection in the mirror. Thus, real image of the object25not casting a reflection in the mirror strengthens the illusion to an observer that real image of the object25is actually a ghost or an apparition.

FIG. 6is a schematic diagram of one embodiment of a flat mirror real image projection system producing a real image of an object with a high contrast level relative to the surrounding background. Light travels from source10illuminating object12and reflective polarizer11. The principal axis of the optical system is denoted as97. Light reflected along reflective axis travels through lens30to reflective surface23. Reflective surface23receives light from object12and from polarized reflector11. Light from object12passes through transmissive polarizer producing a real image of object25. Light from reflective polarizer11is blocked, reflected, or absorbed because transmissive axis17and reflective axis9are orthogonal. The effect created is a dark surrounding background1for real image of object25. A high contrast level is achieved for a lightly-colored real image of the object25compared to surrounding background27.

FIG. 7is a schematic diagram of one embodiment of a flat mirror real image projection system producing a real image of an object with a low contrast level relative to the surrounding background. Light travels from source10illuminating object12and reflective polarizer11. Light from object travels through lens30to reflective surface23. Light reflected along reflective axis9travels through lens30to reflective surface23. Reflective surface23transmits light from object12and from polarized reflector11. Light received from object12passes through transmissive polarizer15to produce real image of the object25. Light reflected along reflective axis9passes through transmissive polarizer15because transmissive axis17and reflective axis9are substantially parallel to each other. The effect creates a light background29for real image of the object25. A low contrast level is achieved for a lightly-colored real image of the object25compared to surrounding background29.

FIG. 8is a schematic diagram of one embodiment of a flat mirror real image projection system with a beam splitter producing a real image of an object with a high contrast level relative to the surrounding background. In this example, beam splitter21is a 50% transmissive, 50% reflective mirror. In another example, beam splitter21may be any ratio of transmissive to reflective coefficient mirror-like surface. Light from source10illuminates object12and polarized reflector11. Light aligned along reflective axis9travels through beam splitter21and lens30. Afterwards, light travels to reflective surface23. Light reflected from object12travels through beam splitter and lens30to reflective surface23. Light from reflective surface23travels back through lens30to beam splitter21. Light from object is reflected by beam splitter to produce a real image of object25through transmissive polarizer15. Reflected light from reflective polarizer11is blocked by transmissive polarizer because transmissive axis17and reflective axis9are substantially orthogonal to each other. The effect created is a dark surrounding background27for real image of object25. For a lightly-colored object, a high contrast level is achieved between real image of object25and surrounding background27.

In an alternative of the present aspect, optical lens30and reflective surface23may be replaced with a polarization maintaining retro-reflective material. Retro-reflective materials, for example, produced by manufacturers such as 3M Company Safety Division may be used. In yet another alternative, polarization maintaining retro-reflective materials may include spherical and corner cube techniques.

FIG. 9is a schematic diagram of one embodiment of a flat mirror real image projection system with a beam splitter producing a real image of an object with a low contrast level relative to the surrounding background. For example, beam splitter21is 50% transmissive and 50% reflective mirror surface. In this system, light travels from source10illuminating object12and polarized reflector11. Light aligned with reflective axis9is reflected through beam splitter21and lens30. Afterwards, light travels to reflective surface23. Light reflected from object12passes through beam splitter21, lens30to reflective surface23. Light from reflective surface23passes through lens30to beam splitter21. Light from object12is reflected by beam splitter21producing real image of object25at transmissive polarizer15. Light from reflective polarizer11reflected by beam splitter passes through transmissive polarizer15because transmissive axis17and reflective axis9are substantially parallel to each other. The effect created is light surrounding background29for real image of object25. For a lightly-colored object, a low contrast level is achieved between real image of object25and surrounding background29.

In an alternative of the present aspect, optical lens30and reflective surface23may be replaced with a polarization maintaining retro-reflective material. Retro-reflective materials, for example, produced by manufacturers such as 3M Company Safety Division may be used. In yet another alternative, polarization maintaining retro-reflective materials may include spherical and corner cube techniques.

FIG. 10is a schematic diagram of one embodiment of a parabolic mirror real image projection system producing a real image of an object with a high contrast level relative to the surrounding background. Parabolic mirror90is used to generate a real image. Object12is placed at the focal point of parabolic mirror90. Reflective polarizer11is positioned outboard of object12outboard of focal point95of parabolic mirror90. Light travels from source10illuminating object12and reflective polarizer11. Light reflected along reflective axis9travels to parabolic mirror surface100. Light reflected from object12travels to parabolic mirror surface100. Parabolic mirror surface100reflects light from object12and from polarized reflector11. Light received from object12passes through transmissive polarizer15appearing as real image of the object25. Light received from reflective polarizer11is blocked, reflected, or absorbed at transmissive polarizer15because transmissive axis17and reflective axis9are substantially orthogonal to each other. The effect created is a dark surrounding background27for real image of the object25. A high contrast level is achieved for a real image of the object25and surrounding background27.

