Optical Focus Detection via Shack-Hartmann Wavefront Sensing
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Solution Overview
Problem
Current optical systems, particularly in material processing and ophthalmological applications like fs-LASIK, face challenges in precisely determining and controlling the focal position, which is crucial for high-precision material processing and accurate treatment.
Innovation Solution
A device and method that utilize a radiation source, a focusing imaging system, a partially reflecting surface, a digital sensor system, and an optical element in the beam path to precisely determine and adjust the focal position by recording and evaluating images reflected from the surface, allowing for precise alignment and adjustment of the focus in relation to a predetermined plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a diffractive optical element is used to increase numerical aperture, then the aperture is enlarged, but the manufacturing precision and complexity increase
Solution Approach 1:
The patent introduces a Shack-Hartmann sensor as an intermediary device that measures wavefront aberrations caused by high numerical aperture lenses. This sensor enables the system to detect and compensate for optical distortions, allowing the use of larger apertures without proportionally increasing system complexity. The sensor acts as a mediator between the high-NA lens and the detection system, providing feedback for correction.
Solution Approach 2:
The patent employs adaptive optics technology that dynamically adjusts optical parameters (wavefront shape) in real-time. By changing the wavefront parameters through deformable mirrors or liquid crystal modulators, the system compensates for aberrations introduced by high numerical aperture lenses, enabling large aperture operation without permanent increases in manufacturing complexity.
2Manufacturing precision
If focus position is not precisely controlled, then material processing precision deteriorates, but implementing focus detection increases device complexity
Solution Approach 1:
The patent implements a feedback mechanism where the Shack-Hartmann sensor continuously monitors wavefront aberrations and provides real-time data about focus position and quality. This feedback loop enables automatic adjustment of the optical system to maintain optimal focus, achieving high manufacturing precision without requiring complex manual intervention or overly complicated detection systems.
Solution Approach 2:
The optical system performs self-diagnosis and self-correction through the integrated wavefront sensor. The system automatically detects focus deviations and aberrations, then uses adaptive optics elements to correct them without external intervention. This self-service capability achieves high precision while minimizing the complexity of external control systems.
3Reliability
If wavefront aberrations are not corrected, then focus quality deteriorates, but implementing adaptive wavefront control increases device complexity and cost
Solution Approach 1:
The Shack-Hartmann sensor provides continuous feedback on wavefront aberrations, enabling real-time detection and correction. This feedback mechanism allows the system to maintain high focus quality by automatically compensating for aberrations, rather than requiring complex preventive measures or manual adjustments.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with wavefront sensing and computational correction. Instead of using multiple movable mechanical components to achieve perfect focus, the system uses a sensor to measure aberrations and applies computational optics or simple adaptive elements to correct them, reducing mechanical complexity while improving reliability.
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
Enables accurate positioning of the focal point, ensuring optimal focusing and precise material processing by allowing for adjustments in focus depth and orientation, enhancing the precision and effectiveness of material processing and ophthalmological treatments.
Implementation Method 1
The diffractive structure also consists of a segment-like arrangement of any binary or multi-stage diffractive elements. The arrangement can in particular be a hexagonal or hexagonal arrangement. In this way, an image of a light beam is achieved.
Data Source
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AI summary
Disclosed are an apparatus and a method for detecting the focused position of an optical system (10) comprising a radiation source (12), a focusing imaging system (16), an at least partially reflective surface (18) on the focus (18a), a digital camera (24) for recording an image that is reflected by said surface (18), a computer (C) for evaluating the image recorded by the camera (24), and an optical element (34; 36) in the beam path of the optical system (10) upstream of the focusing imaging system (16), said optical element (34; 36) influencing the image in accordance with the focused position.