Wavelength Detector Stylus Posture Measurement
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Solution Overview
Problem
Current contact probes for coordinate measuring machines face challenges in achieving high accuracy due to thermal deformation caused by heat sources and difficulties in separating posture data from electrical noise and vibration noise, particularly in optical detection methods using PSDs and electrostrictive elements.
Innovation Solution
A wavelength detector system that simultaneously detects the wavelengths of multiple light beams by using a parallel lens group, spectroscope element, detection lens group, and multi-element photodetecting element group, allowing for precise posture calculation of a stylus without the need for separate spectroscope and photodetecting element groups, thereby isolating heat sources and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photodetecting elements are disposed close to the movable body to increase S/N ratio, then detection sensitivity is improved, but thermal deformation of the movable body increases due to heat sources
Solution Approach 1:
The patent divides the optical detection system into separate functional modules: light source unit, beam splitting unit, photodetecting element group, and wavelength detector. This segmentation allows the photodetecting elements to be positioned close to the movable body for high S/N ratio while separating heat-generating components (light source) from the movable body to minimize thermal deformation. The beam splitting unit further divides light beams into multiple paths for simultaneous wavelength detection.
Solution Approach 2:
The patent introduces optical fibers as intermediaries to transmit light beams between the light source and the movable body, and between the reflection surfaces and photodetecting elements. This allows physical separation of heat-generating light sources from temperature-sensitive components while maintaining optical coupling. The optical fibers act as mediators that decouple the thermal and optical functions.
2Speed
If PSDs are used for high-speed detection, then detection speed is improved, but ability to separate posture data from electrical noise and vibration noise deteriorates
Solution Approach 1:
Instead of using a single photodetecting element that detects the center of gravity of light distribution (which is susceptible to noise), the patent employs multiple photodetecting elements that each detect specific wavelength components. By detecting wavelengths at multiple discrete points rather than averaging over the entire light distribution, the system achieves noise immunity while maintaining detection speed. The wavelength detector further processes these signals to extract precise posture information.
3Measurement precision
If electrostrictive elements are used for posture detection, then measurement capability is improved, but device complexity and fragility increase making replacement difficult
Solution Approach 1:
The patent replaces the mechanical electrostrictive element system with an optical detection system. Instead of using piezoelectric materials that require precise mechanical integration and are fragile, the invention uses optical beams reflected from surfaces on the movable body to detect posture. This optical approach eliminates the need for fragile electrostrictive elements while maintaining measurement capability, and allows for easier replacement of the movable body since no specialized mechanical coupling is required.
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 high-accuracy, high-speed detection of stylus posture with reduced thermal deformation errors and noise interference, allowing for precise coordinate measurements even when heat sources are isolated from the probe body.
Implementation Method 1
a parallel lens group configured to convert light beams having partial wavelength ranges, which are extracted from three or more reflection light beams produced by irradiating with three or more illumination light beams having a spectrum in a prescribed wavelength range to three or more reflection surfaces of an illumination subject portion, into light beams that are parallel with each other using three or more lenses
Implementation Method 2
a spectroscope element configured to receive the light beams coming from the parallel lens group, and to output the light beams in exit directions corresponding to their partial wavelength ranges, respectively
Implementation Method 3
a detection lens group configured to condense the output light beams of the spectroscope element using three or more lenses, respectively
Implementation Method 4
a photodetecting element group configured to detect focusing positions of three or more light beams condensed by the detection lens group, respectively
Data Source
AI summary
A contact probe includes a stylus and an optical detector configured to detect a posture of the stylus optically. An illumination subject portion is formed on the stylus and has three or more reflection surfaces. The optical detector includes three or more fibers, a light source, a condenser lens group, and a wavelength detector. The wavelength detector calculates posture information of the stylus on the basis of wavelength variations of reflection light beams that are caused by variations of intervals between the condenser lens group and the three or more reflection surfaces, respectively. The contact probe acquires coordinates of a position of the contact to the object to be measured on the basis of posture information obtained by the optical detector.