Method and apparatus for controlling focal vergence of optical content

FIELD OF THE INVENTION

0001The present invention relates to the control of focal vergence of optical content. More particularly, the present invention relates to controlling the focal vergence of content generated by and/or transmitted through a display system, without necessarily applying the same changes in focal vergence to both the generated and transmitted optical content.

DESCRIPTION OF RELATED ART

0002A variety of devices may deliver some form of generated optical content. For example, a head mounted display system may generate augmented reality content, such as information regarding position, speed, landmarks, etc. and deliver that content to a viewer. Such content typically has some degree focal vergence (whether convergent, divergent, or parallel), that is, the content is generated and/or displayed so as to have a focus that corresponds to some depth or distance from the viewer. For example, augmented reality content in a head mounted display might be delivered with a focal vergence such that the content is in focus at infinity, so that to the viewer the content would appear to be at infinity (even though the display may be only a few millimeters from the viewer's eyes).

0003Certain optical devices that generate content may also deliver environmental content, for example through the use of a see-through display that allows imagery of an environment surrounding a viewer to be seen as well. Thus, both content outputted from the display and content passed through the display may be visible to a viewer at the same time, may be overlaid, etc. As a more concrete example, augmented reality content generated and delivered by a head mounted display may be overlaid onto the physical world as seen through the display.

0004In at least some instances it may be desirable to alter the focal vergence of the output content, for example so that output content appears to the viewer to be at the same depth as environment content. It may also be desirable to alter the focal vergence of output content without producing a corresponding change in the vergence of the environment content. Although it may be suitable to control or specify the focal vergence of output content during generation, or between generation and display to a viewer, certain display systems may function properly only with output content of fixed focal vergence, and/or a specific fixed focal vergence (e.g. parallel vergence corresponding to focus at infinity). For at least such systems, controlling focal vergence of output content “upstream” from the display itself may be problematic.

BRIEF SUMMARY OF THE INVENTION

0005The present invention contemplates a variety of systems, apparatus, methods, and paradigms for controlling the focal vergence of output content and/or environment content as delivered from and/or through a display.

0006In one embodiment of the present invention, an apparatus is provided that includes a first optic, a see-through display, and a second optic. The first optic is adapted to receive optical environment content and deliver the optical environment content to the see-through display. The see-through display is adapted to deliver optical output content to the second optic, and to receive the optical environment content and deliver the optical environment content to the second optic. The second optic is adapted to receive the optical output content and the optical environment content and deliver the optical output content and the optical environment content to a viewing position. The first optic is also adapted to alter the focal vergence of the optical environment content, and the second optic is adapted to alter the focal vergence of the optical environment content and to alter the focal vergence of the optical output content. These alterations to focal vergences are such that the focal vergence of the optical output content and the focal vergence of the optical environment content are alterable substantially independently.

0007The first optic and the second optic may be adapted such that the focal vergence of the optical environment content after alteration by both the first and second optics is substantially equal to the focal vergence of the optical environment content before alteration by either the first or second optics.

0008The focal vergence of the optical environment content after alteration by the first and second optics may be substantially equal to the focal vergence of the optical output content after alteration by the second optics.

0009The first optic may be adjustable so as to enable changing the alteration of focal vergence of the first optic. The second optic may be adjustable so as to enable changing the alteration of focal vergence of the second optic.

0010The apparatus may include a first actuator engaged with the first optic so as to change the alteration of focal vergence of the first optic. The apparatus may include a second actuator engaged with the second optic so as to change the alteration of focal vergence of the second optic.

0011The apparatus may include a processor in communication with the first actuator so as to control the alteration of focal vergence of the first optic. The apparatus may include a processor in communication with the second actuator so as to control the alteration of focal vergence of the second optic.

0012The apparatus may include a first actuator engaged with the first optic, a second actuator engaged with the second optic, and a processor in communication with the first and second actuators. The first optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the first optic. The second optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the second optic. The first actuator may be adapted to change the degree of alteration of focal vergence of the first optic. The second actuator may be adapted to change the degree of alteration of focal vergence of the second optic. The processor may be adapted to control the degree of alteration of focal vergence of the first optic. The processor may be adapted to control the degree of alteration of focal vergence of the second optic.

0013The apparatus may include a sensor in communication with the processor, the sensor being adapted to determine the distance to the optical environment content, and adapted to determine the focal vergence of the optical environment content prior to alteration by either of the first and second optics from the distance to the optical environment content.

0014The display may be adapted to substantially only deliver the optical output content with the focal vergence of the optical output content substantially fixed. The display may be adapted to substantially only deliver the optical output content with the focal vergence of the optical output content substantially parallel.

0015The first optic may include a liquid optical element, a deformable optical element, an electrodeformable optical element, and/or a mechanically adjustable optical element. The second optic may include a liquid optical element, a deformable optical element, an electrodeformable optical element, and/or a mechanically adjustable optical element.

0016The first optic, see-through display, and second optic may form an integrated assembly.

0017In another embodiment of the present invention, an apparatus is provided that includes a left first optic, a left see-through display, a left second optic, a right first optic, a right see-through display, and a right second optic.

0018The left first optic is adapted to receive left optical environment content and deliver the left optical environment content to the left see-through display. The left see-through display is adapted to deliver left optical output content to the left second optic, and to receive the left optical environment content and deliver the left optical environment content to the left second optic. The left second optic is adapted to receive the left optical output content and the left optical environment content and deliver the left optical output content and the left optical environment content to a left viewing position. The left first optic is adapted to alter the focal vergence of the left optical environment content. The left second optic is adapted to alter the focal vergence of the left optical environment content, and to alter the focal vergence of the left optical output content. The left first optic and left second optic are adapted such that the focal vergence of the left optical environment content after alteration by both the left first and left second optics is substantially equal to the focal vergence of the left optical environment content before alteration by either the left first or left second optics.

0019The right first optic is adapted to receive right optical environment content and deliver the right optical environment content to the right see-through display. The right see-through display is adapted to deliver right optical output content to the right second optic, and to receive the right optical environment content and deliver the right optical environment content to the right second optic. The right second optic is adapted to receive the right optical output content and the right optical environment content and deliver the right optical output content and the right optical environment content to a right viewing position. The right first optic is adapted to alter the focal vergence of the right optical environment content. The right second optic is adapted to alter the focal vergence of the right optical environment content, and to alter the focal vergence of the right optical output content. The right first optic and right second optic are adapted such that the focal vergence of the right optical environment content after alteration by both the right first and right second optics is substantially equal to the focal vergence of the right optical environment content before alteration by either the right first or right second optics.

