Hemispherical-elliptical BRDF Measurement System
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Solution Overview
Problem
Current 3D bi-directional reflectance distribution function (BRDF) measurement devices suffer from low optical efficiency and reliability due to secondary scattering from white hemispherical screens, leading to long signal integration times or inability to measure samples with low BRDF, and are often expensive without significant improvements in result accuracy.
Innovation Solution
A system utilizing a hemispherical-elliptical member with a highly specular or diffusely reflective inner surface to scatter electromagnetic radiation, combined with a wide-angle lens and imaging device, positioned to record the scattered light pattern, which reduces optical cross-talk and enhances measurement accuracy by accommodating pupil aberrations and allowing for adjustable reflective elements to direct radiation from various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a white hemispherical screen is used to scatter light, then the BRDF measurement can be performed, but optical cross-talk increases and measurement accuracy decreases
Solution Approach 1:
The patent removes the white hemispherical screen from the system entirely, replacing it with a black hemispherical enclosure that has a specular reflective surface at the bottom. This extraction of the problematic white screen eliminates the source of optical cross-talk while maintaining the ability to measure BRDF through controlled reflection geometry.
Solution Approach 2:
The patent converts the harmful diffuse scattering property of white surfaces into a beneficial controlled reflection system by using a black enclosure with a specular bottom surface. This transforms the measurement from uncontrolled multi-path scattering to a controlled single-bounce reflection geometry, eliminating cross-talk while preserving measurement capability.
2Productivity
If a white hemispherical screen is used to scatter light, then BRDF measurement is enabled, but optical efficiency decreases and signal integration time increases
Solution Approach 1:
The patent converts the energy-loss problem of white screens into a benefit by using a black enclosure with specular reflection. This directs scattered light efficiently toward the detector through controlled geometry, improving optical efficiency and reducing the integration time required to achieve sufficient signal levels.
3Productivity
If a 2D BRDF measurement system is used, then measurement cost is reduced, but 3D imaging capability is lost and composite image creation becomes time intensive
Solution Approach 1:
The patent segments the measurement system into distinct functional components: a light source, a black hemispherical enclosure with specular bottom, and a detector. This segmentation enables independent optimization of each component and simplifies the overall system while achieving 3D BRDF measurement capability without requiring complex multi-component assemblies.
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 system improves the accuracy and efficiency of BRDF measurements by minimizing optical cross-talk and enabling the characterization of low BRDF samples with reasonable signal integration times, while being potentially more cost-effective than existing 3D BRDF devices.
Implementation Method 1
the inner surface comprising an either a highly specular reflective surface or a diffusely reflective material formed thereon and operable to diffusely scatter electromagnetic radiation about a desired amount relative to a specular reflection angle
Implementation Method 2
operable to diffusely scatter electromagnetic radiation about a desired amount relative to a specular reflection angle
Implementation Method 3
a wide-angle lens operable to receive the electromagnetic radiation that was scattered from the portion of the sample onto the inner surface of the hemispherical member
Implementation Method 4
an imaging device operable to record intensity information imaged by the wide-angle lens to characterize the bi-directional reflectance distribution function scattered light pattern
Data Source
AI summary
A system for characterizing a bi-directional reflectance distribution function scattered light pattern of a portion of a sample is disclosed. The system can comprise a hemispherical member comprising an reflective inner surface; an entrance port operable to receive electromagnetic radiation from an electromagnetic radiation source; a first reflective optical element operable to receive at least a portion of the electromagnetic radiation and to direct the at least the portion of the electromagnetic radiation onto the portion of the sample to be characterized; a wide-angle lens operable receive the electromagnetic radiation that was specularly reflected and diffusely scattered from the portion of the sample onto the inner surface of the hemispherical member; and an imaging device operable to record intensity information imaged by the wide-angle lens to characterize the bi-directional reflectance distribution function scattered light pattern of the portion of the sample.