Complex Hologram Depth Mapping via Split-Lohmann All-in-Focus Images
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Solution Overview
Problem
Existing methods for estimating depth maps from holograms face challenges such as difficulty in determining object thickness using phase information alone, limitations in structured light emission range, high power consumption, and potential location exposure in military applications, as well as difficulties in extracting depth maps from holographic images with non-Gaussian blur kernels.
Innovation Solution
A device and method that utilize a processor to generate and update depth maps by minimizing the difference between all-in-focus images from complex holograms using a Split-Lohmann optical system, applying algorithms like Fresnel diffraction and hologram generation techniques to estimate an optimal depth map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-unwrapping technique is used to determine object thickness from complex hologram, then depth information can be extracted, but it becomes difficult to determine thickness when object becomes thicker or optical information space is recorded at everyday life scale
Solution Approach 1:
The patent introduces an all-in-focus image as an intermediary representation that bridges the complex hologram and the depth map. Instead of directly interpreting phase information which fails for thick objects, the system generates an all-in-focus image that preserves depth information in a format suitable for both thin and thick objects, enabling universal depth measurement across different object thicknesses and scales
2Ease of manufacture
If self-interference holography system with general light source is used to record 3D spatial light information, then hologram can be recorded, but phase change of object in accordance with depth becomes uniform making depth estimation difficult
Solution Approach 1:
The patent replaces the traditional optical depth estimation method (relying on phase changes) with an image processing approach using all-in-focus images. Instead of analyzing phase information which becomes uniform in self-interference holography, the system uses image sharpness and focus characteristics to extract depth information, effectively substituting optical measurement with computational imaging methods
3Measurement precision
If depth sensor such as ToF sensor or lidar is used to emit structured light for depth measurement, then depth information can be obtained, but it is limited in terms of structured light emission range and requires high power in presence of sunlight
Solution Approach 1:
The patent creates a computational copy of the holographic image data that contains encoded depth information. Instead of using physical structured light emission which has range and power limitations, the system digitally reconstructs depth information from the hologram through all-in-focus image generation, eliminating the need for additional active light emission and reducing power consumption while maintaining measurement capability
4Measurement precision
If depth sensor emitting structured light is used for military security purposes, then depth information can be obtained, but it may lead to location exposure
Solution Approach 1:
The patent substitutes active structured light emission with passive holographic recording and computational processing. By using existing light fields and generating depth information through image processing rather than active emission, the system eliminates the location exposure risk associated with transmitting structured light while maintaining depth measurement capability for security applications
5Measurement precision
If depth-from-defocus technique is applied to holographic images, then depth information can be extracted, but it is difficult to extract depth map without changes because blur kernel has diffraction characteristics differing from Gaussian profile
Solution Approach 1:
The patent changes the fundamental parameter used for depth extraction from defocus blur analysis to all-in-focus image generation. Instead of relying on Gaussian-like blur kernels that assume simple optical defocus, the system uses the specific diffraction characteristics of holographic images to generate all-in-focus images that preserve depth information, adapting the approach to the unique optical properties of holography
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
Improves the accuracy and efficiency of depth map estimation by optimizing the depth map to minimize image differences, enhancing picture quality and reducing power consumption in noncoherent hologram recording systems.
Implementation Method 1
generates a second all-in-focus image from the complex hologram using a hologram generation technique for generating a hologram by numerically applying a Split-Lohmann optical system
Implementation Method 2
Holography is a technology for recording the amplitude and phase information of light waves passing through a specific plane in a three-dimensional (3D) space
Implementation Method 3
a hologram is typically recorded using a phase-shifting interferometer to record a complex hologram containing light amplitude and phase information
Implementation Method 4
The processor may calculate a phase ramp using the depth map, calculate a phase ramp image using the phase ramp
Implementation Method 5
generates a first all-in-focus image from a complex hologram using an all-in-focus image conversion algorithm
Data Source
AI summary
Provided are a device and method for estimating a depth map using a complex hologram. The device includes a processor and a memory configured to store instructions executed by the processor. The processor generates a first all-in-focus image from a complex hologram using an all-in-focus image conversion algorithm, generates a second all-in-focus image from the complex hologram using a hologram generation technique for generating a hologram by numerically applying a Split-Lohmann optical system, and estimates a depth map in accordance with the first all-in-focus image and the second all-in-focus image.