0020The apparatus may include a left first actuator engaged with the left first optic, a left second actuator engaged with the left second optic, a right first actuator engaged with the right first optic, a right second actuator engaged with the right second optic, a processor in communication with the left first actuator, the left second actuator, the right first actuator, and the right second actuator, and a sensor in communication with the processor.

0021The left first optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the left first optic. The left first actuator may be adapted to change the degree of alteration of focal vergence of the left first optic. The left second optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the left second optic. The left second actuator may be adapted to change the degree of alteration of focal vergence of the left second optic.

0022The right first optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the right first optic. The right first actuator may be adapted to change the degree of alteration of focal vergence of the right first optic. The right second optic may be adjustable so as to enable changing the degree of alteration of focal vergence of the right second optic. The right second actuator may be adapted to change the degree of alteration of focal vergence of the right second optic.

0023The processor may be adapted to control the degree of alteration of focal vergence of the left first optic, the degree of focal vergence of the left second optic, the degree of alteration of focal vergence of the right first optic, and the degree of focal vergence of the right second optic. The sensor may be adapted to determine the distance to the optical environment content. The processor may be further adapted to determine the focal vergence of the optical environment content prior to alteration by either of the first and second optics from the distance to the optical environment content.

0024The focal vergence of the left optical environment content after alteration by the left first and left second optics may be substantially equal to the focal vergence of the left optical output content after alteration by the left second optics. The focal vergence of the right optical environment content after alteration by the right first and right second optics may be substantially equal to the focal vergence of the right optical output content after alteration by the right second optics. The see-through display may be adapted to substantially only deliver the optical output content with the focal vergence of the optical output content substantially fixed and substantially parallel.

0025In another embodiment of the present invention, a method is provided that includes receiving optical environment content from an environment to a first optic, and altering the focal vergence of the optical environment content in the first optic. The method includes delivering the optical environment content from the first optic to a see-through display, and delivering optical output content and the optical environment content from the see-through display to a second optic. The method further includes altering the focal vergence of the optical output content and the focal vergence of the optical environment content in the second optic, and delivering the optical environment content and the optical output content from the second optic to a viewing position. The focal vergence of the optical output content and the focal vergence of the optical environment content are alterable independently of one another.

0026The focal vergence of the optical environment content as received in the first optic may be substantially equal to the focal vergence of the optical environment content as delivered from the second optic. The focal vergence of the optical output content as delivered from the second optic may be substantially equal to the focal vergence of the optical environment content as delivered from the second optic.

0027The focal vergence of the output content as delivered from the see-through display may be substantially fixed. The focal vergence of the output content as delivered from the see-through display may be substantially parallel.

0028The method may include adjusting at least one of the focal vergence alteration of the first optic and the focal vergence alteration of the second optic, such that the focal vergence of the optical environment content as received in the first optic is substantially equal to the focal vergence of the optical environment content as delivered from the second optic. The method may include adjusting at least one of the focal vergence alteration of the first optic and the focal vergence alteration of the second optic, such that the focal vergence of the optical output content as delivered from the second optic is substantially equal to the focal vergence of the optical environment content as delivered from the second optic.

0029They method may include determining the focal vergence of the optical environment content prior to receiving the optical environment content from the environment to the first optic.

0030In another embodiment of the present invention, an apparatus is provided that includes first means for altering a focal vergence of optical content, means for delivering optical output content, and second means for altering said focal vergence of the optical content. The first means for altering the focal vergence are adapted to receive optical environment content, and to transmit the optical content to the means for delivering optical output content. The means for delivering optical output content are adapted to receive the optical environment content from the first means for altering the focal vergence, and to deliver the optical environment content to the second means for altering the focal vergence. The second means for altering the focal vergence are adapted to receive the optical output content and the optical environment content from the means for delivering optical output content, and to transmit the optical output content and the optical environment content to a viewing position. The focal vergence of the optical environment content as received in the first means for altering focal vergence is substantially equal to the focal vergence of the optical environment content as delivered to the viewing point.

0031The focal vergence of the optical output content as delivered to the viewing point may be substantially equal to the focal vergence of the optical environment content as delivered to the viewing point.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

0032Like reference numbers generally indicate corresponding elements in the figures.

0033<figref idref="DRAWINGS">FIG. 1A</figref> through <figref idref="DRAWINGS">FIG. 1D</figref> show example arrangements of sight lines associated with targets at different focal depths, in schematic form.

0034<figref idref="DRAWINGS">FIG. 2A</figref> and <figref idref="DRAWINGS">FIG. 2B</figref> show example arrangements of features associated with targets at different focal depths, as apparent to a viewer thereof.

0035<figref idref="DRAWINGS">FIG. 3A</figref> shows an example of focal vergence for a visual target.

0036<figref idref="DRAWINGS">FIG. 3B</figref> shows an example of focal vergence for a displayed visual target having an apparent focal depth different from an display depth thereof.

0037<figref idref="DRAWINGS">FIG. 4A</figref> shows an example of focal vergence for a displayed visual target having an apparent focal depth as modified with a first optic.

0038<figref idref="DRAWINGS">FIG. 4B</figref> shows an example of focal vergence for an environmental visual target having an apparent focal depth as modified with a first optic.

0039<figref idref="DRAWINGS">FIG. 4C</figref> shows an example of focal vergence for an environmental visual target having an apparent focal depth as modified with a first optic and a second optic.

0040<figref idref="DRAWINGS">FIG. 4D</figref> shows an example arrangement of a displayed visual target and an environmental visual target having substantially equal apparent focal depths.

0041<figref idref="DRAWINGS">FIG. 5</figref> shows an example arrangement of an apparatus according to the present invention in schematic form.

0042<figref idref="DRAWINGS">FIG. 6</figref> shows another example arrangement of an apparatus according to the present invention in schematic form, with optical elements thereof integrated into an assembly.

0043<figref idref="DRAWINGS">FIG. 7</figref> shows another example arrangement of an apparatus according to the present invention in schematic form, with left and right integrated optical assemblies.

0044<figref idref="DRAWINGS">FIG. 8</figref> shows an arrangement of an apparatus according to the present invention in perspective view.

0045<figref idref="DRAWINGS">FIG. 9</figref> shows an example method for controlling focal vergence according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

0046With reference to <figref idref="DRAWINGS">FIG. 1A</figref>, therein is shown an arrangement of sight lines for stereo vision of a target <b>112</b>A. As may be seen, left and right sight lines <b>114</b>A and <b>116</b>A may be traced from the left and right eyes <b>102</b>A and <b>104</b>A respectively to the target <b>112</b>A.

