Heads-up and heads-down displays employing holographic stereograms

• US 5,663,815 A
• Filed: 06/07/1995
• Issued: 09/02/1997
• Est. Priority Date: 02/14/1994
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Volchok, William J., Molteni, William J.
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US08/480,192
• Time in Patent Office: 818 Days
• Field of Search: 359/9, 359/21, 359/22, 359/23, 359/25, 359/26, 359/13, 359/14, 359/900
• US Class Current: 359/13
• CPC Class Codes: G02B 2027/0109 comprising details concerning the making of holograms
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0129 comprising devices for correcting parallax
• CPC Class Codes: G02B 2027/0134 of stereoscopic type
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/0145 creating an intermediate image
• CPC Class Codes: G02B 27/0103 comprising holographic elements
• CPC Class Codes: G03H 1/265 Angle multiplexing; Multichannel holograms G03H1/268 takes precedence
• CPC Class Codes: G03H 1/268 Holographic stereogram
• CPC Class Codes: G03H 2001/0413 for recording transmission holograms
• CPC Class Codes: G03H 2001/0415 for recording reflection holograms
• CPC Class Codes: G03H 2001/043 Non planar recording surface, e.g. curved surface
• CPC Class Codes: G03H 2001/2223 Particular relationship between light source, hologram and observer
• CPC Class Codes: G03H 2001/2231 Reflection reconstruction
• CPC Class Codes: G03H 2001/2234 Transmission reconstruction
• CPC Class Codes: G03H 2001/2236 Details of the viewing window
• CPC Class Codes: G03H 2001/2257 Straddling the hologram
• CPC Class Codes: G03H 2001/226 Virtual or real
• CPC Class Codes: G03H 2001/269 Two and more than two steps recording process
• CPC Class Codes: G03H 2210/42 from real object, e.g. using 3D scanner
• CPC Class Codes: G03H 2210/441 : Numerical processing applied to the object data other than numerical propagation synthesizing propagation G03H1/0808
• CPC Class Codes: G03H 2210/454 : into planes
• CPC Class Codes: G03H 2222/22 : Spatial coherence
• CPC Class Codes: G03H 2222/42 : Reference beam at recording stage
• CPC Class Codes: G03H 2222/54 : Convergent beam
• CPC Class Codes: G03H 2270/21 : Curved bearing surface

Abstract

Heads-Up and heads-down displays employing holographic stereograms are provided. The stereograms can be oriented perpendicular to the user'"'"'s line of sight (the 90° case) or at angle to the line of sight (the "non-90° case"). The stereograms are produced using a three-step process in which a series of two-dimensional perspective views are prepared, a H₁ hologram is prepared from the two-dimensional perspective views, and a H₂ hologram is prepared from the H₁ hologram. For the non-90° case, the two-dimensional perspective views are oriented at an angle relative to the plane of the H₁ hologram during the preparation of that hologram. Similarly, during the preparation of the H₂ hologram for this case, the H₂ hologram is oriented at an angle relative to the H₁ hologram. In this way, the viewing slits generated by the holographic stereogram are located in the vicinity of the user'"'"'s eyes for the non-90° case as is desired. In certain embodiments, the two-dimensional perspective views are transformed prior to being recorded on the H₁ hologram.

Claims

1. A method for preparing and using a holographic stereogram having a perceived image contained therein viewable along a user'"'"'s line of sight when said holographic stereogram is orientated on a plane nonorthogonal to said line of sight, the method comprising the steps of:

(a) preparing a set of two-dimensional perspective views of an object;

(b) transforming said set of two-dimensional perspective views to form a set of transformed views said transformation performed such that

(i) a user'"'"'s eves define vertical and horizontal axes;

(ii) the tilt of the holographic stereogram is defined by angles α and

γ

, where α

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the vertical axis, γ

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the horizontal axis, and α and

γ

both equal to 90°

corresponds to an untilted stereogram;

(iii) the set of perspective views is defined by a set of β

angles, where β

equal to zero corresponds to the straight ahead view of the object, positive β

'"'"'s correspond to movements to the left relative to the object, and negative β

'"'"'s correspond to movements to the right relative to the object;

(iv) each two-dimensional perspective view comprises a set of intensity values in (x'"'"',y'"'"') coordinates;

(v) each transformed view comprises a set of intensity values in (x",y") coordinates; and

(vi) the intensity values in (x",y") coordinates are transformed into intensity values in (x",y") coordinates in step (b) in accordance with the following equations;

space="preserve" listing-type="equation">x"=(x'"'"'·

cos (β

)·

sin (α

)+y'"'"'·

cos (α

)·

cos (γ

-β

))/(sin (α

)·

sin (γ

-β

))

space="preserve" listing-type="equation">y"=y'"'"'

where at least one of α and

γ

is different from 90°

; and

(c) preparing the holographic stereogram from the set of transformed views such that the perceived image is substantially orthogonal to the line of sight and is translated relative to the center of the holographic stereogram in a direction of the line of sight.

