Spatial Filtered SLM Display for Multi-Field Interference Control
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Solution Overview
Problem
Existing display systems struggle to increase the number of image fields displayed per unit time, limiting motion smoothness and enabling techniques such as noise averaging and eyebox expansion.
Innovation Solution
A display system utilizing a spatial filter positioned in the Fourier plane of a spatial light modulator (SLM) to prevent coherent interference between multiple image fields encoded in different portions of the spatial-frequency domain, allowing simultaneous display of multiple image fields using a single modulation pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single modulation pattern is used to encode multiple image fields in different portions of the spatial-frequency domain, then the number of image fields displayed per unit time increases, but coherent interference between the image fields occurs
Solution Approach 1:
A spatial filter is introduced as an intermediary element positioned in the Fourier plane to selectively pass different portions of the spatial-frequency domain corresponding to different image fields. This mediator prevents coherent interference by allowing only specific spatial frequency components to reach the viewer at any given time, enabling multiple image fields to be encoded in a single modulation pattern without mutual interference.
Solution Approach 2:
The spatial-frequency domain is segmented into multiple distinct portions, each corresponding to a different image field. The spatial filter is configured with multiple regions that selectively transmit light from specific portions of the Fourier transform of the modulation pattern. This segmentation allows independent control and transmission of multiple image fields simultaneously encoded in one modulation pattern.
2Productivity
If the Fourier transform is divided into multiple portions for different image fields, then multiple image fields can be displayed simultaneously, but the device complexity increases due to the spatial filter with multiple regions
Solution Approach 1:
The spatial filter is designed to perform multiple functions simultaneously: it acts as a spectral filter, a spatial frequency selector, and a coherence control element all in one component. By positioning the spatial filter in the Fourier plane and configuring it with multiple transmission regions, a single device achieves what would otherwise require multiple separate optical systems, thereby managing complexity while enabling multi-field display.
3Manufacturing precision
If larger portions of the Fourier transform are allocated to image fields with greatest perceptual significance, then perceived image quality improves, but the number of image fields that can be displayed simultaneously decreases
Solution Approach 1:
Different portions of the spatial-frequency domain are allocated different sizes based on the perceptual importance of the corresponding image fields. Image fields with greatest perceptual significance are assigned larger regions in the Fourier plane, allowing them to occupy more spatial frequency bandwidth and achieve higher perceived quality. Less important fields are assigned smaller regions, optimizing the overall system productivity while maintaining quality where it matters most.
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 enables a significant increase in the number of image fields displayed per unit time, improving motion smoothness and reducing color breakup in holographic displays, while allowing for higher effective resolution and eyebox expansion.
Implementation Method 1
a spatial filter positioned substantially in the Fourier plane of the SLM, the spatial filter comprising a plurality of regions, each region corresponding to a portion of F(H) representing an image field, and each region configured to pass light relating to the image field corresponding to that region
Implementation Method 2
information relating to each image field of the plurality of image fields occupying a different portion of the Fourier Transform of H, F(H)
Data Source
AI summary
A display system comprises: an illumination system configured to emit at least partially coherent light; a spatial light modulator, SLM, illuminated by the illumination system and for applying a modulation pattern to illuminating light, the SLM configured to form a single modulation pattern, H, simultaneously representing a plurality of image fields, information relating to each image field of the plurality of image fields occupying a different portion of the Fourier Transform of H, F(H); an optical system arranged to receive the light modulated by the SLM and to produce a Fourier plane of the SLM; and a spatial filter positioned substantially in the Fourier plane of the SLM, the spatial filter comprising a plurality of regions, each region corresponding to a portion of F(H) representing an image field, and each region configured to pass light relating to the image field corresponding to that region. In some examples, in the single modulation pattern, information relating to an image field having greatest perceptual significance to a viewer occupies a largest portion of F(H).