Variable Transmission Filter Wavefront Sampling
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Solution Overview
Problem
Current wavefront sensing technologies, such as Shack-Hartmann Wavefront Sensors and pinhole aperture systems, face limitations in dynamic range and spatial sampling resolution, making them inadequate for applications requiring high sensitivity and large dynamic range, especially in adaptive optics and MEMS-based systems.
Innovation Solution
A discrete wavefront measurement device utilizing a variable transmission filter (VTF) decouples dynamic range from spatial sampling resolution and measurement sensitivity, allowing for configurable settings at a lower cost, by mapping local wavefront tilts to spatial displacements and using a pixilated detector to read optical intensities, with adaptive capabilities to change field of view and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Shack-Hartmann Wavefront Sensor uses lenslet array to increase dynamic range, then dynamic range is improved, but spatial sampling resolution is degraded
Solution Approach 1:
The patent extracts the dynamic range limitation from the lenslet array system by removing the lenslet array entirely and replacing it with a single lens combined with a variable transmission filter. This extraction allows the system to achieve large dynamic range without the spatial resolution degradation inherent in lenslet-based systems.
Solution Approach 2:
The patent changes the transmission parameter of the optical filter dynamically to adapt to different wavefront tilt ranges. By varying the filter's transmission characteristics rather than changing physical aperture sizes, the system achieves both high dynamic range and maintained spatial sampling resolution.
2Adaptability or versatility
If lenslet diameter is increased to improve dynamic range, then dynamic range is improved, but spatial sampling resolution is reduced
Solution Approach 1:
The patent removes the lenslet array component entirely, extracting the dynamic range function from the lenslet diameter parameter. This eliminates the direct trade-off between lenslet size and spatial resolution, as the system uses a different mechanism (variable transmission filter) to achieve dynamic range adjustment.
Solution Approach 2:
The patent replaces the mechanical lenslet array system with an optical system using a single lens and variable transmission filter. This substitution eliminates the need to physically adjust lenslet diameters, allowing dynamic range control without mechanical changes that would affect spatial sampling.
3Adaptability or versatility
If focal length is decreased to improve dynamic range, then dynamic range is improved, but measurement sensitivity is degraded
Solution Approach 1:
The patent changes the transmission parameter of the optical filter to control dynamic range rather than changing the focal length. This parameter change approach allows dynamic range adjustment without affecting the optical system's sensitivity, as the filter modification does not alter the focusing properties or signal strength.
4Measurement precision
If interferometric techniques are used to improve measurement sensitivity, then measurement sensitivity is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the wavefront sensing function from complex interferometric systems and implements it using a simplified single-lens-and-filter architecture. This extraction maintains measurement capability while eliminating the need for interferometers, CCD arrays, and complex analysis software.
Solution Approach 2:
The patent replaces expensive, complex interferometric equipment with simpler, more affordable optical components. The variable transmission filter and single lens system provides comparable measurement sensitivity at lower cost and reduced complexity, making wavefront sensing accessible without requiring sophisticated interferometric setups.
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 solution provides a cost-effective means to achieve high sensitivity and dynamic range, suitable for adaptive optics and MEMS-based applications, with increased fidelity in wavefront measurements and reduced complexity compared to traditional systems.
Implementation Method 1
an optical system having an effective numerical aperture (NA). The optical system maps the local tilt of each sub-region of the optical wavefront to a spatial displacement at the back focal plane of the system
Implementation Method 2
The VTF exhibits a variable transmission profile over an active region up to a cut-off angle imposed by the NA of the optical system, and the detector size, focal length, and the conjugate image plane distance from the back focal plane. The VTF attenuates the wavefront in accordance with the spatial displacements of each sub-region
Implementation Method 3
A pixilated detector positioned at the conjugate image plane is responsive to the attenuated wavefront to discretely read out optical intensities across the different sub-regions of the wavefront
Data Source
AI summary
A discrete wavefront measurement device uses a variable transmission filter (VTF) to decouple the dynamic range of tilt angle measurements in the wavefront from the spatial sampling resolution and the measurement sensitivity as regards the physics of the readout. This approach allows the discrete wavefront measurement device to be configured to a specified dynamic range, transverse sampling resolution and measurement sensitivity at low cost.