2. The method of claim 1 where α

is different from 90°

.

3. The method of claim 1 where γ

is different from 90°

.

4. The method of claim 1 both α

and γ

are different from 90°

.

5. The method of claim 1 wherein a line of sight intersects the center of the holographic stereogram and the transforming of step (b) causes translation of the image along the line of sight.

6. The method of claim 1 wherein a line of sight intersects the center of the holographic stereogram and the transforming of step (b) causes the image to be translated both along the line of sight and in a direction orthogonal to the line of sight.

7. A method for preparing and using a holographic stereogram having a perceived image contained therein viewable along a user'"'"'s line of sight when said holographic stereogram is orientated on a plane nonorthogonal to said line of sight, the method comprising the steps of:

(a) preparing a set of two-dimensional perspective views of an object;

(b) transforming said set of two-dimensional perspective views to form a set of transformed views said transformation performed such that

(i) a user'"'"'s eyes define vertical and horizontal axes;

(ii) the tilt of the holographic stereogram is defined by angles α and

γ

, where α

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the vertical axis, γ

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the horizontal axis, and α and

γ

both equal to 90°

corresponds to an untilted stereogram;

(iii) the line of sight intersects the center of the holographic stereogram;

(iv) the image is to be perceived by the user to be;

at a distance Z'"'"' from the center of the holographic stereogram along the line of sight, where a positive Z'"'"' corresponds to a translation of the image towards the user,

at a distance Y'"'"' from the center of the holographic stereogram in a direction parallel to the vertical axis, where a positive Y'"'"' corresponds to a translation of the image upward as seen by the user, and

at a distance X'"'"' from the center of the holographic stereogram in a direction parallel to the horizontal axis, where a positive X'"'"' corresponds to a translation of the image to the fight as seen by the user;

(v) the set of perspective views is defined by a set of β

angles, where β

equal to zero corresponds to the straight ahead view of the object, positive β

'"'"'s correspond to movements to the left relative to the object, and negative β

'"'"'s correspond to movements to the fight relative to the object;

(vi) each two-dimensional perspective view comprises a set of intensity values in (x'"'"',y'"'"') coordinates;

(vii) each transformed view comprises a set of intensity values in (x",y") coordinates; and

(viii) the intensity values in (x'"'"',y'"'"') coordinates are transformed into intensity values in (x",y") coordinates in step (b) in accordance with the following equations;

space="preserve" listing-type="equation">x"=((x'"'"'+X'"'"')·

cos (β

)·

sin (α

)+Z'"'"'·

sin (α

)·

sin (α

)-(y'"'"'+Y'"'"')·

cos (α

)·

cos (γ

-β

)/sin (α

)·

sin (γ

-β

))

space="preserve" listing-type="equation">y"=y'"'"'+Y'"'"'

where at least one of α and

β

is different from 90° and

at least one of Z'"'"', Y'"'"', and X'"'"' is different from zero; and

(c) preparing the holographic stereogram from the set of transformed views such that the perceived image is substantially orthogonal to the line of sight and is translated relative to the center of the holographic stereogram in a direction of the line of sight.

8. A method for preparing a holographic stereogram for viewing by a user, the user'"'"'s eyes defining (i) a line of sight which intersects the center of the holographic stereogram, (ii) a vertical axis, and (iii) a horizontal axis, comprising the steps of:

(a) preparing a set of two-dimensional perspective views of an object, each of said two-dimensional perspective views comprising a set of intensity values in (x'"'"',y'"'"') coordinates;

(b) preparing a set of transformed views comprising a set of intensity values in (x",y") coordinates in accordance with the following equations;

space="preserve" listing-type="equation">x"=((x'"'"'+X'"'"')·

cos (β

)·

sin (α

)+Z'"'"'·

sin (β

)·

sin (α

)-(y'"'"'+Y'"'"')·

cos (α

)·

cos (γ

-β

))/(sin (α

)·

sin (γ

-β

))

space="preserve" listing-type="equation">y"=y'"'"'+Y'"'"'

where;

(i) α

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the vertical axis,

(ii) γ

is measured from the user'"'"'s line of sight in the plane containing the line of sight and the horizontal axis,

(iii) α and

γ

both equal to 90°

correspond to the holographic stereogram being orthogonal to the line of sight,

(iv) Z'"'"' is measured from the center of the holographic stereogram along the line of sight with a positive Z'"'"' being towards the user,

(v) Y'"'"' is measured from the center of the holographic stereogram in a direction parallel to the vertical axis with a positive Y'"'"' being upward as seen by the user, and

(vi) X'"'"' is measured from the center of the holographic stereogram in a direction parallel to the horizontal axis with a positive X'"'"' being to the right as seen by the user, and

(vii) at least one of Z'"'"', Y'"'"', and X'"'"' is different from zero; and

(c) preparing the holographic stereogram from the set of transformed views.