0047<figref idref="DRAWINGS">FIG. 1B</figref> shows an arrangement of sight lines to a target <b>122</b>B. The arrangement in <figref idref="DRAWINGS">FIG. 1B</figref> is at least somewhat similar to that in <figref idref="DRAWINGS">FIG. 1A</figref>. However, as may be seen by comparison of <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref>, the target <b>122</b>B in <figref idref="DRAWINGS">FIG. 1B</figref> is at a different depth or distance with respect to the viewer (represented by eyes <b>102</b>B and <b>104</b>B) than is the target <b>112</b>A from the viewer (represented by eyes <b>102</b>A and <b>104</b>A) in <figref idref="DRAWINGS">FIG. 1A</figref>. That is, the target <b>122</b>B in <figref idref="DRAWINGS">FIG. 2B</figref> is closer to the viewer than the target <b>112</b>A in <figref idref="DRAWINGS">FIG. 1A</figref>.

0048Even though the distance to the target <b>122</b>B in <figref idref="DRAWINGS">FIG. 1B</figref> is less, a similar general arrangement may be observed: left and right sight lines <b>124</b>B and <b>126</b>B may be traced from the left and right eyes <b>102</b>B and <b>104</b>B respectively to the target <b>122</b>B.

0049Turning to <figref idref="DRAWINGS">FIG. 10</figref>, an arrangement is shown therein with two targets, <b>112</b>C and <b>122</b>C. Target <b>112</b>C is at a greater distance from the viewer (as represented by eyes <b>102</b>C and <b>104</b>C) than is target <b>122</b>C.

0050The arrangement in <figref idref="DRAWINGS">FIG. 10</figref> illustrates a feature of human vision, referred to as physiological diplopia, that may occur when two targets <b>112</b>C and <b>122</b>C are visible to a viewer, but are a different depths. In the example of <figref idref="DRAWINGS">FIG. 10</figref>, it is considered that the viewer is focusing on the nearer target <b>122</b>C. As may be seen, sight lines <b>124</b>C and <b>126</b>C may be traced from the viewer's eyes <b>102</b>C and <b>104</b>C respectively to the near target <b>122</b>C.

0051However, with the viewer's eyes <b>102</b>C and <b>104</b>C focused on the near target <b>122</b>C—that is, focused at the distance corresponding to the near target <b>122</b>C—the viewer's eyes are not and cannot be focused also on the far target <b>112</b>C. As a result, sight lines <b>114</b>C and <b>116</b>C traced from the viewer's eyes <b>102</b>C and <b>104</b>C to the far target <b>112</b>C produce the appearance to the viewer of two separate images <b>118</b>C and <b>120</b>C of the far target <b>112</b>C, rather than a single image of the far target <b>112</b>C.

0052This phenomenon is referred to as physiological diplopia, as noted previously. When a viewer focuses on a target at one depth, targets at other depths may appear doubled. This is an inherent feature of normal human vision.

0053With regard to <figref idref="DRAWINGS">FIG. 1D</figref>, another example of physiological diplopia is shown therein. Near and far targets <b>122</b>D and <b>112</b>D respectively are present before the left and right eyes <b>102</b>D and <b>104</b>D respectively of a viewer. In the example of <figref idref="DRAWINGS">FIG. 1D</figref>, the viewer is focused on the far target <b>112</b>D, along sight lines <b>114</b>D and <b>116</b>D. However, the near target <b>122</b>D appears to the viewer as two images <b>128</b>D and <b>130</b>D along sight lines <b>124</b>D and <b>126</b>D respectively.

0054Turning to <figref idref="DRAWINGS">FIG. 2A</figref>, an example arrangement is shown illustrating physiological diplopia from the perspective of a viewer rather than in schematic form. In <figref idref="DRAWINGS">FIG. 2A</figref> a near target <b>222</b>A is visible in the foreground, the near target <b>222</b>A in this example taking the form of a hand. It is assumed that a viewer (not shown) is holding up a hand to serve as the near target <b>222</b>A, and focusing on that hand (near target <b>222</b>A). Behind the near target <b>222</b>A, two images <b>218</b>A and <b>220</b>A of a far target are visible. The far target is shown as a stylized x-mark, as might represent (for example) an augmented reality marker displayed at infinity by a head mounted display (not shown), though this is an example only. This arrangement in <figref idref="DRAWINGS">FIG. 2A</figref> corresponds at least somewhat to that shown in <figref idref="DRAWINGS">FIG. 10</figref>, wherein two images <b>118</b>C and <b>120</b>C of a far target <b>112</b>C appear on either side of a near target <b>122</b>C. (In practice, for the arrangement in <figref idref="DRAWINGS">FIG. 2A</figref> the images <b>218</b>A and <b>220</b>A typically may appear out-of-focus if the viewer is focused on the near target <b>222</b>A, however for clarity the images <b>218</b>A and <b>220</b>A are shown herein as sharp line art.)

0055Now with reference to <figref idref="DRAWINGS">FIG. 2B</figref>, another example arrangement is shown illustrating physiological diplopia from the perspective of a viewer. In <figref idref="DRAWINGS">FIG. 2B</figref> a far target <b>212</b>B is visible in the background; it is assumed that the viewer is focusing on the far target <b>212</b>B. In front of the far target <b>212</b>B, two images <b>228</b>B and <b>230</b>B of a near target are visible. This arrangement in <figref idref="DRAWINGS">FIG. 2B</figref> corresponds at least somewhat to that shown in <figref idref="DRAWINGS">FIG. 1D</figref>, wherein two images <b>128</b>D and <b>130</b>D of a near target <b>122</b>D appear on either side of a near target <b>112</b>D.

0056In addition, it is noted that physiological diplopia can be conveniently demonstrated by an individual so as to be understood thereby. Holding a pen in one hand at arm's length, and extending a finger of the other hand at a closer distance, a viewer may focus on either the pen or the finger. It may be observed that when the viewer focuses on the pen, two images of the finger are visible, typically on either side of the pen (though the exact position is to at least some degree a function of the relative physical positions and the particulars of each viewer's eyes). Likewise, when the viewer focuses on the extended finger two images of the pen are visible, again typically on either side of the finger.

0057As noted, physiological diplopia is a natural and inherent feature in human vision, one not readily correctable (nor would correction necessarily even be desirable).

0058Physiological diplopia is described and illustrated herein to provide an example of issues that may arise if content is displayed to a viewer with different depths (or more precisely, two different apparent depths; this distinction is addressed subsequently herein). If, for example, generated visual content is displayed to a viewer overlaid onto real-world imagery (e.g. a control or virtual object disposed in space in front of the viewer), and the generated visual is at a different depth than the real-world imagery, then physiological diplopia may result; the viewer may see either two images of the generated visual content on either side of the real-world imagery, or two images of the real-world imagery on either side of the generated visual content. Furthermore, typically only one of the generated visual content and the real-world imagery could be in-focus to the viewer at any moment.

