Optical Guide Layout for Accurate Absolute Reflectance Measurement
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Solution Overview
Problem
Existing spectrophotometers face challenges in accurately determining the absolute reflectance of an unknown sample due to differences in spectral, angular, and energy density distributions when a reference sample is positioned differently from the unknown sample, especially in large measurement areas, leading to incorrect reflectance calculations and increased noise in measurements.
Innovation Solution
An optical device with an emitting apparatus and an optical guide that minimizes these differences by using a gap for a reference sample and a reflective surface to ensure similar light distribution on both samples, allowing for accurate absolute reflectance calculations through a spectrophotometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reference sample is positioned upstream of the unknown sample, then the measurement can be performed with a single optical path, but the spectral, angular, and energy density distribution of the radiation incident on the reference and unknown sample become different
Solution Approach 1:
An optical guide (integrating sphere or light guide) is introduced as an intermediary component to transport radiation from the reference sample position to the unknown sample position. This mediator ensures that the radiation incident on both samples has identical spectral, angular, and energy density distributions, thereby enabling accurate absolute reflectance measurements while maintaining a single optical path configuration.
2Area of stationary object
If the measurement area is made large, then more sample can be analyzed, but the difference in radiation distribution between reference and unknown sample positions increases
Solution Approach 1:
The optical guide acts as a radiation distribution equalizer that couples the reference sample measurement with the unknown sample measurement regardless of their spatial separation. This allows the measurement area to be enlarged while maintaining radiation distribution consistency through the mediating optical guide, thus preserving measurement accuracy across larger areas.
3Measurement precision
If complex algorithms are used to correct reflectance measurements, then measurement accuracy can be improved, but device complexity and computational requirements increase
Solution Approach 1:
The optical guide is configured in advance to ensure that the radiation incident on both the reference sample and the unknown sample has identical spectral, angular, and energy density distributions. This preliminary arrangement of the optical path eliminates the need for complex post-measurement correction algorithms, as the radiation conditions are equalized before the measurement process begins.
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 device ensures comparable signal amplitudes for reflectance measurements, maximizing the signal-to-noise ratio and eliminating the need for complex algorithms, thereby improving measurement accuracy and reliability.
Implementation Method 1
The optical guide is internally provided with a core suitable for propagating radiation with a wavelength included in the aforesaid predefined spectral range and defining an inlet aperture at the first end and an outlet aperture at the second end
Implementation Method 2
the optical guide comprises a reflective surface that at least partially delimits the core... the reflective surface is adapted to reflect, preferably in a substantially mirror-like manner, the portion of the excitation radiation projected into the core of the optical guide
Data Source
AI summary
An optical device includes an emitting apparatus and an optical guide. The emitting apparatus includes a first aperture for emitting an excitation radiation therethrough, the excitation radiation includes at least one light radiation having a wavelength included in a predefined spectral range. The optical guide extends longitudinally between first and second ends thereof and is internally provided with a core which is suitable for propagating radiation with a wavelength included in the predefined spectral range and defining an inlet aperture at the first end and an outlet aperture at the second end, the inlet aperture facing the first aperture so as to be passed through by at least a portion of the excitation radiation when it is emitted by the emitting apparatus and the outlet aperture is directed towards an unknown sample when the optical device is in a first operating condition.