Beam Expander Using Spatial Light Modulators for Rapid Diameter Adjustment
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Solution Overview
Problem
Conventional beam expanders require complex mechanical mechanisms to change light diameter, leading to low positional accuracy and long setup times due to the need for moving lens groups along the optical axis.
Innovation Solution
A beam expander comprising a first lens unit and a second lens unit, each comprising a spatial light modulator or a vari-focal lens, with a control unit that adjusts their focal lengths to change the light diameter without moving the lens groups, allowing for rapid and precise adjustments in a fixed optical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lens groups are mechanically moved to change light diameter, then light diameter can be adjusted, but device complexity increases and adjustment time increases
Solution Approach 1:
The patent replaces the mechanical lens group movement system with an optical field modulation system using spatial light modulators (SLM). Instead of physically moving lens groups along the optical axis, the SLM modulates the optical field to achieve beam expansion and compression. This substitution eliminates complex mechanical mechanisms while maintaining light diameter adjustment capability through electrical control of the SLM pixels.
Solution Approach 2:
The patent changes the focal lengths of the lens units by modulating the optical field parameters through the spatial light modulator. By controlling the phase or amplitude distribution of light across the SLM pixels, the effective focal length of each lens unit can be dynamically adjusted without mechanical movement. This parameter-based control enables light diameter adjustment while keeping the physical distance between lens units fixed.
2Adaptability or versatility
If lens groups are mechanically moved to change light diameter, then light diameter can be adjusted, but adjustment time increases
Solution Approach 1:
The patent replaces slow mechanical lens group movement with rapid electrical control of the spatial light modulator. The SLM can change its pixel states almost instantaneously in response to electrical signals, enabling quick adjustment of light diameter without the inertia and mechanical delays inherent in moving lens groups. This electrical-optical control pathway dramatically reduces adjustment time while maintaining full adaptability.
Solution Approach 2:
The patent introduces dynamic control of the optical system through the spatial light modulator, which can rapidly change its modulation pattern in response to control signals. This dynamic capability allows the system to adapt light diameter quickly without mechanical movement, transforming a static mechanical adjustment process into a dynamic electrical control process that operates on much faster timescales.
3Measurement precision
If lens groups are mechanically moved to improve positional accuracy, then positional accuracy improves, but device complexity increases
Solution Approach 1:
The patent replaces mechanical lens positioning with optical field modulation through the spatial light modulator. Positional accuracy is achieved not through precise mechanical placement of lens groups, but through precise electrical control of the SLM pixel states. The SLM can be controlled with high precision via digital signals, eliminating the need for complex mechanical positioning mechanisms while achieving superior positional accuracy in beam expansion/compression.
Solution Approach 2:
The patent creates an optical field copy or representation of the desired beam profile through the spatial light modulator. Instead of physically positioning lens groups to achieve the correct optical path, the SLM generates the appropriate phase or amplitude distribution that replicates the effect of perfectly positioned lens groups. This optical copying approach achieves high positional accuracy without mechanical complexity.
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
Enables easy configuration and rapid changes in light diameter, reducing setup time and eliminating the need for complex mechanical mechanisms, while maintaining high accuracy and efficiency.
Implementation Method 1
a first lens unit which includes one of a spatial light modulator or a van-focal lens... a control unit that controls focal lengths of the first lens unit and the second lens unit... the control unit controls the focal lengths of the first lens unit and the second lens unit by providing a lens pattern to a spatial light modulator, or by controlling a focal length of a van-focal lens
Data Source
AI summary
A beam expander includes a first lens unit including one of an SLM or a VFL, a second lens unit being optically coupled to the first lens unit and including one of an SLM or a VFL, and a control unit controlling focal lengths of the first and second lens units. A distance between the first and second lens units is invariable. The control unit controls the focal lengths of the first and second lens units such that a light diameter D1 of light input to the first lens unit and a light diameter D2 of light output from the second lens unit are different from each other.