0059Such image-doubling and out-of-focus issues may make utilizing augmented reality content problematic. For example, if the viewer is to interact with the generated visual content by (for example) using a hand to manipulate a virtual object, then if the depths of the hand and virtual object are different the viewer will (because of physiological diplopia) perceive either two images of his or her hand or two images of the virtual object. It will be understood that relying upon visual input to manipulate an object may be severely problematic for a user who cannot clearly determine the proper position of either his or her hand or the object in question. As a more concrete example, if a viewer is expected to grip a virtual object with a hand, and either the hand or the object appear to be in two different positions, the viewer may have difficulty even perceiving whether he or she is gripping the object, much less carrying out some specified manipulation.

0060It is noted that issues of physiological diplopia are presented as examples only, and that they are not intended to represent all issues that may arise from differences in depth (or apparent depth) of content.

0061Now with reference to <figref idref="DRAWINGS">FIG. 3A</figref>, therein is shown an example of focal vergence for a visual target. Focal vergence refers to the paths followed by light rays (and/or depicted as sight lines) in moving from one place to another. Focal vergence is a general term encompassing several possible cases; focal convergence refers to light rays/sight lines coming together, focal divergence refers to light rays/sight lines spreading apart, and focal parallel vergence refers to light rays/sight lines remaining parallel without coming together or spreading apart.

0062It is noted that vergence also may be applied to another feature relating to optics and vision, namely ocular vergence. Ocular vergence should not be confused with focal vergence. Ocular vergence refers to the relative orientation of eyes in binocular vision (or cameras, etc.); typically human eyes for example point at least slightly inward, toward one another, so that sight lines drawn from the center of each retina through the center of each lens and pupil will converge at some distance from the viewer. Ocular vergence is visible (but not numbered or specifically identified) in <figref idref="DRAWINGS">FIG. 1A</figref> through <figref idref="DRAWINGS">FIG. 1D</figref>. However, ocular vergence is distinct from focal vergence; the following discussion refers to focal vergence, and ocular vergence is noted here to avoid potential confusion.

0063Returning to <figref idref="DRAWINGS">FIG. 3A</figref>, an eye <b>306</b>A is shown therein. The retina <b>308</b>A and lens <b>310</b>A of the eye <b>306</b>A also are shown therein. In addition, a target <b>340</b>A is shown in the form of a stylized x-mark. The target <b>340</b>A may be substantially any visual feature; in certain places subsequently herein the stylized x-mark is used to refer to optical output content, such as virtual reality content, augmented reality content, etc. as might be generated and/or delivered by a display system. However, the arrangement of <figref idref="DRAWINGS">FIG. 3A</figref> is not necessarily specific to only optical output content; the target <b>340</b>A may represent any optical feature, whether virtual, augmented, physical, etc.

0064As may be seen, focal vergence lines <b>342</b>A are shown in <figref idref="DRAWINGS">FIG. 3A</figref> extending from the target <b>340</b>A to the lens <b>310</b>A, and then on to the retina <b>308</b>A. Focal vergence within the eye <b>306</b>A is determined at least in part by the optical properties of the eye <b>306</b>A itself, e.g. the curvature of the lens <b>310</b>A (as controlled by muscles surrounding it). The present invention does not address or directly modify focal vergence within the eye <b>306</b>A, but focal vergence lines are shown within the eye <b>306</b>A for purposes of clarity.

0065With regard to focal vergence lines <b>342</b>A between the target <b>340</b>A and the eye <b>306</b>A, it should be understood that the focal vergence for any particular target <b>340</b>A is in part a function of the distance between the eye <b>306</b>A and the target <b>340</b>A. A target <b>340</b>A that is close will exhibit greater focal divergence (or less focal convergence) than a target <b>340</b>A that is far away (other factors being equal). A target <b>340</b>A that is sufficiently distant may exhibit focal vergence that is substantially parallel, that is, light rays from the target <b>340</b>A may be approximately parallel. (This may be observed with sunlight, which—coming from a source approximately 93 million miles away—typically exhibits very nearly parallel vergence.)

0066Focal vergence and depth/distance thus are related. In at least some circumstances depth and/or distance may be determined from focal vergence, and vice versa.

0067Turning now to <figref idref="DRAWINGS">FIG. 3B</figref>, another example is shown therein of focal vergence for a visual target. In <figref idref="DRAWINGS">FIG. 3B</figref>, an eye <b>306</b>B is shown with retina <b>308</b>B and lens <b>310</b>B thereof. In addition, a display <b>334</b>B is also shown. As may be seen, a displayed output target <b>336</b>B is shown being displayed on the display <b>334</b>B. In practice the displayed output target <b>336</b>B typically may be flat along the surface of the display <b>334</b>B, but such would appear (if visible at all) only as an almost-invisibly thin profile; therefor for illustrative purposes the displayed output target <b>336</b>B is shown as a stylized x-mark centered on the surface of the display <b>334</b>B closest to the eye <b>306</b>B.

0068The displayed output target <b>336</b>B is displayed with a particular focal vergence, as shown by focal vergence lines <b>342</b>B. The focal vergence of the displayed output target <b>336</b>B is such that the displayed output target <b>336</b> is in focus, not at the distance corresponding to the surface of the display <b>334</b>B, but at a greater distance; because of this, to the viewer (whose eye <b>306</b>B is shown) the content being displayed would appear to be in a position represented by the perceived output target <b>340</b>B, shown as a smaller stylized x-mark.

0069More generally, optical content delivered by a display may be delivered with a focal vergence that does not correspond to the actual distance between the viewer and the display. Rather, as shown in <figref idref="DRAWINGS">FIG. 3B</figref>, optical content may be delivered with focal vergence such that the content appears to be at some other distance, up to and including infinity. Put another way, content may be delivered with a degree of focus corresponding to some distance other than the distance at which the screen (or other display system) is physically disposed.

0070However, although focal vergence may in principle be controlled, not all display systems are necessarily capable of controlling focal vergence in practice. For example, certain display systems require that optical content be delivered with some fixed focal vergence, that is, content is displayed with a fixed focus. Moreover, for certain display systems it may be required not only that optical content have a fixed focal vergence, but that the focal vergence be fixed at a particular value. For example, certain display systems that use optical substrates to deliver image content may function optimally only when that image content has parallel focal vergence; if the focal vergence is not parallel, images may be dispersed, may overlap, or may exhibit other undesired optical effects. For such a system therefor, any image content delivered by the display will have and indeed must have parallel focal convergence; that is, the image content is delivered always and only focused for infinity. In such instance, altering the focal vergence within the display itself may not be a viable option, since doing so may severely degrade the image quality.

