Cylindrical Lens Alignment via Optical Imaging
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Solution Overview
Problem
High-precision optical systems that incorporate cylindrical lenses face challenges in achieving tight rotational alignment due to the non-rotationally symmetric optical power of cylindrical lenses, leading to significant performance issues when standard contact-based measurement techniques are insufficient for tight tolerances like 5 milliradians or less.
Innovation Solution
A method involving an adjustable lens fixture that captures line images formed by the cylindrical lens in both forward and backward orientations, determining angular misalignment, and rotating the lens to achieve alignment within specified tolerances, utilizing a non-contact, self-referencing approach that relies on the refractive properties of the lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard contact-based measurement techniques are used to measure cylindrical lens orientation, then the measurement process is simple and direct, but the measurement precision is insufficient for tight tolerances (5 milliradians or less)
Solution Approach 1:
The patent replaces mechanical contact-based measurement with an optical measurement system. A camera captures images of the cylindrical lens, and image processing algorithms determine the lens orientation. This substitution of mechanical systems with optical and computational methods enables measurement precision better than 1 milliradian, far exceeding the capability of standard mechanical probing techniques.
Solution Approach 2:
The patent creates an optical copy (image) of the cylindrical lens using a camera, and then analyzes this copy to determine the lens orientation. Instead of directly measuring the physical lens with mechanical contact, the system captures an image and processes it computationally. This copying approach allows for non-contact, high-precision measurement that preserves the lens surface while achieving the required alignment accuracy.
2Reliability
If tight rotational alignment tolerance (1-5 milliradians) is required for cylindrical lens, then optical performance is improved, but the difficulty of detecting and measuring alignment increases
Solution Approach 1:
The patent replaces difficult mechanical alignment measurement with optical imaging and computational analysis. The camera-based system captures the cylindrical lens appearance, and image processing algorithms automatically calculate the lens orientation relative to the fixture. This approach makes tight tolerance measurement (1-5 milliradians) routine and reliable, rather than difficult and error-prone.
Solution Approach 2:
The measurement system uses the cylindrical lens's own optical properties and geometric features to perform self-measurement. The algorithm analyzes the lens's cylindrical shape and orientation features visible in the image to determine alignment. The lens essentially measures itself through its interaction with light, eliminating the need for external mechanical measurement tools that would be difficult to use at such tight tolerances.
3Adaptability or versatility
If cylindrical lens with minimal surface curvature is used, then design flexibility is increased, but the difficulty of detecting and measuring alignment increases further
Solution Approach 1:
The patent replaces mechanical measurement that struggles with minimal surface curvature with optical imaging. The camera captures the lens appearance, and image processing algorithms detect the cylindrical features and orientation even when the surface curvature is very subtle. This optical-computational approach is not limited by the lens curvature magnitude, allowing measurement of lenses with minimal surface curvature that would be nearly impossible to measure with mechanical contact methods.
4Ease of manufacture
If contact-based measurement is used to align cylindrical lens, then the alignment process is straightforward, but the risk of damaging optical surfaces increases
Solution Approach 1:
The patent replaces mechanical contact measurement with non-contact optical measurement. A camera images the cylindrical lens from a distance, and computational algorithms determine alignment without any physical contact. This eliminates the risk of scratching or damaging the optical surfaces that is inherent in mechanical probing methods, while still providing the alignment information needed for precise positioning.
Solution Approach 2:
The patent creates an optical copy (image) of the cylindrical lens for measurement purposes. Instead of physically touching the lens with measurement tools, the system captures an image and analyzes it computationally. This copying approach allows the alignment process to proceed without any mechanical contact, thereby protecting the optical surfaces from damage while maintaining alignment accuracy.
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 provides accurate alignment to better than 1 milliradian, reduces the risk of damaging optical surfaces, allows for looser angular orientation tolerances, and enables the use of cylindrical lenses with minimal surface curvature, thereby improving optical performance and reducing costs.
Implementation Method 1
Cylindrical lenses are refractive optical elements that have optical power in a first plane and no (or substantially less) optical power in a second plane orthogonal to the first plane
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
The method of aligning a cylindrical lens in a lens assembly includes attaching the cylindrical lens to a lens fixture and interfacing the lens fixture to a support structure in which the cylindrical lens can be placed in a frontwards and backwards orientation. method also includes capturing respective first and second line images of respective first and second focus lines as formed by the cylindrical lens in the forwards and backwards orientations. method further includes establishing a relative orientation of the first and second line images and using the established relative orientation to determine an amount of angular misalignment of the cylindrical lens relative to a reference direction provided by the support structure. method can include rotating the cylindrical lens relative to the lens fixture to reduce the amount of angular misalignment to be within an angular alignment tolerance.