Ultraprecise Centering of Aspherical Optics Using Single Sensor Scanning
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Solution Overview
Problem
Existing methods for centering aspherical or freely formed optics are limited by the inability to precisely determine the optical axis, leading to errors that exceed tolerance requirements due to the need for multiple sensors and lack of precise mechanical positioning, especially in ultra-precise centering lathes.
Innovation Solution
A method utilizing a single sensor for scanning the optics' surface to determine the position and orientation of aspherical surfaces, eliminating the need for autocollimators, and using machine control algorithms to calculate and correct decentering and tilting, with optional inclusion of radius compensation, allowing for precise machining of reference surfaces to align the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors (autocollimator and additional sensor) are used for measuring aspherical surfaces, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple sensors into a single sensor system. The single sensor is capable of performing both autocollimator measurements and additional sensor measurements by being positioned and controlled to scan the aspherical surface, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The single sensor is designed to perform multiple measurement functions. It can measure both the spherical approximation and the aspherical surface geometry by scanning in different patterns and positions, making it a universal measurement tool that replaces multiple specialized sensors
2Device complexity
If conventional centering workstations with fixed sensor positions are used, then device complexity is reduced, but measurement precision deteriorates due to lack of precise mechanical positioning axes
Solution Approach 1:
The patent transitions from fixed sensor positions to dynamic sensor positioning. The single sensor is moved along precisely controlled linear and rotary axes during the measurement process, allowing it to access different positions and angles on the aspherical surface, thereby achieving high measurement precision without requiring multiple fixed sensors
3Ease of manufacture
If spherical approximation is used for aspherical surfaces, then measurement process is simplified, but manufacturing precision deteriorates due to errors exceeding tolerance requirements
Solution Approach 1:
The patent performs a preliminary spherical approximation measurement to establish initial reference data, then uses this as a basis for more precise aspherical surface scanning. This preliminary action simplifies the overall process while ensuring final precision by using the rough spherical model as a starting point for detailed aspherical measurement
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 approach simplifies ultra-precise centering by reducing costs and improving accuracy, enabling precise alignment of aspherical optics without the need for multiple sensors, achieving sub-micron translational and rotational offsets within tight tolerance limits.
Implementation Method 1
Only one sensor is scanned with the axes of an ultra-precise centering lathe over the surface of an aspherical or free-form surface of an optic whose orientation is not known.
Implementation Method 2
From this, point or line data can be recorded. Then, using routines in the machine control or a coupled computer, the position is calculated as decentering and tilting of the optics
Implementation Method 3
Subsequently, reference surfaces of the optics, the lens mount or the lens itself are correctively processed by ablating methods on the basis of the previously determined measurement data
Data Source
AI summary
The invention relates to a method for ultraprecise centering of a lens (25) having an aspherical front lens face, which has an axis of symmetry (29), and an opposing rear lens face, wherein the lens is gripped in an ultraprecise centering lathe. Surface data are determined by scanning and guiding of a sensor over the front lens face with the axes (30) of the ultraprecise centering lathe. From these surface data the position of the front lens face in relation to a reference axis (30) of the centering lathe is determined and subsequently reference surfaces of the lens or of a lens mount (26) are machined correctively by the centering lathe in an abrasive process in such a way that the axis of symmetry (29) or a weighted optical axis lies in a defined position relative to the reference surfaces.