Method for generating a head up display for an aircraft using video holograms in real time with the help of sub-holograms

Patent metadata

Field	Value
Publication number	US-11460808-B2
Application number	US-202016895108-A
Country	US
Kind code	B2
Filing date	Jun 8, 2020
Priority date	Sep 1, 2006
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

A method for generating video holograms in real time for a holographic playback device comprising at least one light modulator means, into which a scene divided into object points is encoded as an entire hologram and can be seen as a reconstruction from a visibility region, which is located within a periodicity interval of the reconstruction of the video hologram, the visibility region defining a subhologram together with each object point of the scene to be reconstructed, and the entire hologram being generated from a superposition of contributions of subholograms, is characterized in that for each object point the contributions of the subholograms in the entire reconstruction of the scene can be determined from at least one look-up table.

First claim

We claim:

1. A method for generating image information representing two-dimensional information or three-dimensional information in real time, the method comprising the steps of:
dividing a scene into object points,
where the scene is observable as a reconstruction from a visibility region which is located at an eye of an observer,
determining a position of the visibility region where the eye of the observer is located by a detection and tracking system,
where position and size of a sub-hologram depend on the determined position of the visibility region and on a position of one of the object points of the scene;
where for a pre-defined normal distance of the observer from at least one light modulator, object points are either encoded at a fixed position or not at a fixed position in relation to the at least one light modulator,
where the position of the sub-hologram is determined such that a centre of the sub-hologram lies on a straight line through the object point to be reconstructed and a centre of the visibility region,
where contributions of hologram values of the sub-holograms to hologram values of an entire hologram representing the scene are retrievable from at least one look-up table for said object points and where the look-up table comprises the hologram values of the sub-holograms;
forming the hologram values of the entire hologram using a mathematical superimposition of contributions of hologram values of the sub-holograms; and
encoding the hologram values of an entire hologram in the at least one light modulator means, where the entire hologram represents the scene.

2. The method according to claim 1 where the position and viewing direction of an observer define a view of the scene and where the observer is assigned with at least one visibility region, which lies near the eyes in an observer plane, where the scene to be reconstructed is three-dimensionally decomposed into visible object points and which comprises the following process steps:
finding the position and size of the sub-hologram for each visible object point,
determination of the contributions of the corresponding sub-hologram from at least one look-up table,
repetition of these two steps for all object points, where the hologram values of the sub-holograms are mathematically superimposed so to form an entire hologram for the reconstruction of the entire scene.

3. The method according to claim 1 where at least one of hologram values of the sub-holograms and the entire hologram are modulated with brightness values or where at least one of hologram values of the sub-holograms and the entire hologram are modulated with colour values.

4. The method according to claim 3 where at least one of hologram values of the sub-holograms and the entire hologram are modulated with brightness values from at least one look-up table or where at least one of hologram values of the sub-holograms and the entire hologram are modulated with colour values from at least one look-up table.

5. The method according to claim 1 where correction values for at least one of the following are added to the hologram values of the sub-holograms and/or the entire hologram: compensating tolerances of the light modulator means caused by its position or shape, improvement of a reconstruction quality, and for correction of colour information.

6. The method according to claim 1 where the size of the sub-hologram is determined by tracing back the visibility region through the object point to the light modulator means.

7. The method according to claim 1 where for colour representation the hologram values of the sub-holograms for primary colours can be retrieved from respective look-up tables.

8. The method according to claim 1 where hologram values are converted into pixel values of the light modulator means.

9. The method according to claim 8 where the hologram values are converted into Burckhardt components or components for a two-phase encoding.

10. The method according to claim 1 for a holographic display device with a screen means, where the screen means is an optical element on to which a hologram or wave front of the scene encoded on the light modulator means is projected.

11. The method according to claim 10 where the optical element of the display device is a lens or mirror.

12. The method according to claim 1 where the hologram values of the sub-hologram of an object point are determined by computationally propagating the wave front which is emitted by the object point into the visibility region.

13. The method according to claim 1 where the look-up table is generated by determining the hologram values of the sub-hologram for each possible object point in a defined space by computationally propagating the wave front which is emitted by the object point into the visibility region and by performing a mathematical back-transformation of the wave front from the visibility region into the hologram plane where the light modulator means is situated.

14. The method according to claim 1 where the look-up table is generated by determining the hologram values of the sub-hologram for each possible object point in a defined space with the help of optimisation or approximation methods.

15. The method according to claim 1 comprising the step of encoding video holograms such that for the observer individual objects or the entire scene seemingly lie behind the light modulator.

16. The method according to claim 1 where if the object points are not encoded at a fixed position, the positions of the sub-holograms are determined as if the observer was situated in the middle in front of the light modulator, independent of where he is really situated.

17. A holographic display device comprising at least one light modulator means, wherein the holographic display device is adapted to carry out the method according to claim 1 .

Assignees

• Seereal Tech S A

Inventors

• Zschau Enrico
• Schwerdtner Armin
• Kroll Bo
• Schwerdtner Alexander

Classifications

• G03H2210/452

  into points · CPC title

• G03H2210/30

  3D object · CPC title

• G03H2226/05

  Means for tracking the observer · CPC title

• G03H1/0808

  Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific · CPC title

• G03H2001/0833

  Look up table · CPC title