0071However, as previously noted with regard to <figref idref="DRAWINGS">FIG. 1A</figref> through <figref idref="DRAWINGS">FIG. 1D</figref>, delivering optical output content from a display with a focal vergence different from that of optical environment content visible through the display may be severely problematic, resulting in double-images of optical output content and/or optical environment content.

0072As will be described and shown with regard to examples in <figref idref="DRAWINGS">FIG. 4A</figref> through <figref idref="DRAWINGS">FIG. 4D</figref> the present invention enables control of focal vergence of optical content, even when that content may be delivered with a fixed focal vergence (including but not limited to fixed parallel focal vergence) as noted above. Thus issues such as those illustrated in <figref idref="DRAWINGS">FIG. 1A</figref> through <figref idref="DRAWINGS">FIG. 1D</figref> and described with respect thereto may be alleviated or avoided altogether.

0073With regard to <figref idref="DRAWINGS">FIG. 4A</figref>, a portion of an apparatus according to the present invention is shown therein disposed in relation to a viewer. In <figref idref="DRAWINGS">FIG. 4A</figref>, an eye <b>406</b>A is shown with a retina <b>408</b>A and lens <b>410</b>A thereof. It is emphasized that the eye <b>406</b>A, retina <b>408</b>A, and lens <b>410</b>A are not intended as part of the present invention; rather the present invention may be used with a viewer's eye or eyes, and thus an eye is shown for explanatory purposes.

0074The arrangement in <figref idref="DRAWINGS">FIG. 4A</figref> also shows a display <b>434</b>A. The display <b>434</b>A delivers an output target <b>438</b>A, illustrated in the form of a stylized x-mark (though this form is an example only). The output target <b>438</b>A is delivered with a focal vergence indicated by focal vergence lines <b>432</b>A, the focal vergence corresponding to a point in space at some distance from the display <b>343</b>A and also from the eye <b>406</b>A. (As noted earlier, the output target <b>438</b>A may have, and in the example of <figref idref="DRAWINGS">FIG. 4A</figref> does have, a focal vergence such that the output target <b>483</b>A would be in focus at a position other that the actual display surface of the display <b>434</b>A. Although the output target may be displayed at a surface of the display <b>434</b>A, this is not shown in <figref idref="DRAWINGS">FIG. 4A</figref>, or likewise <figref idref="DRAWINGS">FIG. 4B</figref> through <figref idref="DRAWINGS">FIG. 4D</figref>, for purposes of simplicity.)

0075However, as described earlier, it may be desirable to change the focal vergence of optical content delivered by the display <b>434</b>A, such as the output target <b>483</b>A, thus also changing an apparent focal depth of that content. Such control of focal vergence (and thus focal depth) may be desirable even if the display <b>434</b>A can deliver only fixed focal vergence.

0076In the present invention as illustrated in <figref idref="DRAWINGS">FIG. 4A</figref>, a second optic <b>452</b>A is shown. The second optic <b>452</b>A alters the focal vergence of the output target <b>438</b>A, so that—as perceived by the viewer—the output appears in the position shown by the perceived output target <b>440</b>A, rather than in the position shown by the output target <b>438</b>A. That is, although the display delivers optical content with a focal depth shown by the output target <b>438</b>A, the viewer would actually perceive that optical content as being at a reduced focal depth shown by the perceived output target <b>440</b>A.

0077This may also be understood in comparing the focal vergence lines <b>442</b>A for the output target <b>438</b>A as delivered with the perceived focal vergence lines <b>444</b>A (shown as dashed lines in <figref idref="DRAWINGS">FIG. 4A</figref>) for the perceived output target <b>440</b>A. As may be seen, the first optic <b>452</b>A alters the path of the focal vergence lines <b>442</b>A to the path of the perceived focal vergence lines <b>444</b>A. In the example shown, the first optic <b>452</b>A is a diverging lens: light rays passing through the lens are made to diverge from their original paths. As shown the focal vergence lines <b>442</b>A, already divergent, are made to be more strongly divergent as the perceived focal vergence lines <b>444</b>A. As a result, the apparent position of the output is shifted towards the second optic <b>452</b>A, and likewise toward the display <b>434</b>A and the eye <b>406</b>A.

0078Thus as shown, the application of a lens, lens assembly, or other optic may alter the focal vergence of output delivered by a display <b>434</b>A. This alteration of focal vergence is external to the display <b>434</b>A, and thus does not directly affect the inner workings of the display <b>434</b>A; even if the display is of a sort that is limited to delivering optical content with fixed focal vergence, the focal vergence of the output nevertheless may be altered.

0079Although a diverging lens is shown as the second optic <b>452</b>A in <figref idref="DRAWINGS">FIG. 4A</figref>, this is an example only. Other lenses, including but not limited to converging lenses, may be equally suitable. Likewise, groups or assemblies of lenses or other optical elements also may be equally suitable; the present invention is not limited only to single lenses or even necessarily to lenses at all, so long as the second optic is adapted to alter the focal vergence of light and/or imagery passing therethrough. In particular, it is noted that variable optics, for example optical systems adapted to change focal vergence by varying amounts and/or in varying directions (e.g. convergence and divergence), may be suitable for use as the second optic <b>452</b>A in the present invention.

0080Through the use of a suitable second optic <b>452</b>A as shown in <figref idref="DRAWINGS">FIG. 4A</figref>, optical content delivered by the display <b>434</b>A may be made to exhibit substantially any focal vergence, and thus may be made to appear to be at substantially any focal depth, regardless of the focal vergence/focal depth at which the display <b>434</b>A itself delivers the optical content.

0081However, as may be seen now in <figref idref="DRAWINGS">FIG. 4B</figref>, the effect of a second optic according to the present invention may not apply only to optical content delivered by a display.

0082In the arrangement shown in <figref idref="DRAWINGS">FIG. 4B</figref>, an eye <b>406</b>B with retina <b>408</b>B and lens <b>410</b>B are again shown. A display <b>434</b>B is also shown (though no displayed content is illustrated), along with a second optic <b>452</b>B.

