Holographic Wavefront Printing Using Inclined Phase SLM and Blazed Grating
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Solution Overview
Problem
The practical application of phase spatial light modulators in holographic wavefront printing is limited due to the discrete characteristics of their pixelated structure, which cause adverse effects from dead region diffracted light and active region high-order diffracted light.
Innovation Solution
A holographic wavefront printing system that incorporates a phase spatial light modulator with a two-dimensional digital blazed grating and an inclined phase spatial light modulator, along with a low-pass filter, to adjust the emergent direction of active region diffracted light and prevent overlapping frequency spectra, thereby suppressing the adverse effects of dead region and high-order diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a phase spatial light modulator with pixelated structure is used, then high spatial bandwidth product and energy utilization are achieved, but dead region diffracted light and active region high-order diffracted light interfere with the printing process
Solution Approach 1:
The patent extracts and removes the harmful diffracted light components (dead region diffracted light and active region high-order diffracted light) from the optical path using optical filters, allowing only the useful zeroth-order diffracted light to pass through to the holographic recording material
Solution Approach 2:
The patent introduces optical filters as intermediary elements between the phase spatial light modulator and the holographic recording material to selectively transmit useful light while blocking harmful diffracted light, thereby resolving the interference problem
2Reliability
If a phase spatial light modulator is used to avoid conjugate image interference, then single reconstructed image quality is improved, but discrete characteristics cause multi-order diffracted light interference
Solution Approach 1:
The patent extracts and removes the harmful multi-order diffracted light components from the optical path using optical filters, allowing only the useful zeroth-order diffracted light to pass through to the holographic recording material
Solution Approach 2:
The patent introduces optical filters as intermediary elements between the phase spatial light modulator and the holographic recording material to selectively transmit useful light while blocking harmful diffracted light
3Reliability
If amplitude spatial light modulator is used, then conjugate image and original object image are generated simultaneously, but filtering is required to remove conjugate image influence
Solution Approach 1:
The patent uses a phase spatial light modulator that creates a digital copy of the hologram information through phase modulation, eliminating the need for physical filtering to remove conjugate images, as phase modulation produces only the desired reconstructed image without unwanted conjugate components
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 solution effectively suppresses the discrete characteristics of the phase spatial light modulator, improving the printing quality and reliability of holographic wavefront printing by ensuring high spatial bandwidth and energy utilization, enabling the production of large-format, white-light reproducible volume holograms and functional HOEs.
Implementation Method 1
The active region is configured to load the phase hologram to modulate the phase of the incident light, thereby generating the active region diffracted light containing the phase information of the object
Implementation Method 2
The diffracted light is incident on the first lens and emitted onto the back focusing surface of the first lens after being subjected to an optical Fourier transform of the first lens
Implementation Method 3
The low-pass filter is placed on the back focusing surface of the first lens, and configured to filter the dead region diffracted light and the active region high-order diffracted light
Implementation Method 4
The object light containing the effective information of the phase hologram and the reference light are incident onto the holographic recording material, interference is generated in the holographic recording material, and a volume hologram is generated
Data Source
AI summary
A holographic wavefront printing system and method are provided. A two-dimension digital blazed grating is loaded on a phase hologram, and the emergent direction of active region diffracted light is adjusted to prevent overlapping with the dead region diffracted light after being Fourier transformed by a lens, and a phase spatial light modulator is inclined by a preset angle to change the emergent direction of the diffracted light, such that the dead region zeroth-order and first-order diffracted light on a focusing surface are symmetrical with respect to a main optical axis of a first lens, the frequency spectrum center of active region zeroth-order diffracted light is then loaded to the original frequency spectrum center without information change. In this way, the adverse effects of the dead region diffracted light and active region high-order diffracted light of the phase spatial light modulator on holographic wavefront printing are eliminated.