Polarisation Axis Calibration Element Using Asymmetric Geometric Features
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Solution Overview
Problem
Current methods for calibrating polarisation axis measuring devices are complex and prone to systematic faults, requiring calibration bodies with known polarisation orientations, which are difficult to produce and align accurately.
Innovation Solution
A method using a calibration element with a translucent polarising material and a holder with positioning devices for precise alignment, allowing the calibration element to be inserted with either side facing the polariser, and determining the rotational position by averaging angle bisector measurements between two rotational positions, eliminating the need for a calibration body with known orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration body with known polarisation orientation is used, then the polarisation axis measuring device can be calibrated, but the production becomes complex and systematic faults occur
Solution Approach 1:
The invention extracts the essential calibration function from the complex calibration body and transfers it to a simple support element. The calibration body is replaced by a support element with merely geometric features (protrusions/indentations) that provide orientation without requiring known polarisation properties, thus eliminating the need for complex production while maintaining calibration capability
Solution Approach 2:
The support element acts as an intermediary between the measurement device and the calibration process. Instead of directly using a complex calibration body with known polarisation orientation, the support element mediates by providing a simple geometric reference that guides the calibration without itself requiring complex polarisation characteristics
2Measurement precision
If a calibration body with known polarisation orientation is used, then calibration can be performed, but alignment accuracy becomes difficult to achieve
Solution Approach 1:
The support element provides self-aligning geometric features (protrusions and indentations) that automatically guide the calibration element into the correct position. This self-service mechanism eliminates the need for complex external alignment procedures and ensures reproducible positioning without requiring high manufacturing precision in traditional alignment features
Solution Approach 2:
The support element uses asymmetric geometric features (protrusions on one side, indentations on the other) to provide unambiguous orientation. This asymmetric design ensures that the calibration element can only be inserted in the correct orientation, automatically achieving accurate alignment without requiring complex alignment procedures or high manufacturing precision
3Ease of operation
If the calibration element is inserted with either side facing the polariser, then the calibration process is simplified, but determining the correct rotational position becomes challenging
Solution Approach 1:
Instead of trying to determine which side of the calibration element should face the polariser, the invention inverts the approach: the support element's asymmetric geometric features automatically indicate the correct orientation through their physical configuration (protrusions vs. indentations), making the orientation determination trivial rather than challenging
Solution Approach 2:
The invention uses geometric 'shape changes' rather than color - the protrusions and indentations create visually distinct orientations that automatically indicate the correct positioning. This geometric signaling system makes rotational position determination immediate and unambiguous, solving the challenge of determining correct orientation while maintaining operational simplicity
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 precise and reproducible calibration of polarisation axis measuring devices, simplifying the calibration process and reducing measurement uncertainties, while allowing for reliable determination of polarisation axes in spectacle lenses.
Implementation Method 1
a calibration element (10) for insertion into a receptacle (108) of a polarisation axis measuring device (100) which is designed and intended for carrying out the method according to the invention. The calibration element (10) comprises a translucent calibration body (12) made of polarising material
Data Source
AI summary
In a method for calibrating a polarization axis measuring device, both flat sides of a calibration element in a polarization axis measuring device are irradiated with polarized light, wherein the method involves aligning in each case at least one polarization direction of the light in a first and/or second rotational position with a principal axis in a predefined angular relationship with respect to a polarization axis of the calibration element. Determining the rotational position of an axis of the calibration element is carried out by determining an angle bisector between the first and second rotational positions of the polarization direction of the incident light. The method involves assigning a predefined angle value for the rotational position of the principal axis of the polarization direction for which the latter is in the predefined angular relationship with respect to the axis of the calibration element inserted as intended. Furthermore, the invention relates to a method for determining polarization axes of spectacle lenses, to a calibration element, and to a polarization axis measuring device comprising a calibration element.