FIG. 11is a schematic diagram of one embodiment of a parabolic mirror real image projection system producing a real image of an object with a low contrast level relative to the surrounding background. Parabolic mirror90is used to generate a real image. Object12is placed at the focal point of parabolic mirror90. Reflective polarizer11is positioned outboard of object12outboard of focal point95of parabolic mirror90. Light travels from source10illuminating object12and reflective polarizer11. Light reflected along reflective axis9travels to parabolic mirror surface100. Light reflected from object12travels to parabolic mirror surface100. Parabolic mirror surface100reflects light from object12and from polarized reflector11. Light received from object12passes through transmissive polarizer15appearing as real image of the object25Light received from reflective polarizer11is blocked, reflected, or absorbed at transmissive polarizer15because transmissive axis17and reflective axis9are substantially parallel to each other. The effect created is a light surrounding background27for real image of the object25. This effect creates a low contrast level for real image of the object25that is lightly colored compared to surrounding background27.

FIG. 12is a schematic diagram of one embodiment of a parabolic mirror real image projection system with a beam splitter producing a real image of an object with a high contrast level relative to the surrounding background. Parabolic mirror90is used to generate a real image of the object12. In one aspect, beam splitter21is a 50% transmissive and 50% reflective mirror surface. Light travels from source10illuminating object12and polarized reflector11. Light reflected aligning with reflective axis9passes through beam splitter21to parabolic mirror surface100. Light reflected from object12travels through beam splitter21to parabolic mirror surface100. Parabolic mirror90transmits reflected light from object12and from polarized reflector11back to beam splitter21. Light from object12passes through transmissive polarizer15to produce real image of object25. Light from reflective polarizer11is blocked, reflected, or absorbed at transmissive polarizer15because transmissive axis17and reflective axis9are substantially orthogonal to each other. The effect created is a dark surrounding background27for real image of the object25. This effect creates a high contrast level between real image of the object25and surround background27.

FIG. 13is a schematic diagram of one embodiment of a parabolic mirror real image projection system with a beam splitter producing a real image of an object with a low contrast level relative to the surrounding background. Parabolic mirror90is used to generate a real image of the object12. In one aspect, beam splitter21is a 50% transmissive and 50% reflective mirror surface. Light travels from source10illuminating object12and polarized reflector11. Light reflected aligning with reflective axis9passes through beam splitter21to parabolic mirror surface100. Light reflected from object12travels through beam splitter21to parabolic mirror surface100. Parabolic mirror90transmits reflected light from object12and from polarized reflector11back to beam splitter21. Light from object12passes through transmissive polarizer15to produce real image of object25. Light from reflective polarizer11passes through transmissive polarizer15because transmissive axis17and reflective axis9are substantially parallel to each other. The effect is creating a light surrounding background29for real image of object25.

FIG. 14is a schematic diagram of one embodiment of a double clam shell real image projection system producing a real image of an object with a high contrast level relative to the surrounding background. In this aspect, two parabolic mirror surfaces are attached together. Two parabolic mirror surfaces are placed facing each other. Opening105is created in one mirror. Object12is placed in the center of a parabolic mirror surface. Reflective polarizer11is placed under object12on mirror surface. Transmissive polarizer is placed over opening105. Light travels from light source10through transmissive polarizer15illuminating object12and reflective polarizer11. Light from object12passes through transmissive polarizer15producing real image of the object25. Light reflected along reflective axis9travels back to transmissive polarizer15. Light from reflective polarizer11is blocked by transmissive polarizer15because transmissive axis17and reflective axis9are substantially orthogonal to each other. The effect created is a dark surrounding background27for real image of object25.

FIG. 15is a schematic diagram of one embodiment of a double clam shell real image projection system producing a real image of an object with a low contrast level relative to the surrounding background. In this aspect, two parabolic mirror surfaces are attached together. Two parabolic mirror surfaces are placed facing each other. Opening105is created in one mirror. Object12is placed in the center of a parabolic mirror surface. Reflective polarizer11is placed under object12on mirror surface. Transmissive polarizer is placed over opening105. Light travels from light source10through transmissive polarizer15illuminating object12and reflective polarizer11. Light from object12passes through transmissive polarizer15producing real image of the object25. Light reflected along reflective axis9travels back to transmissive polarizer15. Light from reflective polarizer11passes through transmissive polarizer15because transmissive axis17and reflective axis9are substantially parallel to each other. The effect created is a dark surrounding background27for real image of object25. The effect creates a high contrast level between a lightly colored real image of object25and surrounding background27.

