Touch Probe Optical Path Lengthening for High Resolution
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Solution Overview
Problem
Existing touch probes require a significant stylus deflection for detection, leading to reduced sensitivity and accuracy in measuring movements.
Innovation Solution
A touch probe design incorporating a light source, reflective elements, and a membrane with a light beam that is reflected multiple times between two mirrors, enhancing the optical path and resolution, and a membrane that improves radial measurement characteristics and dampens external vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sensor element (photodetector) is used to detect stylus deflection, then the device structure remains simple, but the sensitivity is insufficient requiring large deflection for detection
Solution Approach 1:
The patent transforms the measurement from direct spatial deflection detection to optical path length detection. By using a light beam that travels along the stylus axis and reflects between mirrors, small angular deflections are converted into measurable optical path differences, effectively measuring in a different dimensional domain (optical path vs. mechanical displacement).
Solution Approach 2:
The patent introduces light beams and reflective mirrors as intermediary elements between the stylus and the sensor. Instead of directly detecting mechanical deflection, the system uses optical intermediaries to transduce the mechanical movement into optical signal variations that can be measured with high precision by photodetectors.
2Measurement precision
If the optical path length is increased to improve resolution, then the measurement precision improves, but the device size increases
Solution Approach 1:
The patent employs a nested optical configuration where mirrors are positioned to create multiple reflections within a compact volume. The light beam bounces between mirrors arranged in a nested or folded pattern, effectively extending the optical path length without proportionally increasing the physical housing volume, similar to how nested dolls pack multiple levels within a limited space.
Solution Approach 2:
The patent uses folded optical paths and multi-axis mirror arrangements to extend the effective measurement length in three-dimensional space without increasing the linear dimensions of the housing. By utilizing spatial folding and angular reflections, the system achieves long optical paths within compact geometries.
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
The solution enhances the sensitivity and accuracy of stylus deflection detection with improved resolution and reduced impact from external vibrations, allowing for precise radial probing and maintaining uniform contact characteristics.
Implementation Method 1
the first reflective element is arranged on the stylus holder to direct a light beam from the light source to the sensor means
Implementation Method 2
The second reflecting element makes it possible to lengthen the optical path of the light beam by positioning the first and second reflecting elements in such a way that the light beam is reflected multiple times between them
Implementation Method 3
The sensor means include, for example, a photodetector. One sensor means, instance, is designed as a photodiode
Data Source
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AI summary
The invention relates to a touch probe, comprising a housing, a stylus holder and a rest position mechanism, by means of which the stylus holder is mounted on the housing, the stylus holder being designed to arrange a stylus, a light source, sensor means, and a first reflective element, wherein the first reflective element is arranged on the stylus holder in order to guide a light beam of the light source to the sensor means. The touch probe is characterized in that said touch probe comprises a second reflective element.