Interferometer Calibration via Pivoted Plane
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Solution Overview
Problem
Interferometers, particularly OCT scanners, face challenges in achieving precise calibration due to unaccounted error sources and limited accuracy, often relying on individual support points with interpolation, which can lead to incomplete measurement correction.
Innovation Solution
A method involving a first plane pivoted by a specific angle within the interferometer's beam path, allowing interferometric measurement of axial distances between points to calibrate the lateral position and direction of the measuring beam, enabling comprehensive error consideration and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If individual support points are measured exactly with interpolation between them, then measurement complexity is reduced, but measurement precision deteriorates due to unaccounted error sources
Solution Approach 1:
The patent transitions from measuring only axial distances at individual support points to measuring both axial distances and lateral positions of multiple points on a calibration plane. By pivoting the calibration plane to a specific angle and measuring the lateral distance between points in addition to axial distances, the calibration process accounts for multiple error sources including lateral beam position and direction, thereby improving measurement precision without excessive complexity increase
Solution Approach 2:
The patent introduces a specifically designed calibration plane with known point positions as an intermediary object. This calibration plane serves as a mediator between the interferometer and the measurement process, allowing systematic characterization of beam errors. By using this intermediary with precisely known geometry, the system can detect and correct multiple error sources that would otherwise remain unaccounted for
2Ease of operation
If conventional calibration methods are used with assumed known geometries, then calibration process is simplified, but reliability deteriorates due to unaccounted error sources
Solution Approach 1:
The patent changes the calibration approach by introducing a calibration plane pivoted at a specific non-zero angle relative to the beam path, rather than using conventional perpendicular arrangements. This parameter change (the pivot angle) enables the system to capture additional error information including lateral beam direction errors. The method also changes from measuring single points to measuring multiple points with known lateral separations, thereby improving reliability while maintaining operational simplicity through automated measurement sequences
3Area of stationary object
If interpolation is used between support points, then measurement coverage is improved, but measurement precision deteriorates due to unaccounted error sources
Solution Approach 1:
The patent applies preliminary action by precisely characterizing the beam behavior at multiple known points on the calibration plane before actual measurements are performed. By measuring axial distances and lateral positions at multiple predetermined points with known geometries, the system pre-determines correction factors for lateral beam position and direction errors. This preliminary characterization enables accurate interpolation during actual measurements, improving both coverage and precision
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 enables precise calibration of interferometers by accounting for multiple error sources, improving measurement accuracy and correcting future data, thus enhancing the overall precision and efficiency of the calibration process.
Implementation Method 1
In interferometry, measurements are carried out using the superposition of waves
Implementation Method 2
at least one plane that at least partially reflects the measuring beam is introduced into the beam path
Data Source
Figure 1~2
Figure 3~4
AI summary
In a method for calibrating an interferometer (100) with a beam path for a measuring beam (112), wherein at least one plane (320) which reflects the measuring beam (112) at least partially is introduced into the beam path, and wherein a normal of a first plane (320) to a measuring beam (112) appearing on the first plane (320) is pivoted by a first angle, the following steps are carried out: interferometric measurement of a first axial distance of a first point on the first plane (320) with the measuring beam (112), as well as interferometric measurement of a second axial distance of a second point on one of the at least one plane (320) with the measuring beam (112), wherein the second point is spaced apart from the first point.