FIG. 16is a schematic of a prior art real projection system utilizing a minimized sweet spot between an object and a geometrically separated real image of the object. Sweet spot130of the optical system is the distortion free volume useful for the generation of a real image. Sweet spot130is the volume occupied by object12, real image of the object25and the space between object12and real image of the object25. Since object12and real image25are geographically adjacent, ½ of sweet spot130is reserved for object12and ½ of the sweet spot130is reserved for real image of the object25. In this system, there is only one sweet spot.

FIG. 17is a schematic of a maximized sweet spot real projection system producing a real image of an object with a high contrast level and where the object and the real image of the object are geographically separated. In this aspect, a beam splitter is used to generate a real image projection system with two non-geographically adjacent sweet spots. Each of these sweet spots140,150is the same size as the sweet spot from theFIG. 16sweet spot. The object sweet spot140is the same size as the real image sweet spot150. In this example, object12is located at sweet spot140. In one aspect, sweet spot140is focal point of reflective surface23.

Light from source10illuminates object12and reflective polarizer11. Light from object12passes through beam splitter21and lens30. Light aligned with reflective axis9passes through beam splitter21and lens30. In this aspect, reflective surface23is a concave mirror. Light from object12reflected by beam splitter21to transmissive polarizer15produces real image of object25in real image sweet spot150. Light from reflective surface23and from reflective axis9is blocked because transmissive polarizer15and reflective polarizer11are substantially orthogonal to each other. The effect is to produce a dark background27for real image of object25. The effect creates for a lightly colored real image of the object25a high contrast level compared to its surrounding background27.

In yet another instance, sweet spot150is used for projecting real image of the object25and sweet spot140is used for object12. In yet another aspect, reflective surface23and lens30are replaced by a laminate composite of a Fresnel lens and a mirror.

FIG. 18is a schematic of a maximized sweet spot real image projection system producing a real image of an object with a low contrast level and where the object and the real image of the object are geographically separated. In this aspect, a beam splitter is used to generate a real image projection system with two non-geographically adjacent sweet spots. Each of these sweet spots140,150is the same size as the sweet spot from theFIG. 16sweet spot. The object sweet spot140is the same size as the real image sweet spot150. In this example, object12is located at sweet spot140. In one aspect, sweet spot140is focal point of reflective surface23.

Light from source10illuminates object12and reflective polarizer11. Light from object12passes through beam splitter21and lens30. Light aligned with reflective axis9passes through beam splitter21and lens30. In this aspect, reflective surface23is a concave mirror. Light from object12reflected by beam splitter21to transmissive polarizer15produces real image of object25in real image sweet spot150. Light from reflective surface23from reflective axis9is blocked because transmissive polarizer15and reflective polarizer11are substantially parallel to each other. The effect is to produce a light background29for real image of the object25. The effect creates for a lightly colored real image of the object25a low contrast level compared to its surrounding background29.

In yet another instance, sweet spot150is used for projecting real image of the object25and sweet spot140is used for object12. In yet another aspect, reflective surface23and lens30are replaced by a laminate composite of a Fresnel lens and a mirror.

FIG. 19is a flow chart for one embodiment for controlling the contrast level of an object relative to the surrounding background. A transmissive polarizer is placed in front of an object as indicated in block510. A light source is placed in front of the object and behind the transmissive polarizer as indicated in block520. A reflective polarizer is placed behind the object as indicated in block530. A light source illuminates the object as indicated in block540. The same intensity of reflected light from the object transmitted by the transmissive polarizer independent of a rotation of the transmissive axis to the reflective axis as indicated in block550.

The transmissive polarizer may be rotated to adjust the intensity of reflected light received from the reflective polarizer at the transmissive polarizer as indicated in block560. In one alternative, the transmissive axis is rotated to a ninety degree orientation relative to the reflective axis to achieving a maximum contrast level between the object and the surrounding background. In another alternative, the transmissive axis is rotated from substantially zero degrees to ninety degrees orientation relative to the reflective axis for changing the surrounding background from light to dark.

In yet another alternative, the reflective axis is rotated to a substantially ninety degree orientation relative to the transmissive axis for achieving a maximum contrast level between an object and the surrounding background. In yet another alternative, the transmissive axis is aligned substantially parallel to the reflective axis for achieving a minimum contrast level between the object and the surrounding background.

Information as herein shown and described in detail is fully capable of attaining the above-described object of the disclosure and the present embodiment of the disclosure, and is, thus, representative of the subject matter, which is broadly contemplated by the present disclosure. The scope of the present disclosure fully encompasses other embodiments which may become obvious to those skilled in the art, and is to be limited, accordingly, by nothing other than the appended claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described embodiment and additional embodiments that are known to those of ordinary skill in the art are hereby expressly incorporated by reference and are intended to be encompassed by the present claims.

Moreover, no requirement exists for a device or method to address each and every problem sought to be resolved by the present disclosure, for such to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. However, one skilled in the art should recognize that various changes and modifications in form and material details may be made without departing from the spirit and scope of the inventiveness as set forth in the appended claims. No claim herein is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.”