CMOS Wavefront Sensor With Integrated Binary Lens to Reduce Crosstalk
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Solution Overview
Problem
Conventional wavefront sensors, such as Shack-Hartmann Sensors, face challenges with crosstalk due to large spot displacements, which can result in beam absorption by neighboring pixels, limiting their accuracy in measuring distorted wavefronts.
Innovation Solution
A CMOS wavefront sensor with a binary lens integrated in the passivation layer, using a pattern of alternating refractive index materials to focus incident light onto an array of photodiodes, reducing the distance between the lens and photodiodes to minimize crosstalk and allowing precise determination of light angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Shack-Hartmann sensor uses a microlens array to focus light onto a detector, then wavefront shape can be analyzed through spot displacement, but large spot displacements cause crosstalk where beams are absorbed by neighboring pixels
Solution Approach 1:
The patent integrates the microlens array directly with the photodetector array to form a single combined component. This merging eliminates the separation between lens and detector that causes spot displacement and crosstalk, while maintaining the wavefront sensing capability through direct optical coupling.
Solution Approach 2:
The patent transitions from a planar microlens array to a three-dimensional stacked architecture where microlenses are positioned above photodetectors in the vertical dimension. This vertical stacking allows light to be focused directly onto the intended photodetector without lateral displacement, eliminating crosstalk while preserving measurement accuracy.
2Ease of operation
If conventional wavefront sensors use separate microlens arrays and detectors, then wavefront analysis is possible, but the distance between lens and photodiodes increases causing beam absorption by neighboring pixels
Solution Approach 1:
The patent combines the microlens array and photodetector array into a single integrated component where each microlens is directly coupled to its corresponding photodetector. This integration maintains full wavefront sensing capability while eliminating the spatial separation that causes crosstalk and improves measurement reliability.
Solution Approach 2:
The integrated microlens-photodetector structure serves multiple functions simultaneously: it focuses incident light, directs it to the correct photodetector, and prevents crosstalk all within a single unified component, improving both ease of operation and reliability.
3Measurement precision
If large spot displacements occur in Shack-Hartmann sensors, then distorted wavefronts can be detected, but neighboring pixels absorb the beam causing measurement errors
Solution Approach 1:
The patent uses vertical stacking to separate the optical focusing function from the detection function in the vertical dimension, allowing distorted wavefronts to be detected through focal point shifts along the optical axis rather than lateral spot displacements, thereby preventing beam absorption by neighboring pixels.
Solution Approach 2:
By merging the microlens and photodetector into a single integrated unit, the patent ensures that even when wavefront distortions occur, the focused light remains confined to the intended photodetector, preventing information loss due to crosstalk while maintaining detection capability.
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 CMOS wavefront sensor effectively reduces crosstalk and enhances accuracy in determining wavefront angles, enabling precise measurement of distorted light beams without the need for separate microlens arrays, and is adaptable across various wavelength spectra.
Implementation Method 1
a binary lens formed in the passivation layer and arranged to focus incident light onto the sensor element
Data Source
AI summary
A Complementary Metal Oxide Semiconductor (CMOS) wavefront sensor including a sensor element having an array of photodiodes and a passivation layer covering the sensor element. The sensor further includes a binary lens formed in the passivation layer and arranged to focus incident light onto the sensor element.