Double Ellipsoidal Optical System for Hemispherical Reflectance Measurement
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Solution Overview
Problem
Conventional scatterometers face challenges in efficiently measuring hemisphere total reflectance and transmittance, and light distribution with high precision, due to issues such as multiple reflections, limited measurement capabilities, and long measurement times.
Innovation Solution
A double ellipsoidal optical system with a belt-shape and quarter or octantal ellipsoidal mirrors, combined with a hemispherical detection optical system, allows for simultaneous detection of all reflected light, reducing multiple reflections and enabling efficient measurement of hemisphere total reflectance, transmittance, and light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional scatterometer using a hemispheroidal mirror is used to measure hemisphere total reflectance, then the measurement can be performed, but multiple reflections occur causing measurement precision degradation
Solution Approach 1:
The hemispheroidal mirror is divided into a light-entering ellipsoidal mirror and a light-receiving ellipsoidal mirror, with the sample positioned at their common focal point. This segmentation allows incident light to enter through the first mirror, reflect off the sample, and be collected by the second mirror, eliminating multiple reflections between a single mirror surface while maintaining hemisphere total reflectance measurement capability
Solution Approach 2:
The sample positioned at the common focal point of the two ellipsoidal mirrors acts as an intermediary that converts incident light into reflected light without causing multiple reflections. The dual-ellipsoidal system serves as an intermediary optical path that guides light from the source through the sample to the detector, preventing harmful multiple reflections
2Adaptability or versatility
If separate accessories are used to measure specular reflectance and transmittance, then both measurements can be performed, but measurement precision differs between the two measurements
Solution Approach 1:
The dual-ellipsoidal optical system with the sample at the common focal point serves multiple functions: it measures hemisphere total reflectance by collecting reflected light, measures hemisphere total transmittance by allowing light to pass through the sample and be collected by the second mirror, and can measure absolute specular reflectance and transmittance. This single integrated system replaces separate accessories while maintaining consistent measurement precision across all measurements
Solution Approach 2:
The optical paths for reflectance and transmittance measurements are merged into a single dual-ellipsoidal system. The light-entering ellipsoidal mirror and light-receiving ellipsoidal mirror work together to simultaneously enable both reflectance and transmittance measurements with the same optical components, eliminating the need for separate accessories and ensuring consistent measurement precision
3Measurement precision
If conventional scatterometers measure light distribution by scanning through 4π space, then complete scattering can be measured, but measurement time becomes excessively long
Solution Approach 1:
The use of ellipsoidal mirrors with specific curvature properties allows the system to capture light distribution over a hemisphere in a single measurement. The ellipsoidal geometry naturally focuses light from the entire hemisphere onto the focal point, eliminating the need for time-consuming scanning through 4π space while maintaining complete light distribution measurement capability
Solution Approach 2:
The dual-ellipsoidal system continuously collects light from the entire hemisphere simultaneously in a single measurement event, rather than requiring sequential scanning. The light-receiving ellipsoidal mirror continuously gathers reflected or transmitted light from all angles and focuses it at the common focal point, enabling rapid light distribution measurement without interruption or scanning
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 configuration enables high-precision, rapid measurement of hemisphere total reflectance and transmittance, as well as light distribution, while also allowing for absolute specular reflectance and transmittance measurements, overcoming the limitations of existing technologies.
Implementation Method 1
a double ellipsoidal optical system composed of a partial ellipsoidal mirror and a belt-shape ellipsoidal mirror
Implementation Method 2
a hemispherical detection optical system... allows for simultaneous detection of all reflected light
Data Source
AI summary
In an apparatus for measuring an optical characteristic of a sample, one object of the present invention is to provide an apparatus capable of measuring hemispherical total reflectance, hemispherical total transmittance, and light distribution, and to achieve a reduction in measurement time and an improvement in precision of the quantitative analysis of hemispherical total reflectance (transmittance). In a double ellipsoidal optical system which is an optical system in which one focal points of two ellipsoidal mirrors are positioned as a common focal point, and three focal points are aligned in a straight line, the double ellipsoidal optical system is composed of a partial ellipsoidal mirror 2, such as a quarter ellipsoidal mirror, and a belt-shape ellipsoidal mirror 1. By disposing, on a position of a focal point of the partial ellipsoidal mirror, a hemispherical detection optical system having a hemispherical lens or a rotational parabolic mirror, light scattered by an object, reflected by the partial ellipsoidal mirror, and focused on the point is photographed by for example a CCD camera 6 via a hemispherical lens and a taper fiber 5 so as to measure an optical characteristic of the object.