0083In addition, an environment target <b>448</b>B is shown, depicted therein as a stylized crosshair. Where an output target from <figref idref="DRAWINGS">FIG. 4A</figref> may be considered to represent displayed content delivered by the display (e.g. augmented reality data such as text, symbols, position marks, icons, etc.), the environment target <b>448</b>B in <figref idref="DRAWINGS">FIG. 4B</figref> may be considered to represent visual content external to the display <b>452</b>B. For example, people, animals, physical objects, horizon lines, etc. might be considered to be optical environment targets. Projected or displayed images that are visible without the display <b>452</b>B also may be considered environment targets, for example an image displayed on a television, monitor, cellular phone, etc. might be considered an environment target even though such an image may be generated by another display.

0084As may be seen, the second optic <b>452</b>B affects an environmental target <b>448</b>B in much the same way as the second optic <b>452</b>A in <figref idref="DRAWINGS">FIG. 4A</figref> affects an output target <b>438</b>A: the focal vergence as represented by the focal vergence lines <b>442</b>B are diverged, so that the perceived focal vergence lines <b>444</b>B cause the viewer to perceive the environment target <b>448</b>B to be in the location of the perceived environment target <b>450</b>B. That is, just as the second optic causes displayed content to appear at a reduced focal depth, so too the second optic causes external content to appear at a reduced focal depth.

0085Now with reference to <figref idref="DRAWINGS">FIG. 4C</figref>, an apparatus according to the present invention is shown therein. <figref idref="DRAWINGS">FIG. 4C</figref> illustrates an eye <b>406</b>C with retina <b>408</b>C and lens <b>410</b>C. A display <b>434</b>C and second optic <b>452</b>C of the present invention are shown, along with a first optic <b>446</b>C also of the present invention.

0086As may be seen, in the example of <figref idref="DRAWINGS">FIG. 4C</figref> the first optic <b>446</b>C serves as a “neutralizing lens” (or lens system, etc.) with respect to the second optic <b>452</b>C: the first optic <b>446</b>C provides a counter to the effect of the second optic <b>452</b>C with regard to focal vergence (and thus apparent focal depth), so that with respect to the viewer the focal vergence for an environment target <b>448</b>C without considering either the first and second optics <b>446</b>C and <b>452</b>C is substantially equal to the focal vergence of a perceived environment target <b>450</b>C. That is, optical environment content appears to be at substantially the same focal distance when having passed through both the first and second optics <b>446</b>C and <b>452</b>C as when having passed through neither the first nor the second optics <b>446</b>C and <b>452</b>C.

0087With regard more specifically to focal vergence, as may be seen the focal vergence lines <b>442</b>C are first altered by the first optic <b>446</b>C so as to be more convergent (or less divergent, in the particular example shown), pass through the see-through display <b>434</b>C, and then are made to be more divergent by the second optic <b>452</b>C. Consequently, the perceived focal vergence lines <b>444</b>C trace back to substantially the same position as the focal vergence lines <b>442</b>C. In other words, the locations of the environment target <b>448</b>C and the perceived environment target <b>450</b>C are substantially the same. Put colloquially, environmental features may be made appear “where they're supposed to”, with the changes applied thereto by the second optic <b>452</b>C being counteracted or neutralized by the first optic <b>446</b>C.

0088However, it will be understood that output content delivered by the display <b>434</b>C, the display <b>434</b>C being inward from the first optic <b>446</b>C (closer to the viewer's eye <b>406</b>C), would be unaffected by the first optic <b>446</b>C. Thus the changes in focal vergence to output content produced by the second optic <b>452</b>C would not be neutralized by the first optic <b>446</b>C.

0089Turning to <figref idref="DRAWINGS">FIG. 4D</figref>, a result of an example apparatus according to the present invention is shown. Therein is shown an eye <b>406</b>D with retina <b>408</b>D and lens <b>410</b>D. A display <b>434</b>D, first optic <b>446</b>D, and second optic <b>452</b>D of the present invention are also shown.

0090In addition, a perceived output target <b>440</b>D is shown, at a focal depth as would be perceived by the viewer. The output target itself is not shown; as shown and described with regard to <figref idref="DRAWINGS">FIG. 4A</figref> the perceived output target <b>440</b>D may be disposed at substantially any apparent focal depth, regardless of the focal depth for which the output target is delivered by the display <b>434</b>D. The output target as delivered by the display <b>434</b>D might have a focal depth of infinity, which would not be visible in <figref idref="DRAWINGS">FIG. 4D</figref> the output target thus being, apparently at least, an infinite distance to the right from the illustration). Because the focal vergence and thus focal depth of the perceived output target <b>440</b>D may be controlled substantially at will through selection of a suitable second optic <b>452</b>D according to the present invention, the original focal depth of the output target as delivered by the display <b>434</b>D is not particularly limited and thus is not shown in <figref idref="DRAWINGS">FIG. 4D</figref>.

0091Furthermore, an environment target <b>448</b>D is shown in <figref idref="DRAWINGS">FIG. 4D</figref>. The stylized crosshair shown therein is identified as both the environment target <b>448</b>D and as the perceived environment target <b>450</b>D. As previously described with regard to <figref idref="DRAWINGS">FIG. 4C</figref>, through suitable selection of a first optic <b>446</b>D (relative to the second optic <b>452</b>D) according to the present invention the perceived focal vergence to (and thus perceived focal depth of) the perceived environment target <b>450</b>D may be controlled such that the perceived environment target <b>450</b>D may appear in substantially the same place as the (unmodified) environment target <b>448</b>D.

0092Thus, as shown in <figref idref="DRAWINGS">FIG. 4D</figref> an apparatus according to the present invention may control the apparent focal vergence (and thus focal depth) of content delivered to a display, without affecting the apparent focal vergence of content passing through that display. Consequently, as illustrated in the example of <figref idref="DRAWINGS">FIG. 4D</figref>, displayed content and environmental content may be made to be in-focus at the same depth, in particular the original depth of the environmental content. This may be accomplished by the present invention regardless of the initial focal vergence of the displayed content, or the limitations of the display with regard to delivering such content.

0093However, although <figref idref="DRAWINGS">FIG. 4C</figref> and <figref idref="DRAWINGS">FIG. 4D</figref> show an arrangement for fully neutralizing the effects of the second optic on environment content through the use of the first optic, this is an example only, and the present invention is not limited only to such neutralization. Rather, the present invention more generally enables control of the focal vergence of displayed content and the focal vergence of environment content, independently of one another. While the arrangements in <figref idref="DRAWINGS">FIG. 4C</figref> and <figref idref="DRAWINGS">FIG. 4D</figref> show a particular example of such independent control, namely to change the focal vergence of the displayed content to substantially equal the focal vergence of the environment content without also changing the focal vergence of the environment content, other arrangements may be equally suitable.

