Laser Tracker Optical Reference Decoupling
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Solution Overview
Problem
Existing high-precision laser trackers face challenges in achieving submicrometer precision due to the complexity of aligning optical and mechanical components, and the need for tight mechanical and optical tolerances.
Innovation Solution
The laser tracker decouples the optical reference surface from the mechanical datum, using a revolution body shaped datum as a mechanical guide for the optics unit, which maintains contact with the datum via a force supply arrangement, such as a spring-pair or magnetic elements, to ensure precise movement and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the physical datum acts as an optical reference surface, then measurement precision can be achieved, but complex optics and very tight mechanical and optical tolerances are required
Solution Approach 1:
The patent divides the system into two separate functional components: a mechanical datum that provides positional reference and an optical reference surface that provides optical reference. This segmentation allows each component to be optimized independently, reducing the overall complexity compared to a unified physical datum serving dual purposes.
Solution Approach 2:
The patent introduces an intermediary optical reference surface that is separately positioned relative to the mechanical datum. This intermediary element decouples the optical reference function from the mechanical datum, allowing the optical system to reference a stable, dedicated surface rather than relying on the mechanical datum's optical properties.
2Stability of the object's composition
If the mobile components are mechanically decoupled from the physical datum, then positional and thermal stability are improved, but high accuracy steering mechanisms and control are required to follow the datum surface
Solution Approach 1:
The patent segments the reference functions by providing a dedicated optical reference surface that remains stationary relative to the mechanical datum. This allows mobile components to maintain a simple, fixed geometric relationship with the optical reference rather than requiring complex steering to follow a moving datum surface.
Solution Approach 2:
The patent creates a geometric copy or representation of the datum surface through the optical reference surface. Instead of mobile components physically following the datum surface, they reference a stationary optical copy that preserves the necessary geometric relationships, eliminating the need for high-accuracy steering.
3Measurement precision
If submicrometer precision is required, then measurement accuracy improves, but alignment of multiple components becomes tedious and difficult
Solution Approach 1:
The patent segments the alignment requirements by providing a dedicated optical reference surface with known optical properties. This allows the optical system to be aligned to a stable reference rather than requiring complex coordination between multiple moving components, significantly easing the alignment process.
Solution Approach 2:
The optical reference surface provides self-aligning properties through its stationary, well-defined geometric relationship with the mechanical datum. The system uses the inherent stability and known geometry of the optical reference to automatically establish proper alignment, reducing the need for manual adjustment and coordination.
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 simplifies the mechanical and optical constructs, reduces the influence of mechanical deformations on precision, and achieves better than 1 μm precision in distance measurements, while maintaining the stability and accuracy required for high-precision applications.
Implementation Method 1
a force supply arrangement configured to provide a contact force between the contacting surface and the datum
Implementation Method 2
a force supply arrangement, such as a spring-pair or magnetic elements
Data Source
AI summary
A laser tracker for a distance measurement to a target point using a measuring beam. A target axis of the measuring beam can be swivelled around a nodal point inside a revolution body shaped datum fixedly arranged inside a housing of the laser tracker. The laser tracker comprises an optical arrangement providing a measurement path to the target point and an internal reference path. The optical arrangement comprises an optics unit embodied as mechanically fixed arrangement and the laser tracker comprises a force supply arrangement providing a force acting on the optics unit (as a whole) causing the optics unit to maintain contact with the surface of the datum.