Holographic Display Phase Coding Iterative Fourier Algorithm
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Solution Overview
Problem
Holographic display devices face reconstruction errors due to disturbing light and limitations in encoding methods, particularly with phase-modulating spatial light modulators, which hinder high-quality reconstruction of three-dimensional scenes.
Innovation Solution
A holographic imaging display system that employs a modified iterative Fourier transformation algorithm, utilizing two imaging means and a filter to compute and control phase values on a phase modulator, allowing for improved encoding and reconstruction of three-dimensional scenes by approximating complex values in a transformation area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phase encoding is used in a phase modulator to reconstruct a three-dimensional scene, then the brightness of the reconstruction is improved, but reconstruction errors occur due to disturbing light and encoding method limitations
Solution Approach 1:
The patent implements an iterative Fourier transformation algorithm that uses feedback loops to continuously refine the phase encoding values. The algorithm transforms the phase-encoded wave front, compares it with the desired reference wave front, and adjusts the encoding values in subsequent iterations to minimize reconstruction errors while maintaining brightness enhancement from phase encoding.
Solution Approach 2:
The patent performs preliminary computation of complex phase and amplitude values for multitude of object points before actual hologram encoding. The iterative algorithm pre-calculates corrected phase encoding values that account for expected reconstruction errors, allowing the phase modulator to be configured optimally before the actual reconstruction process begins.
2Ease of manufacture
If two-phase encoding is used to encode a computer-generated hologram, then the encoding process is simplified, but the reconstruction quality deteriorates due to local offset errors
Solution Approach 1:
The patent transitions from simple two-phase encoding to a multi-dimensional iterative optimization approach. By adding the iterative Fourier transformation dimension, the system maintains the simplicity of phase-only encoding while correcting precision errors through repeated transformations between the object space and Fourier space, effectively solving the local offset problem without abandoning phase encoding simplicity.
Solution Approach 2:
The patent dynamically adjusts phase encoding parameters through iterative computation. Instead of using fixed two-phase encoding values, the algorithm continuously refines the phase values assigned to each pixel based on the reconstructed wave front quality, allowing optimization of reconstruction precision while maintaining the phase-only modulation approach.
3Ease of operation
If optical transformation is performed from the phase modulator into the visibility region, then the wave front can be imaged, but additional optical means must be added and existing ones modified
Solution Approach 1:
The patent makes the phase modulator serve multiple functions: it acts as both the hologram encoder and the transformation element. By computing and storing the complex-valued hologram data that directly encodes the desired wave front transformation, the phase modulator eliminates the need for separate optical transformation components, reducing system complexity while maintaining imaging capability.
Solution Approach 2:
The patent replaces physical optical transformation components with computational methods. Instead of using additional lenses, mirrors, or optical elements to perform the wave front transformation, the system uses iterative Fourier transformation algorithms to compute the correct phase encoding values that achieve the desired optical transformation effect through diffraction alone.
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 enhances reconstruction quality by minimizing errors and improving the encoding process, enabling high-quality, error-free reconstruction of three-dimensional scenes in holographic displays.
Implementation Method 1
A phase modulator, or phase-modulating SLM, is an electronic medium which serves to control the phase of a wave front by way of modulating an illuminating wave front emitted by one or multiple independent light sources
Implementation Method 2
an optical transformation of the wave front—which corresponds e.g. with a Fresnel transformation or with a Fourier transformation—takes place from the phase modulator into the visibility region
Implementation Method 3
a filter whose aperture or an image of the aperture defines in the plane of the screen a transformation area
Implementation Method 4
at least one illumination means for generating a sufficiently coherent illuminating wave front
Implementation Method 5
The reconstruction of the 3D scene is generated by diffraction of sufficiently coherent light at the controllable pixels
Data Source
AI summary
A holographic projection display for reconstructing a 3D-scene and a coding method that indicates an improvement of the control value of coding through an iterative Fourier transformations-algorithm are disclosed. The display includes a reproduction system including at least two reproducing means. First reproduction means for reproducing the illuminating means and for the Fourier transformation of actual wave fronts modulated in the phase modulator follow a second reproduction means, that functions as a screen. The plane of the screen is a Fourier transformation plane for calculations with the iterative Fourier transformation-algorithm and the plane of the phase modulator is the other Fourier transformation plane.