Confocal-Chromatic Beam Splitting for Rough Surface Measurement
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Solution Overview
Problem
Conventional confocal-chromatic measuring methods face measurement uncertainties due to rough surfaces and diffusely scattering materials, leading to location-dependent noise and low signal-to-noise ratios, especially in areas with steep profile flanks and microstructures.
Innovation Solution
A device and method that divides measuring light into multiple partial beams, allowing simultaneous measurement at laterally offset points, with optical averaging of reflections to generate a summed, spectrally coded signal, using an optical device between the illumination and confocal-chromatic optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional confocal-chromatic measurement is used on rough surfaces, then the measurement can be performed, but measurement uncertainties and location-dependent noise increase significantly
Solution Approach 1:
The illumination diaphragm is divided into multiple illumination areas that generate separate measuring light partial beams. Each partial beam measures a different measuring point on the object, and the measurements are combined through optical averaging to reduce location-dependent noise and improve reliability on rough surfaces.
Solution Approach 2:
Multiple detection light partial beams from different measuring points are optically combined and superimposed in the detection path. This optical averaging merges the signals to reduce noise and improve measurement precision while maintaining a compact system structure.
2Reliability
If multiple measuring points are measured simultaneously, then measurement reliability improves, but device complexity increases
Solution Approach 1:
An optical device with beam-splitting and beam-combining functionality is introduced as an intermediary between the illumination and detection paths. This intermediary enables multiple measuring points to be measured simultaneously while keeping the overall system structure relatively simple through optical rather than electronic combining.
3Measurement precision
If the illumination diaphragm is divided into multiple areas, then noise is reduced through averaging, but the structure becomes more complex
Solution Approach 1:
The illumination diaphragm is segmented into multiple illumination areas, each generating a measuring light partial beam that targets a specific measuring point. This segmentation enables optical averaging across multiple points, improving signal-to-noise ratio while the segmented structure itself serves as the dividing mechanism.
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
Enhances signal-to-noise ratio, reduces measurement noise, and improves distance and thickness measurement accuracy by averaging over multiple points, adapting to microstructures and maintaining compatibility with existing systems.
Implementation Method 1
Due to the dispersion of the confocal-chromatic optical system, the different wavelengths of the measuring light have different focal points.
Implementation Method 2
an optical device is arranged between the illumination diaphragm and the confocal-chromatic optical system, wherein the optical device divides measuring light emerging from the illumination diaphragm into multiple partial beams of measuring light
Implementation Method 3
the detection light reflected by the object being measured is detected via the same confocal-chromatic optical system onto a receiving aperture acting as a confocal diaphragm and the dominant wavelength of the reflected detection light is determined using a spectrometer
Data Source
AI summary
A device for confocal-chromatic, preferably one-dimensional, distance and/or thickness comprises measurement an illumination diaphragm, a confocal-chromatic optical system, and an optical device arranged between the illumination diaphragm and the confocal-chromatic optical system. The optical device splits measuring light emerging from the illumination diaphragm into a plurality of partial beams of measuring light. After passing through the confocal-chromatic optical system, the partial beams of measuring light strike the object to be measured at laterally offset measuring points. The partial beams of measuring light reflected from the measuring points fall onto a receiving diaphragm via the confocal-chromatic optical system and the optical device. After passing through the receiving diaphragm, the partial beams of measuring light result in a common beam of detection light. The disclosure also relates to an apparatus and to a method for confocal-chromatic, preferably one-dimensional, distance and/or thickness measurement.