0094For example, an apparatus according to the present invention may—through selection of the first and second optics—apply a net change in focus/focal vergence to both displayed and environmental content. As a more concrete example, the apparatus might serve not only to align the focus of displayed content with the focus of environmental content but also to apply an overall focus correction, e.g. to compensate for nearsightedness, farsightedness, etc.

0095In summary, an apparatus according to the present invention may independently control focal vergence (and focal depth) for both displayed and environmental content. One example application is to substantially align the focal vergence of displayed content with the focal vergence of environmental content, thus reducing or eliminating issues such as those relating to physiological diplopia. However, the present invention is not limited only to such an application.

0096Turning to <figref idref="DRAWINGS">FIG. 5</figref>, therein an apparatus according to the present invention is shown in schematic form. The apparatus includes a first optic <b>546</b>, a second optic <b>552</b>, and a see-through display <b>534</b>. The see-through display <b>534</b> is engaged with the first and second optics <b>546</b> and <b>552</b> such that light and/or image content from the environment may be received by the first optic <b>546</b> and delivered to the display <b>534</b>, passed through the display, and delivered to the second optic <b>552</b>. In addition, light and/or image content delivered by the display <b>534</b> may be delivered to the second optic <b>552</b>.

0097The present invention is not particularly limited with regard to the specifics of the see-through display <b>534</b>, a first optic <b>546</b>, and a second optic <b>552</b>.

0098The see-through display <b>534</b> is adapted to deliver visual content for receipt by a viewer. The see-through display <b>534</b> may be fully transparent, or may filter light in some fashion, block some light, modify some or all light passing therethrough, etc.

0099As illustrated in <figref idref="DRAWINGS">FIG. 5</figref>, the entire display <b>534</b> is disposed geometrically between the first and second optics <b>546</b> and <b>552</b>. However, this is an example only, and other arrangements may be equally suitable. For example, it is noted that certain displays include multiple elements, such as an image generator, a transmission unit for moving the light from the image generator to a position for output, a decoupler to deliver the output in a viewable form, etc. It is not required that the display <b>534</b> or any particular physical components thereof be disposed in any particular geometric relationship with regard to the first and second optics <b>546</b> and <b>552</b>. An image generator might be some considerable distance from either the first or the second optics <b>546</b> and <b>552</b>, even if (for example) a decoupler were physically disposed between the first and second optics <b>546</b> and <b>552</b>. Nor is it required that environment imagery physically pass through a display <b>534</b> (though this also is not prohibited); an open space carrying (for example) scanning lasers that “draw” images on a retina also may be considered a transparent display for purposes of the present invention.

0100So long as output light and/or imagery is delivered by the display <b>534</b> and passes through the second optic <b>552</b> into a viewable position, and environment light and/or imagery passes through the first and second optics <b>546</b> and <b>552</b> into that viewable position, so as to function as shown and described herein, the physical arrangement of the elements of the present is not particularly limited.

0101A wide range of devices and systems may be suitable for use as a display <b>534</b> according to the present invention. For example, optical output content may be generated by systems including but not limited to light emitting diodes (LED), organic light emitting diodes (OLED), plasma screen panels (PDP), liquid crystal displays (LCD), etc. Likewise, the use of projected or transmitted displays, where the viewed surface is essentially a passive screen for an image projected or otherwise transmitted after being generated elsewhere, may also be suitable. Other arrangements including but not limited to systems that display images directly onto a user's eyes also may be equally suitable. Either digital or analog display technologies may be suitable. Similarly, optical output content may be delivered to a viewer/viewable position by systems including but not limited to light pipes, optical substrates, direct display (e.g. disposing an active LED screen in the line of sight), scanning lasers, etc.

0102A wide range of devices also may be suitable for the first and second optics <b>546</b> and <b>552</b>. For example, individual lenses or other optical elements of various forms, materials, etc. may be suitable. Although <figref idref="DRAWINGS">FIG. 5</figref> shows a first optic <b>546</b> as a convex (converging) lens and a second optic <b>552</b> as a concave (diverging) lens this is an example only, and other arrangements may be equally suitable.

0103Assemblies of lenses or other optical elements also may be suitable for use as first and second optics <b>546</b> and <b>552</b>. Although for simplicity the singular term “optic” is used to refer to elements <b>546</b> and <b>552</b>, the present invention is not particularly limited to the number of optical components in either the first or the second optic <b>546</b> and <b>552</b>.

0104Variable optical elements and/or assemblies may be suitable for use as first and second optics <b>546</b> and <b>552</b>. For example, first and/or second optics <b>546</b> and <b>552</b> that may vary in their optical properties, such as degree and direction of vergence (e.g. convergence or divergence), may be suitable. In particular, arrangements wherein the first and/or second optics <b>546</b> and <b>552</b> are adjustable so as to change the alteration of focal vergence thereof may be useful for at least some embodiments. Such adjustability may enable tailoring changes in focal vergence based on local conditions (e.g. distance to environment content), individual viewer characteristics (e.g. nearsightedness), etc.

0105Suitable optical elements for use as and/or in the first and/or second optics <b>546</b> and <b>552</b> may include but are not limited to liquid optical elements, deformable optical elements, electrodeformable or otherwise electroresponsive optical elements, and mechanically variable optical assemblies. Also, the first and second optics <b>546</b> and <b>552</b> are not required to be identical or even similar in form or composition; an apparatus according to the present invention might use a single liquid lens for the first optic <b>546</b> but an assembly of multiple rigid lenses for the second optic <b>552</b>.

0106It is noted that the present invention may be assembled piecemeal, and/or as an add-on to an existing system. For example, an existing display <b>534</b> might be retrofitted with suitable first and second optics <b>546</b> and <b>552</b> according to the present invention.

0107Turning to <figref idref="DRAWINGS">FIG. 6</figref>, although the present invention may be configured using individual elements, and/or as retrofitted elements, the present invention also may be configured as an integrated assembly <b>636</b> as shown therein. For example, the first optic <b>646</b> and second optic <b>652</b> may be physically and/or optically integrated with the display <b>634</b> so as to form a single module, optical unit, etc. Such arrangements may for at least certain embodiments enable the present invention to be made particularly compact, reliable, etc. However, this is an example only, and other arrangements may be equally suitable.

