Polarized Light Surface Data Determination for Transparent Objects
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Solution Overview
Problem
Existing methods for determining surface data of transparent objects, such as spectacle lenses, face challenges in accurately measuring surface data due to superimposed reflections from both surfaces, leading to ambiguous light intensities and difficulties in evaluation.
Innovation Solution
The method employs polarized light with a polarizer and analyzer to suppress undesired reflections, allowing for reliable measurement of surface data by adjusting the polarization to differentiate between reflections from the front and rear surfaces, thereby enhancing measurement accuracy and clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reflectometry is used to measure transparent objects, then surface data can be determined, but reflections from both front and back surfaces superimpose causing ambiguous light intensities and difficult evaluation
Solution Approach 1:
The patent changes the polarization parameter of the incident light and the analysis polarization of the detected light to differentiate between reflections from the front and back surfaces. By adjusting these polarization parameters, the superimposed reflections can be separated, resolving the ambiguity in light intensity evaluation while maintaining measurement precision.
2Measurement precision
If full-area patterns are projected sequentially for measurement, then complete surface coverage is achieved, but measurement time increases and productivity decreases
Solution Approach 1:
The patent segments the measurement process by using discrete pattern elements instead of full-area patterns. Each pattern element can be independently projected and measured, allowing for more efficient processing while maintaining complete surface coverage. This segmentation approach reduces the time required to measure the entire surface.
Solution Approach 2:
The patent employs periodic projection of pattern elements across the surface. By systematically projecting discrete patterns in a periodic manner and using polarization differentiation to identify surface reflections, the method achieves complete surface coverage without requiring sequential full-area pattern projection, thereby improving measurement speed.
3Measurement precision
If polarized light with polarization adjustment is used to suppress unwanted reflections, then measurement clarity improves, but device complexity increases
Solution Approach 1:
The patent introduces polarizers and analyzers as intermediary optical elements between the light source and the object, and between the object and the detector. These intermediaries selectively transmit and analyze polarized light to differentiate between front and back surface reflections. While they add some device complexity, they enable precise measurement clarity and reflection suppression.
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 approach enables reliable and accurate determination of surface data, including height, inclination, and curvature, by selectively suppressing or emphasizing reflections, thus improving the quality of surface measurement and quality control of transparent objects.
Implementation Method 1
illumination of an analysis area of the object to be examined by at least one illumination device with polarized light with a single-beam polarization, wherein the light is guided through a polarizer associated with or integrated into the illumination device to adjust the single-beam polarization
Implementation Method 2
reception of light reflected from the first and second surfaces of the object with an analysis polarization by means of at least one receiving device
Implementation Method 3
at least partially suppressing unwanted light intensity reflected from the first or second surface of the object and received by the recording device by adjusting the polarization of the polarizer and/or the analysis polarization of the analyzer
Data Source
Figure 1~2
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AI summary
The invention relates to a method and an apparatus for determining surface data (16, 18) and/or measurement data relating to a surface (12, 14), in particular for the quality control of an at least partially transparent object (10), in particular an ophthalmic lens, having an optically active first surface (12) and an opposite optically active second surface (14). The method comprises irradiating polarized light with an irradiation polarization from at least one illumination device (101) onto an analysis area (34) of the object (10) to be examined, wherein, for the purpose of setting the irradiation polarization, the light is passed through a polariser (108) assigned to the illumination device (101) or integrated in the latter, and receiving light which is reflected at the first and/or second surface (12, 14) and has an analysis polarization by means of at least one receiving device (102), wherein the light is passed through an analyser (110) assigned to the receiving device (102) or integrated in the latter. The method also comprises at least partially suppressing an undesirable light intensity reflected by the first or second surface (12, 14) and received by the receiving device (102) by setting the irradiation polarization of the polariser (108) and/or the analysis polarization of the analyser (110), and measuring an intensity distribution (22, 23) or a wave front (24, 25) of the light received with the analysis polarization in order to determine surface data (16, 18) and/or measurement data relating to the surface (12, 14) in the analysis area (34).