Wavefront Corrective Element for Shack-Hartmann Sensor Dynamic Range
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Solution Overview
Problem
Shack-Hartmann wavefront sensors face limitations in measuring highly aberrated wavefronts due to dynamic range constraints, leading to difficulties in accurately analyzing wavefronts with significant deviations, which can result in overlapping focal spots and reduced measurement accuracy.
Innovation Solution
Incorporating a wavefront corrective element, such as a negative plano-concave lens, between the test element and the lenslet array to partially correct aberrations, allowing for estimation of wavefront parameters within the dynamic range of the sensor, and utilizing maximum likelihood estimation with a contracting-grid search algorithm for optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Shack-Hartmann wavefront sensor is used to measure highly aberrated wavefronts, then the dynamic range of the sensor is exceeded, but this leads to overlapping focal spots and reduced measurement accuracy
Solution Approach 1:
The patent applies preliminary action by introducing a wavefront corrective element (such as a negative plano-concave lens) between the test element and the lenslet array to pre-correct aberrations before they reach the sensor. This preliminary correction ensures that the wavefront parameters remain within the dynamic range of the sensor, preventing focal spot overlapping and maintaining measurement accuracy across various aberration levels.
Solution Approach 2:
The wavefront corrective element serves as an intermediary component in the optical path. It mediates between the highly aberrated wavefront from the test element and the sensor's limited dynamic range, transforming the wavefront to a state that the sensor can accurately measure without saturation or focal spot overlap.
2Measurement precision
If wavefront corrective element is introduced to reduce aberrations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by using a wavefront corrective element with specific optical parameters (such as a negative plano-concave lens with calculated focal length and curvature) to target and correct specific aberration modes. By carefully selecting and optimizing these parameters, the system achieves improved measurement precision while keeping the added complexity manageable through targeted rather than comprehensive correction.
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 enables faster and more accurate estimation of wavefront parameters by reducing aberrations within the sensor's dynamic range, improving measurement precision and reducing computational time for high-aberration wavefronts.
Implementation Method 1
a wavefront corrective element disposed between the lenslet array and the light source... configured to at least partially correct aberration of the wavefront
Data Source
AI summary
An apparatus for estimating a wavefront parameter includes a light source, a lenslet array, a detector for detecting light generated by the light source and passed through the lenslet array, a wavefront corrective element disposed between the lenslet array and the light source; and a data analyzer configured to estimate at least one wavefront parameter at a plane located on the light source side of the corrective element. The lenslet array and the sensor array are arranged to form a wavefront sensor, and the wavefront corrective element is configured to correct an aberration of the wavefront.