0108Now with reference to <figref idref="DRAWINGS">FIG. 7</figref>, an apparatus according to the present invention may include numerous elements other than the display, first optic, and second optic as thus far described herein. For example, as shown in <figref idref="DRAWINGS">FIG. 7</figref> the example apparatus therein includes an integrated display assembly <b>754</b>A with a first optic <b>746</b>A, a display <b>734</b>A, and a second optic <b>752</b>A, at least somewhat similar to the arrangement shown in <figref idref="DRAWINGS">FIG. 6</figref>. However, the integrated display assembly <b>754</b>A in <figref idref="DRAWINGS">FIG. 7</figref> also includes a first actuator <b>756</b>A adapted to adjust the optical properties of the first optic <b>746</b>A, e.g. changing the focal length thereof (thus changing the degree and/or direction by which the first optic <b>746</b>A alters focal vergence); this presumes the first optic <b>746</b>A is adjustable, as noted previously. The integrated display assembly <b>754</b>A further includes a second actuator <b>758</b>A adapted to adjust the optical properties of the second optic <b>752</b>A.

0109In addition, the apparatus in <figref idref="DRAWINGS">FIG. 7</figref> includes a second integrated display assembly <b>754</b>B. The integrated display assembly <b>754</b>B includes a first optic <b>746</b>B, display <b>734</b>B, second optic <b>752</b>B, first actuator <b>756</b>B, and second actuator <b>758</b>B similar to the integrated display assembly <b>754</b>A already described. Such a configuration might be suited for example for an arrangement wherein each of a viewer's eyes is provided with an integrated display assembly <b>754</b>A and <b>754</b>B, such as might be the case for a stereo display system.

0110The arrangement of <figref idref="DRAWINGS">FIG. 7</figref> also includes a processor <b>760</b> in communication with the integrated display assemblies <b>754</b>A and <b>754</b>B, and with the first actuators <b>756</b>A and <b>756</b>B and second actuators <b>758</b>A and <b>758</b>B therein. Such an arrangement may for example facilitate control of the first actuators <b>756</b>A and <b>756</b>B and second actuators <b>758</b>A and <b>758</b>B, and control of the first optics <b>746</b>A and <b>746</b>B and second optics <b>752</b>A and <b>752</b>B thereby. The processor <b>760</b> may also be in communication with and/or in control of the displays <b>734</b>A and <b>734</b>B, depending on the particulars of an embodiment.

0111Further, the arrangement of <figref idref="DRAWINGS">FIG. 7</figref> includes sensors <b>762</b>A and <b>762</b>B in communication with the processor <b>760</b>. Sensors may be useful in providing a variety of data for facilitating operation of the apparatus. For example, sensors <b>762</b>A and <b>762</b>B may be adapted to determine the distance between the viewer or display <b>734</b>A and <b>734</b>B and optical environment content; for embodiments wherein the focal vergence of displayed content is to be matched to the focal vergence of environment content, data on what the focal vergence of the environment might usefully be obtained by such sensors <b>762</b>A and <b>762</b>B. In addition or instead, sensors <b>762</b>A and <b>762</b>B might be adapted to determine where the viewer is looking within the field of view, or to perform other functions that may be useful in displaying and/or manipulating optical content.

0112Now with regard to <figref idref="DRAWINGS">FIG. 8</figref>, an apparatus according to the present invention may be implemented in many embodiments taking many forms. One such form is illustrated as an example in <figref idref="DRAWINGS">FIG. 8</figref>, in perspective view. Therein, the apparatus <b>866</b> is configured in the form of a head mounted display resembling a pair of glasses. The apparatus shown therein includes integrated display assemblies <b>854</b>A and <b>854</b>B, arranged such that when the apparatus <b>866</b> is worn the integrated display assemblies <b>854</b>A and <b>854</b>B would be disposed near to and in front of a viewer's eyes. Though not visible in <figref idref="DRAWINGS">FIG. 8</figref>, the integrated display assemblies <b>854</b>A and <b>854</b>B may include therein first optics, displays, second optics, first and second actuators, etc.

0113The apparatus <b>866</b> also includes a processor <b>860</b>, and sensors <b>862</b>A and <b>862</b>B. A body <b>864</b> supports the integrated display assemblies <b>854</b>A and <b>854</b>B, processor <b>860</b>, and sensors <b>862</b>A and <b>862</b>B so as to make the apparatus readily wearable in a useful fashion. It is emphasized that the arrangement shown in <figref idref="DRAWINGS">FIG. 8</figref> is an example only, and that other configurations may be equally suitable.

0114Turning to <figref idref="DRAWINGS">FIG. 9</figref>, therein an example embodiment of a method according to the present invention is shown, in flow chart form.

0115In the method according to <figref idref="DRAWINGS">FIG. 9</figref>, optical environment content is received <b>982</b> from the environment to a first optic. As has been previously described herein with regard to apparatus embodiments, optical environment content may represent content not generated within the display system. For example, for a head mounted display optical environment content might include a view of the physical world surrounding the wearer of the head mounted display.

0116Continuing in <figref idref="DRAWINGS">FIG. 9</figref>, the focal vergence of the optical environment content is altered <b>984</b> in the first optic. Depending on the embodiment and other particulars, the focal vergence may be made more convergent or more divergent, and in varying amounts.

0117The optical environment content is delivered <b>986</b> from the first optic to a see-through display.

0118The optical environment content is then delivered <b>988</b> from the see-through display (e.g. passing therethrough) to a second optic. In addition, optical output content is also delivered <b>988</b> from the see-through display (e.g. generated and/or outputted by the display) to the second optic.

0119The focal vergence of both the optical output content and the optical environment content is altered <b>990</b> in the second optic.

0120The optical output content and optical environment content is then delivered <b>992</b> from the second optic to a viewing point. For example, the viewing point might be a location for a viewer to place his or her eyes so as to view the optical output content and optical environment content.

0121The method as shown in <figref idref="DRAWINGS">FIG. 9</figref> is then complete. However, additional steps and/or repetition of steps already shown may be equally suitable for at least certain embodiments.

0122Likewise, as previously noted the present invention may include actuation of variable first and second optics, processor control of such actuation (e.g. wherein steps of altering focal vergence may be actively controlled within the processor), sensing of various parameters, etc.

0123In particular, different embodiments may vary in the particulars of the alteration of focal vergences by the first and second optics in steps <b>984</b> and <b>990</b> (though other variations are not excluded).

0124For example, the focal vergence of the optical environment content as received in said first optic may be substantially equal to the focal vergence of said optical environment content as delivered from the second optic. That is, the focal vergence of the optical environment content may be substantially the same both before the first and second optics and after the first and second optics.

0125In addition or instead, the focal vergence of the optical output content as delivered from the second optic may be substantially equal to the focal vergence of the optical environment content as delivered from the second optic. That is, the focal vergences of the optical output content and optical environment content as delivered to the viewing point may be substantially the same.

0126The focal vergence of the output content as delivered from the see-through display may be substantially fixed. The focal vergence of the output content as delivered from the see-through display also or alternately may be substantially parallel.

0127The above specification, examples, and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.