Phase Diversity Wavefront Sensor for Large Aberrations
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Solution Overview
Problem
Conventional wavefront sensors, such as Shack Hartmann wavefront sensors, face challenges in measuring wavefronts with discontinuities and limited dynamic range, particularly in ophthalmic applications involving multifocal lenses and large aberrations, which complicates the measurement of wavefronts produced by multifocal optical elements like diffractive intraocular lenses.
Innovation Solution
A phase diversity wavefront sensor system incorporating a diffractive optical element with a filter function, capable of producing images associated with multiple diffraction orders, and a detector for telecentric pupil plane imaging, along with a Gerchberg-Saxton phase retrieval algorithm to accurately measure wavefronts with speckle and large aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Shack Hartmann wavefront sensor is used to measure wavefronts, then the measurement process is simple, but it cannot accurately measure wavefronts with discontinuities or multiple tilts
Solution Approach 1:
The wavefront measurement is divided into multiple discrete planes (first plane and second plane) along the propagation direction. By segmenting the measurement into multiple axial positions, the system can capture wavefront information at different depths, enabling accurate measurement of wavefronts with discontinuities and multiple tilts that a single-plane sensor cannot resolve.
Solution Approach 2:
The invention transitions from two-dimensional wavefront measurement (single transverse plane) to three-dimensional measurement by introducing the axial dimension (propagation direction). Multiple measurement planes spaced along the propagation direction provide depth information, allowing the system to distinguish between wavefront features at different axial positions and accurately measure discontinuous or multifocal wavefronts.
2Adaptability or versatility
If an adjustable optical system is employed to maintain the Shack Hartmann sensor within its dynamic range, then the measurement range is extended, but the system complexity and alignment requirements increase
Solution Approach 1:
Instead of using mechanically adjustable optical elements to adapt the system to different wavefront conditions, the invention employs a fixed multi-plane measurement configuration. The multiple measurement planes are statically positioned along the propagation direction, allowing the system to dynamically capture a wide range of wavefront aberrations without requiring mechanical adjustment or complex alignment procedures.
Solution Approach 2:
The multi-plane wavefront sensor simultaneously performs multiple measurement functions across different axial positions, making the system universally applicable to various wavefront conditions (small and large aberrations, continuous and discontinuous wavefronts) without requiring separate adjustment mechanisms for each measurement scenario.
3Ease of operation
If conventional wavefront sensors are used for ophthalmic applications with large aberrations, then the measurement process is straightforward, but the dynamic range is limited
Solution Approach 1:
The measurement process is segmented into multiple discrete planes along the propagation direction, with each plane capturing wavefront information within its own dynamic range. By combining data from multiple planes, the system achieves an extended overall dynamic range that can accommodate large ophthalmic aberrations while maintaining operational simplicity at each individual measurement plane.
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 system effectively measures wavefronts with multiple tilts and large aberrations, providing a wider dynamic range without the need for adjustable optical elements, simplifying the measurement process and improving precision in ophthalmic applications.
Implementation Method 1
a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders
Data Source
AI summary
A phase diversity wavefront sensor includes an optical system including at least one optical element for receiving a light beam; a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images. In one embodiment, the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam. A processor receives the image data from the detector, and executes a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.