9. The method of claim 8 wherein at least one of α

and γ

is different from 90°

.

10. The method of claim 8 wherein the set of two-step dimensional perspective views is prepared by computer and step (b) is performed as the perspective views are prepared.

11. A method of preparing and using a holographic stereogram having an image contained therein which is tilted with respect to the holographic stereogram such that an intersection of a line of sight with a plane of the holographic stereogram is non-orthogonal but where an intersection of a line of sight with the image is orthogonal with the line of sight, said method comprising the steps of:

preparing a series of two-dimensional images of an object to be displayed from multiple horizontal perspectives;

transforming the two-dimensional images to create transformed images which are transformed along a vertical axis;

distorting the two-dimensional images horizontally to compensate for keystone distortion in the first hologram;

producing a first hologram using the transformed images by sequentially projecting each of the transformed images through imaging optics onto a vertical segment of a holographic recording plate; and

making a second hologram from a projected image of the first hologram, where the image reconstructed when said second hologram is exposed to appropriate reconstructive illumination appears to occupy a plane angled with respect to the plane occupied by the second hologram.

12. The method of claim 11 wherein the step of transforming the two-dimensional images comprises continuously varying two-dimensional transformation along a vertical axis of each of the two-dimensional perspective images.

13. The method of claim 11 wherein the step of transforming the two-dimensional images comprises altering the two-dimensional images which are defined in a two-dimensional (x'"'"',y'"'"') coordinate system to transformed images defined in a two-dimensional (x",y") coordinate system where centers (x'"'"',y'"'"'=0,0 and x",y"=0,0) of these coordinate systems are coincident.

14. The method of claim 13 the step of transforming the two-dimensional images further comprises transforming the two-dimensional images such that x"=x'"'"' and y"=y'"'"' when a first tilt angle of the stereogram measured from a +z axis in a yz plane equal ninety degrees and a second tilt angle of the stereogram measured from a +z axis in the xz plane equals ninety degrees.

15. The method of claim 13 the step of transforming the two-dimensional images further comprises transforming the two-dimensional images according to the following formula

16. The method of claim 13 the step of transforming the two-dimensional images further comprises transforming the two-dimensional images according to the following formula

17. The method of claim 13 the step of transforming the two-dimensional images further comprises transforming the two-dimensional images according to the following formula

18. A method of preparing and using a holographic stereogram from a preexisting set of two-dimensional images where the holographic stereogram has an image contained therein which is tilted with respect the holographic stereogram such that the intersection of a line of sight with a plane of the holographic stereogram is non-orthogonal but where the image of the hologram appears to be orthogonal with the line of sight, said method comprising the steps of:

digitizing the preexisting set of two-dimensional images to create digitized images;

transforming the two-dimensional images by relocating the intensity values of the digitized images on a pixel-by-pixel basis to create transformed images having vertical transformation;

producing a first hologram using the transformed images by sequentially projecting the transformed images onto a diffusion screen, and moving a movable a slit aperture in front of a holographic recording plate to image the contents of the diffusion screen thereon; and

making a second hologram from a projected image of the first hologram, where the image reconstructed when said second hologram is exposed to appropriate reconstructive illumination appears to occupy a plane angled with respect to the plane occupied by the second hologram.

19. A method of preparing and using a hologram stereogram having an image contained therein which is tilted with respect to the holographic stereogram such that an intersection of a line of sight with a plane of the holographic stereogram is non-orthogonal but where an intersection of a line of sight with the image is orthogonal with the line of sight, said method comprising the steps of:

preparing a series of two-dimensional images of an object to be displayed from multiple horizontal perspectives;

transforming the two-dimensional images to create transformed images by altering the two-dimensional images which are defined in a two-dimensional (x'"'"',y'"'"') coordinate system to transformed images defined in a two-dimensional (x",y") coordinate system where centers (x'"'"',y'"'"'=0,0 and x",y"=0,0) of these coordinate systems are coincident;

producing a first hologram using the transformed images by sequentially projecting each of the transformed images through imaging optics onto a vertical segment of a holographic recording plate; and

making a second hologram from a projected image of the first hologram where, the image reconstructed when said second hologram is exposed to appropriate reconstructive illumination appears to occupy a plane angled with respect to the plane occupied by the second hologram.