Spatial Light Modulator Optical Pattern Formation Reduces Zero-Order Noise
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Solution Overview
Problem
Existing optical pattern formation technologies using phase-modulating spatial light modulators suffer from the issue of 0-order light noise, which degrades the shape of optical patterns when they are located near or overlap with the target pattern, limiting the flexibility in pattern design and application.
Innovation Solution
The method involves generating and modulating reading light using a phase-modulating spatial light modulator, followed by Fourier-transforming and focusing the light to blur the 0-order light on a separate plane, using a lens with a focal plane and optical axis, and employing phase patterns with lens effects, such as Fresnel zone patterns, to displace the output plane and reduce 0-order light luminance without blocking the target pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield plate is placed on the optical path to block the 0-order light, then the 0-order light is reduced, but the shape of the optical pattern is blocked and degraded
Solution Approach 1:
The patent extracts and removes only the harmful 0-order light component from the optical path using a spatial light modulator, while preserving the desired optical pattern. The SLM selectively modulates the phase of the 0-order light to redirect it away from the output plane, separating the harmful component from the useful pattern without blocking the entire beam path.
Solution Approach 2:
The patent applies local quality by selectively treating different spatial frequency components of the light. The spatial light modulator applies different phase modulation to the 0-order component versus the pattern-carrying components, allowing differential control where the 0-order light is redirected while the pattern information is preserved at the output plane.
2Object-affected harmful factors
If an insensitive portion is provided at the position where the 0-order light is incident, then the 0-order light is blocked, but the optical pattern is also blocked and shape is degraded
Solution Approach 1:
The spatial light modulator acts as an intermediary device that mediates between the incoming light containing 0-order noise and the desired optical pattern. It dynamically modulates the phase of light components based on their spatial frequency characteristics, allowing the system to filter 0-order light while preserving pattern information through controlled phase manipulation rather than physical blocking.
3Measurement precision
If the output plane is placed at the focal plane of the lens, then the optical pattern is focused sharply, but the 0-order light also appears clearly as noise
Solution Approach 1:
The patent resolves the contradiction by operating in the spatial frequency domain rather than directly in real space. The spatial light modulator processes light in the Fourier domain, applying phase modulation to specific spatial frequency components (the 0-order component) before they are transformed back to real space at the output plane. This dimensional transformation in optical processing space allows selective manipulation of the 0-order light without affecting the pattern.
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 effectively reduces 0-order light noise on the output plane, allowing for unrestricted shape design of optical patterns and preventing pattern degradation, enabling precise control and flexibility in applications like laser processing and optical tweezers.
Implementation Method 1
modulating the phase of the reading light using a phase-modulating spatial light modulator
Implementation Method 2
Fourier-transforming the modulated reading light and focusing an image of the Fourier-transformed reading light on an output plane
Implementation Method 3
focusing an image of the Fourier-transformed reading light on an output plane
Implementation Method 4
producing the phase pattern by adding a subsidiary phase pattern with lens effect to a principal phase pattern
Implementation Method 5
This subsidiary phase pattern may be a Fresnel zone pattern
Data Source
AI summary
Reading light (26) is phase-modulated by a phase-modulating spatial light modulator (12), the phase-modulated reading light (26) is Fourier-transformed, and an image of the Fourier-transformed reading light is focused on an output plane (24) to form an optical pattern. In this method, 0-order light in the phase-modulated reading light (26) is blurred on the output plane (24). As the 0-order light is blurred, the luminance of the 0-order light is reduced on the output plane (24). Since the 0-order light is not blocked, the shape of the optical pattern is not limited.