Shack-Hartmann Sensor Wavefront Precision via Spot Segmentation
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Solution Overview
Problem
Shack-Hartmann sensors face a drop in wavefront measuring precision due to steep local wavefront slopes and large slope variations, leading to reduced center-of-gravity position detecting precision and increased crosstalk in large wavefront aberration measurements.
Innovation Solution
A wavefront measuring method using a Shack-Hartmann sensor with a micro lens array and light receiving elements, where the center-of-gravity position is provisionally determined, and areas are set to calculate the distance between adjacent positions, reducing overlap and enabling precise wavefront calculation by adjusting the detection area based on the distance between center-of-gravity positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the Shack-Hartmann sensor measures large wavefront aberration with steep local wavefront slopes, then the dynamic range is enlarged, but the distance between CoG positions of spots reduces and measuring precision drops
Solution Approach 1:
The patent segments the spot detection process by dividing the detection area into multiple regions and calculating CoG positions for each region separately. This segmentation allows the system to maintain precision even when spots overlap by analyzing local intensity distributions in divided areas, thereby resolving the contradiction between enlarged dynamic range and maintained measuring precision.
Solution Approach 2:
The patent performs preliminary characterization of light transmission through each micro lens and establishes correlation between micro lenses and spots before measurement. This preliminary action creates a reference framework that enables accurate wavefront reconstruction even when spot positions shift significantly, allowing the system to handle large wavefront aberrations while maintaining precision.
2Adaptability or versatility
If the local wavefront slope is steep, then the wavefront aberration dynamic range increases, but the CoG position detecting precision lowers due to reduced distance between spots
Solution Approach 1:
The patent applies local quality by analyzing intensity distributions in locally divided areas rather than treating each spot as a single entity. By examining the intensity profile within segmented regions and calculating CoG positions for each segment, the system maintains detecting precision even when spots overlap due to steep wavefront slopes, thus resolving the contradiction between extended measurement capability and preserved precision.
3Adaptability or versatility
If the distance between CoG positions of spots reduces, then the dynamic range is enlarged, but crosstalk increases and measuring precision drops
Solution Approach 1:
The patent segments the intensity distribution analysis into multiple local areas, calculating CoG positions for each segment rather than treating overlapping spots as a single entity. This segmentation approach isolates the contribution of each micro lens to specific regions, reducing crosstalk between adjacent spots and maintaining measurement reliability even when the distance between CoG positions is reduced to expand dynamic range.
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 method maintains wavefront measuring precision by reducing crosstalk and dynamic range issues, allowing for accurate wavefront calculations even in cases of steep slope variations.
Implementation Method 1
a plurality of micro lenses configured to condense light that has passed the target optical system upon the light receiving elements
Implementation Method 2
the 'spot' has an intensity distribution of light that is condensed on the light receiving sensor by each micro lens. A center-of-gravity ('CoG') position of the spot shifts due to a wavefront slope incident upon the micro lens array when the light is condensed
Data Source
AI summary
A wavefront measuring method using a Shack-Hartmann sensor includes the steps of provisionally determining one of a plurality of light receiving elements as a center-of-gravity position in a spot having a light intensity distribution of light condensed on the light receiving element, calculating a distance between the provisionally determined center-of-gravity position and an adjacent center-of-gravity position, setting an area smaller than and inside of a spot that partially overlaps another spot, and setting a spot that does not overlap another spot to the area, calculating a center-of-gravity position for each area, and calculating the wavefront based upon a shift amount between an ideal center-of-gravity position when parallel light enters the micro lens array and the center-of-gravity position of each area.