Optical Measurement of Translucent Substrates
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Solution Overview
Problem
Existing methods and apparatuses for determining the transmission and reflection properties of large-surface coated substrates, especially in the manufacture of photovoltaic materials, are inadequate for simultaneously measuring diffuse and total transmittance, as well as reflectance from both coated and uncoated surfaces with low technical complexity.
Innovation Solution
The method employs two illuminating devices and two photodetectors, where one surface is illuminated for total transmittance and reflectance measurement, and the opposite surface for diffuse transmittance and reflectance measurement, with the order of steps varying in a measurement cycle to determine transmission and reflection properties efficiently, using integrating spheres and direction-sensitive optics to capture specific light shares.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple photodetectors and illuminating devices are used to simultaneously measure diffuse transmittance, total transmittance, and reflectance, then measurement completeness is improved, but device complexity increases
Solution Approach 1:
The patent implements periodic action by alternating the illumination between first and second illuminating devices in measurement cycles. During each cycle, the first illuminating device illuminates the first large surface while the second illuminating device illuminates the second large surface, allowing sequential measurement of transmission and reflection properties with only two photodetectors, thereby reducing device complexity while maintaining measurement completeness
Solution Approach 2:
The patent applies universality by making each photodetector perform multiple functions. The first photodetector measures both total transmittance (when second illuminating device is active) and reflectance from the second large surface (when second illuminating device is active). The second photodetector measures both diffuse transmittance (when first illuminating device is active) and reflectance from the first large surface (when first illuminating device is active). This multi-functionality reduces the number of required components
2Device complexity
If sequential measurement of transmission and reflection properties is performed, then device complexity is reduced, but measurement time increases
Solution Approach 1:
The patent implements periodic action through measurement cycles that alternately activate the first and second illuminating devices. Each measurement cycle includes: (1) activating the first illuminating device to illuminate the first large surface while the second illuminating device is deactivated, (2) activating the second illuminating device to illuminate the second large surface while the first illuminating device is deactivated. This periodic switching enables efficient sequential measurement that minimizes measurement time while maintaining simple device configuration
Solution Approach 2:
The patent applies preliminary action by pre-positioning the first and second illuminating devices on opposite sides of the object with their optical axes aligned. The first illuminating device is positioned to illuminate the first large surface, and the second illuminating device is positioned to illuminate the second large surface. This preliminary arrangement allows immediate sequential measurement without repositioning, reducing measurement time
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 allows for the determination of transmission and reflection properties with less complex equipment configuration, meeting international standards like ASTM D 1003, and enables efficient inline-process monitoring and quality inspection in the manufacturing of large-surface coated substrates.
Implementation Method 1
a first photodetector, arranged opposite the object, for measuring total transmittance (Ttotal) of the illuminating light through the object, and a second photodetector, arranged on the side of the first large surface, for measuring reflectance of the illuminating light from the first large surface
Implementation Method 2
the integrating sphere features a built-in photodetector, which receives the transmitted light and converts it into a measurement signal
Data Source
AI summary
The disclosure relates to optical measuring methods and apparatus for determining the transmission and/or reflection properties of translucent objects with utility for process monitoring and quality inspection in the manufacture of surface-coated substrates. According to the disclosure the transmission and reflection properties are determined in such a way that sequentially:a first large surface of the object is illuminated by a first illuminating device, with a photodetector measuring the total transmittance (Ttotal),a second, large surface of the object, lying opposite and parallel to the first one, is illuminated by a second illuminating device, with a photodetector measuring the diffuse transmittance (Tdiffuse), and optionallythe first large surface of the object is illuminated by the first illuminating device, with the photodetector measuring the reflectance, and/orthe second large surface of the object is illuminated by the second illuminating device,with the photodetector measuring the reflectance.