Interferential Position-Measuring Device Sampling Jitter Elimination
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Solution Overview
Problem
High-speed positioning in machines requires accurate position determination across multiple axes simultaneously, but existing technologies suffer from sampling jitter due to temporal variations in position sensing, leading to errors in the range of nanometers.
Innovation Solution
An interferential position-measuring device with a switching element in the signal path downstream of the superposition location and upstream of signal-digitizing devices defines a specific sampling point in time, allowing for accurate position determination using continuous-mode light sources and avoiding sampling jitter by modulating signals after superposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If position sensing is performed at different points in time in different measurement axes, then the system can handle high traversing speeds, but sampling jitter occurs causing position errors in the range of nanometers
Solution Approach 1:
The patent applies periodic action by using a light pulse to periodically scan the measuring standard at defined time intervals. This periodic scanning ensures that position measurements across multiple measurement axes are synchronized to the same temporal reference point, eliminating sampling jitter while maintaining the ability to handle high traversing speeds. The light pulse acts as a periodic trigger that resets the measurement timing for all axes simultaneously.
Solution Approach 2:
The patent introduces a light pulse as an intermediary element that mediates between the measurement system and the moving object. This light pulse serves as a common temporal reference that synchronizes the position sensing across all measurement axes. By using this intermediary light signal, the system achieves synchronized measurements without requiring direct temporal coordination between multiple sensors, thus eliminating sampling jitter.
2Measurement precision
If a light pulse is generated in response to a request signal to define the point in time of position determination, then sampling jitter is avoided, but the complexity of the light source and signal processing increases
Solution Approach 1:
The patent applies universality by designing the light source to serve multiple functions: it generates the scanning light pulse for position measurement, provides temporal synchronization for all measurement axes, and acts as a reference signal for the measurement system. This multi-functional light source reduces overall system complexity compared to having separate synchronization mechanisms and light sources for each function.
Solution Approach 2:
The patent merges the synchronization function and measurement function into a single light pulse generation process. Instead of having separate synchronization signals and measurement light sources, the system combines these functions into one integrated light pulse that simultaneously provides both temporal reference and measurement illumination, thereby reducing device complexity.
3Measurement precision
If high-power pulsed light sources are used to define sampling points in time, then position measurement accuracy is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The patent applies continuity of useful action by using a continuous-mode light source that continuously provides illumination for position measurement, rather than relying on intermittent high-power pulses. The continuous light source is modulated by the switching element to define sampling points, but the underlying light generation remains continuous, reducing energy consumption compared to high-power pulsed sources while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the operational parameters of the light source from high-power pulsed mode to continuous-mode with optical modulation. By using a continuous light source that is switched or modulated by the switching element rather than relying on high-power pulses, the system achieves the same sampling point definition with lower energy consumption and reduced thermal effects.
4Measurement precision
If switching elements are introduced in the signal path to define sampling points in time, then sampling jitter is eliminated, but the device complexity increases
Solution Approach 1:
The patent replaces mechanical synchronization mechanisms with an optical switching element that operates in the signal path. Instead of using mechanical devices to coordinate measurements across multiple axes, the system uses an optical switch that can rapidly modulate the light signal to define sampling points, achieving higher precision with reduced mechanical complexity.
Solution Approach 2:
The switching element acts as an intermediary in the signal path that defines sampling points without requiring complex coordination between multiple measurement systems. By placing the switch in the optical signal path rather than in electrical control circuits, the system achieves precise temporal definition with simpler control architecture.
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 highly accurate and drift-resistant position measurement, reducing the complexity of light sources and signal processing, and eliminating the need for high-power pulsed light sources, thus achieving precise position sensing across multiple axes without temporal offsets.
Implementation Method 1
The sub-beams are subsequently superimposed and interfered at a superposition location and at least one resulting signal beam propagates toward an evaluation unit
Data Source
AI summary
An interferential position-measuring device determines a position of an object which is disposed to be movable along a measurement direction. A light source is configured to emit a beam which is split into two sub-beams. One of the sub-beams impinges on an optical functional element on the object. The sub-beams are subsequently superimposed and interfered at a superposition location and a resulting signal beam propagates toward an evaluation unit configured to generate a position-dependent measurement signal from the resulting signal beam. A switching element is disposed in the signal path downstream of the superposition location and upstream of a signal-digitizing device. The switching element is configured to define a specific sampling point in time.