Inter-fitting Locating Grooves for Precision Lens Array Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods fail to precisely locate and form high-precision arrays of miniature optical lenses with consistent center-to-center spacings, particularly in telecommunications equipment and advanced optoelectronics, where maintaining 250 μm spacing with a positioning error of 2 μm is crucial.
Innovation Solution
The use of inter-fitting locating grooves on both the workpiece and workpiece holder allows for indexable positioning and re-positioning in orthogonal directions, enabling precise machining of curved features by averaging positional errors and ensuring repeatable, non-kinematic center alignment of lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional positioning methods are used, then the manufacturing process is simple, but the positioning precision and repeatability are insufficient to achieve 2 μm error tolerance
Solution Approach 1:
The positioning system is segmented into multiple independent locating grooves (at least three grooves spaced at different positions) that collectively provide redundant positioning information. Each groove contributes to the overall positioning accuracy through the averaging effect, allowing the system to achieve high precision without requiring a single complex positioning mechanism.
Solution Approach 2:
The locating grooves are pre-cut into the workpiece before the actual lens machining operation. This preliminary action establishes a precise reference framework that guides subsequent positioning operations, ensuring that each lens can be accurately located at its intended position in the array without requiring complex real-time adjustment mechanisms.
2Reliability
If indexable positioning with inter-fitting locating grooves is used, then positioning repeatability and precision are improved, but the device complexity increases
Solution Approach 1:
The positioning function is segmented across multiple locating grooves distributed at different locations on the workpiece. This segmentation creates redundancy in the positioning system, where each groove independently contributes to locating accuracy. The segmented approach allows the system to maintain high repeatability while keeping individual groove features simple and easy to manufacture.
Solution Approach 2:
The system changes the parameter of positioning from a single-point or single-line contact to a multi-point contact system defined by multiple grooves. This parameter change transforms the positioning mechanism into a more robust system that averages out local errors, improving reliability without requiring complex active control mechanisms.
3Measurement precision
If multiple inter-fitting locating grooves are used, then positional errors are minimized through averaging effect, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into two independent stages: first, cutting the locating grooves into the workpiece; second, using these grooves for positioning during lens machining. This segmentation allows each stage to be optimized independently - the grooves can be cut with standard tools, and their precision is improved by the averaging effect of multiple grooves, while the actual lens machining benefits from the pre-established reference framework.
Solution Approach 2:
The locating grooves are self-formed features that are cut into the workpiece and then automatically serve as the positioning reference for subsequent operations. The grooves themselves provide the locating function without requiring additional external fixtures or complex positioning mechanisms, making the system easier to manufacture while maintaining high precision.
Data Source
AI summary
Methods for manufacturing high precision arrays of curved features (e.g. lenses) in the surface of a workpiece are described utilizing orthogonal sets of inter-fitting locating grooves to mate a workpiece to a workpiece holder mounted to the spindle face of a rotating machine tool. The matching inter-fitting groove sets in the workpiece and the chuck allow precisely and non-kinematically indexing the workpiece to locations defined in two orthogonal directions perpendicular to the turning axis of the machine tool. At each location on the workpiece a curved feature can then be on-center machined to create arrays of curved features on the workpiece. The averaging effect of the corresponding sets of inter-fitting grooves provide for precise repeatability in determining, the relative locations of the centers of each of the curved features in an array of curved features.