CMM Optical Probe With Tunable Focus for Variable Surface Height
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Solution Overview
Problem
Existing coordinate measuring machines (CMMs) face challenges in efficiently measuring unknown work objects without digital models, particularly in manual operations, due to the lack of feedback for guiding non-contact probes and the complexity of deriving digital models, which results in inefficient and time-consuming measurement workflows.
Innovation Solution
Equipping CMMs with an optical probe head featuring a tunable focal lens and an optical overview sensor unit to acquire surface information on-the-fly, adjusting focal length based on height information derived from the optical overview sensor, allowing for efficient and accurate measurement without requiring additional z-axis movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed focal length lens is used in the optical probe, then the device structure is simple, but the measurement precision deteriorates when measuring surfaces with varying curvature or at different distances
Solution Approach 1:
The patent applies a variable focal length lens that can dynamically adjust its focal length based on the distance to the measurement point or the curvature of the surface being measured. This dynamic adjustment capability allows the optical probe to maintain optimal focus across varying measurement conditions without requiring multiple fixed focal length lenses or complex mechanical focusing mechanisms, thus improving measurement precision while controlling device complexity.
Solution Approach 2:
The patent changes the optical parameter (focal length) of the lens to adapt to different measurement scenarios. By varying the focal length parameter according to the distance to the workpiece or surface curvature, the system achieves accurate focusing for diverse measurement conditions without requiring complex mechanical adjustments or multiple lens components.
2Adaptability or versatility
If the probe head is positioned at a fixed distance from the workpiece, then the device structure is simple, but the adaptability deteriorates when measuring surfaces with varying topography
Solution Approach 1:
The patent utilizes a variable focal length lens that can be adjusted based on the distance to different measurement points on the workpiece surface. This allows the optical probe to adapt to varying surface topography and maintain optimal focus without requiring complex mechanical positioning systems to maintain a constant probe-to-surface distance, thereby improving adaptability while controlling device complexity.
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 faster and more accurate surface measurement by continuously adjusting the focal length of the optical probe during movement, reducing the need for z-axis adjustments and enhancing measurement efficiency and precision.
Implementation Method 1
an optical probe comprising a sensor, a variable focal length lens capable of modifying its focal length
Data Source
AI summary
A coordinate measuring machine for measuring a number of measuring points on a surface, the coordinate measuring machine comprising a base, a probe head with an optical probe, a machine structure for linking the probe head to the base, at least one drive mechanism for providing movability of the probe head relative to the base, at least one encoding unit, an optical overview sensor unit arranged at the machine structure and a controlling and processing unit adapted at least for controlling the drive mechanism. The optical probe comprises an optical detection unit, in particular a sensor, a variable focal length lens capable of modifying its focal length and an actuating unit configured and arranged relative to the variable focal length lens so that the actuating unit provides setting and varying the focal length as a function of a controlling signal.