Holographic Projector Calibration Using Phase-Ramp Boundary Alignment
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Solution Overview
Problem
Current methods for calibrating holographic projectors are inefficient in correcting rotational misalignments, requiring manual adjustments and expensive equipment, which are time-consuming and can degrade the quality of both picture and non-picture areas of the holographic reconstruction.
Innovation Solution
A method using a phase-ramp function to translate the boundary between the picture and non-picture areas into view, allowing for software-based calibration by measuring the angle of this boundary to correct rotational misalignments without physical adjustments, thus enabling faster and more cost-effective alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustments and expensive equipment are used to correct rotational misalignments, then alignment precision is improved, but manufacturing time and costs increase
Solution Approach 1:
The patent replaces manual mechanical adjustment methods with an automated software-based calibration system. The system uses a camera to capture images of the holographic reconstruction, processes these images through software algorithms to detect rotational misalignment, and automatically calculates correction parameters. This substitution of mechanical manual operations with automated optical-digital systems resolves the contradiction by achieving high alignment precision through software processing rather than time-consuming manual adjustments.
Solution Approach 2:
The patent creates a digital copy (image) of the holographic reconstruction using a camera, and then performs calibration operations on this copy rather than directly manipulating the physical system. By working with the captured image data, the system can measure rotational misalignment and compute corrections without physically disturbing the setup, thereby maintaining precision while significantly reducing calibration time and eliminating the need for expensive manual adjustment equipment.
2Manufacturing precision
If manual adjustments are used to correct rotational misalignments, then alignment accuracy is improved, but device complexity and costs increase
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with a simpler optical-digital system consisting of a camera, image processing software, and automated calculation algorithms. This substitution reduces device complexity by eliminating mechanical adjustment components while maintaining or improving alignment accuracy through software-based measurement and correction.
Solution Approach 2:
The calibration system is designed to be self-calibrating through automated image capture, processing, and correction parameter calculation. The system performs its own calibration without requiring external manual intervention or complex adjustment mechanisms, thereby reducing device complexity while achieving high alignment accuracy through self-service automation.
3Productivity
If software-based calibration is used to correct rotational misalignments, then productivity is improved, but measurement precision may be compromised
Solution Approach 1:
The patent captures a digital copy (image) of the holographic reconstruction and performs all measurement operations on this copy. The software analyzes the captured image to detect the boundary between picture and non-picture areas, measures rotational misalignment, and calculates correction parameters. This approach enables high-speed automated processing while maintaining measurement precision through sophisticated image analysis algorithms that can accurately identify boundaries and compute angles from the digital image data.
Solution Approach 2:
The patent replaces manual measurement methods with automated image-based measurement. The software processes captured images to determine boundary positions and rotational angles, substituting human measurement operations with automated digital processing. This substitution increases calibration speed (productivity) while maintaining or improving measurement precision through consistent, repeatable algorithmic analysis of the captured images.
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
The method effectively corrects rotational misalignments of holographic projectors by software, reducing manufacturing time and costs, while maintaining the quality of both picture and non-picture areas, and can be performed at any time, including post-manufacturing.
Implementation Method 1
Some embodiments of the method relate to the use of a phase-ramp function to translate the holographic reconstruction to bring a boundary between a picture area and a non-picture area of the holographic reconstruction into view
Implementation Method 2
Light modulation may be achieved using electrically-addressable liquid crystals, optically-addressable liquid crystals or micro-mirrors, for example
Implementation Method 3
The holographic reconstruction may be formed by illuminating a diffractive structure displayed on the display device using the light source and using the one or more optical components
Data Source
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AI summary
There is provided a method of calibrating a holographic projector. The method comprises displaying a primary diffractive pattern on a display device, wherein the primary diffractive pattern comprises a first hologram of a first target image and a phase-ramp function. The method further comprises illuminating the primary diffractive pattern to form a first holographic reconstruction of the first target image on a replay plane. The first target image comprises a picture area and a non-picture area. The phase-ramp function is arranged to translate the first holographic reconstruction. The method further comprises blocking at least a portion of the first holographic reconstruction using a mask, wherein the mask is arranged to block the non-picture area in the absence of the phase-ramp function. The method further comprises measuring a property of a boundary between the picture area and the non-picture area. There is further provided a holographic projection system.