Hologram Encoding Correcting Volume Grating Angle Selectivity
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Solution Overview
Problem
The existing methods for encoding holograms in light modulation devices suffer from intensity variations due to the angle selectivity of volume gratings, leading to uneven light transmission across the virtual observer window, affecting the reconstruction of three-dimensional scenes.
Innovation Solution
The method involves calculating and applying correction values based on the reciprocal of the volume grating's diffraction efficiency to adjust the amplitudes of wavefronts or subholograms, ensuring consistent light transmission across the virtual observer window by accounting for the angle selectivity of volume gratings in the hologram calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If volume gratings are used in the beam path to enable holographic reconstruction, then the hologram can be displayed with three-dimensional depth, but intensity variations occur due to angle selectivity of the volume gratings
Solution Approach 1:
The patent applies preliminary correction by calculating and storing correction values that compensate for the angle selectivity of volume gratings before the hologram is displayed. These correction values are pre-computed based on the known optical properties of the volume gratings and are applied to the hologram data in advance, ensuring uniform light transmission across the virtual observer window during reconstruction.
Solution Approach 2:
The patent modifies the amplitude parameters of the hologram by multiplying them with correction values that account for the angle-dependent diffraction efficiency of volume gratings. This parameter change compensates for the intensity variations that would otherwise occur due to the angle selectivity of the volume gratings, resulting in uniform light transmission across different viewing angles.
2Area of stationary object
If the virtual observer window is made larger than the eye pupil to provide a broader viewing region, then more observers can view the hologram simultaneously, but the intensity variations caused by angle selectivity are amplified
Solution Approach 1:
The patent applies different correction values to different regions of the hologram corresponding to different areas of the virtual observer window. Each region is corrected according to its specific angle selectivity characteristics, ensuring that intensity uniformity is maintained across the entire large viewing area despite the amplified angle variations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures that light is transmitted with approximately equal efficiency across the virtual observer window, reducing intensity variations and enhancing the reconstruction of three-dimensional scenes by correcting for the angle selectivity of volume gratings.
Implementation Method 1
the angle selectivity of at least one volume grating arranged downstream in the beam path of the light modulation device is taken into account in a hologram calculation
Implementation Method 2
a light modulation device, which has an arrangement of pixels as modulation elements
Data Source
AI summary
A hologram is constructed from individual subholograms assigned to corresponding encoding regions in a light modulation device and respectively assigned to an object point of the object to be reconstructed with the hologram. With a virtual observer window, a defined viewing region is provided through which a reconstructed scene in a reconstruction space is observed by an observer. A complex value of a wavefront for each individual object point is calculated in the virtual observer window. Each individual amplitude of a complex value of a wavefront in the virtual observer window is subsequently multiplied by a correction value with which a correction of the angle selectivity of at least one volume grating arranged downstream in the beam path of the light modulation device is carried out. The corrected complex values determined in this way for all object points are summed and transformed into the hologram plane of the light modulation device.