Interferometric Correction Means for Wavelength Variation Compensation
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Solution Overview
Problem
High-precision interferometric measurements are affected by ambient conditions such as temperature, pressure, and humidity, leading to wavelength variations that compromise measurement accuracy in coordinate measuring devices, as existing solutions often measure corrections remotely and do not account for local changes effectively.
Innovation Solution
An interferometric measuring device with an interferometric correction means positioned proximate to the measuring means along a significant portion of the positioning stage's traversing path, allowing for direct detection and correction of wavelength variations due to ambient conditions, thereby enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometric correction means is positioned remotely from measuring means, then device complexity is reduced, but measurement precision deteriorates due to inability to account for local ambient condition changes
Solution Approach 1:
The patent combines the interferometric measuring means and interferometric correction means into a single integrated device. The correction means is positioned in close proximity to the measuring means, allowing both functions to share the same physical space and optical infrastructure. This merging enables accurate local environmental monitoring without requiring a separate remote correction system, thereby maintaining measurement precision while avoiding the complexity of distributed sensor networks.
Solution Approach 2:
The interferometric correction means acts as an intermediary that locally measures ambient conditions (temperature, pressure, humidity) between the laser source and the measurement point. By positioning the correction means in close proximity to the measuring means, it mediates the wavelength variations caused by local environmental changes, providing real-time correction data that compensates for ambient influences on the interference pattern.
2Measurement precision
If interferometric correction means is positioned proximate to measuring means, then measurement precision is improved by detecting local ambient changes, but device complexity increases
Solution Approach 1:
The integrated interferometric device performs multiple functions within a single configuration: it simultaneously conducts position measurements and environmental correction measurements. The beam splitter directs portions of the laser beam to both the measuring mirror and the correction means, allowing the system to gather both measurement data and environmental correction data through a unified optical path and processing system, thereby reducing the need for separate dedicated systems.
Solution Approach 2:
The system dynamically adjusts measurement parameters based on real-time environmental conditions detected by the correction means. As ambient conditions (temperature, pressure, humidity) change, the correction means measures the resulting wavelength variations and uses this information to compensate for parameter drift in the main measurement. This adaptive parameter adjustment maintains measurement precision without requiring additional hardware complexity.
3Measurement precision
If climatic chamber is used to maintain constant ambient conditions, then measurement precision is improved, but productivity deteriorates due to restricted access and complex environmental control
Solution Approach 1:
The interferometric correction means continuously monitors ambient conditions and provides real-time feedback on wavelength variations to the measurement system. This feedback loop enables dynamic compensation for environmental changes during measurements, allowing the system to maintain high precision without requiring a controlled climatic chamber. The feedback mechanism processes correction data and adjusts measurements accordingly, eliminating the need for restrictive environmental enclosures.
Solution Approach 2:
The measurement system performs its own environmental correction through the integrated correction means, eliminating the need for external climatic control infrastructure. The correction means autonomously measures local ambient conditions, calculates wavelength variations, and applies corrections to the position measurements. This self-correcting capability allows the system to operate in normal ambient conditions while maintaining measurement precision, thereby improving productivity by removing access restrictions and complex environmental control requirements.
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 configuration enables precise correction of ambient influences, significantly improving the accuracy of relative position determination by directly addressing local changes in temperature, pressure, and humidity, ensuring high precision in coordinate measurements.
Implementation Method 1
Interferometric measuring means are often used for highly precise distance and position measurements. In a high-precision interferometric measurement the relative difference in distance between a measuring beam and a reference beam is usually measured with the beam path of an interferometric measuring means.
Implementation Method 2
The current value of the wavelength of a light beam is a function of the refractive index of the medium passed by the light beam. The refractive index varies, for example, due to gradual variations or rapid fluctuations of the temperature, air pressure and moisture, or due to changes in the air composition.
Data Source
AI summary
A measuring apparatus for determining relative positions of a positioning stage arranged in a moveable fashion in at least one direction by a predeterminable maximum traversing path. The measuring device comprises at least one interferometric measuring means and at least one interferometric correction means. An interferometric measuring means is operable with the laser light of a laser of at least one wavelength. Correction results can be generated with the interferometric correction means allowing conclusions to be drawn with respect to the actual wavelength of the laser light during a position determination of the positioning stage in order to take into account variations of the wavelength of the laser light, in particular due to ambient conditions, when evaluating the measuring results. The interferometric correction means is arranged proximate to the interferometric measuring means, and the proximity corresponds to a predeterminable portion of the maximum traversing path of the positioning stage.