Fourier Optics Angular Spectral Measurement System
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Solution Overview
Problem
Existing methods for measuring the angular and spectral distribution of objects, such as emissive screens, are either slow due to mechanical sampling or complicated due to the need for additional optics and precise alignment, and they often have limited spectral resolution and long measurement times.
Innovation Solution
A system using a first Fourier objective to form an image on a non-flat Fourier surface, with selecting means shaped accordingly, a diaphragm for independent apparent surface observation, light-dispersion means near the diaphragm, and a third Fourier objective to image onto a Fourier plane for analysis by an imaging sensor, allowing for simultaneous angular and spectral measurement with improved spectral resolution and reduced measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fourier optics with imaging sensor is used for angular measurement, then angular distribution can be measured, but spectral resolution is limited and measurement time increases
Solution Approach 1:
The system segments the measurement function into two independent parts: a Fourier objective for angular distribution measurement and a spectrometer for spectral measurement. This segmentation allows each component to be optimized for its specific function, enabling high spectral resolution without requiring multiple sequential measurements, thus reducing measurement time.
Solution Approach 2:
The patent introduces an intermediary optical system that couples the Fourier objective with a spectrometer. This intermediary mechanism transfers light from the Fourier plane to the spectrometer entrance, allowing simultaneous acquisition of angular and spectral information without the limitations of direct imaging sensor approaches.
2Measurement precision
If mechanical photometer sampling is used, then good spectral measurement quality is achieved, but measurement speed becomes very slow
Solution Approach 1:
The patent replaces the mechanical photometer sampling system with an optical-Fourier system coupled to a spectrometer. This substitution eliminates mechanical movements and sequential sampling, allowing parallel measurement of spectral information across all wavelengths simultaneously, thereby achieving both high measurement quality and fast measurement speed.
Solution Approach 2:
The system uses periodic optical path design where light from different angles is periodically directed through the Fourier objective to the spectrometer. This periodic optical action enables continuous spectral measurement without mechanical interruptions, maintaining measurement quality while significantly improving measurement speed.
3Measurement precision
If imaging spectrometer with additional optics is used, then spectral resolution is improved, but device complexity and alignment difficulty increase
Solution Approach 1:
The patent merges the Fourier objective with the spectrometer optical path in a compact integrated design. By combining these two functional elements and optimizing their spatial relationship, the system achieves high spectral resolution without requiring separate, complex optical assemblies, thereby reducing overall device complexity and simplifying alignment procedures.
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 system enables rapid and high-resolution angular and spectral measurements with a minimal number of components, optimizing light collection and reducing alignment complexities, thus overcoming the limitations of previous methods.
Implementation Method 1
a first Fourier objective forming an image on a predetermined Fourier surface on which each point corresponds to an emission direction of the object for one particular wavelength
Implementation Method 2
light-dispersing means allowing the light coming from the selecting means to be dispersed onto or as close as possible to the diaphragm
Implementation Method 3
a third Fourier objective located after the diaphragm allowing the first Fourier surface to be imaged on a Fourier plane
Data Source
AI summary
A system for measuring the spatial distribution of the spectral emission of a measurement zone of an object, comprises: a first objective; means for selecting a portion of an image formed by the first objective; a diaphragm; light-dispersing means located in the vicinity of the diaphragm and allowing the light coming from the selecting means to be dispersed; and a second objective placed between the selecting means and the diaphragm, interacting with the first objective so that the aperture of the diaphragm is optically conjugated with the measurement zone by the first and second objectives. The first objective forms an image on a predetermined Fourier surface on which each point corresponds to an emission direction of the object for one particular wavelength. The selecting means have a selection surface shaped depending on the predetermined. Fourier surface, and the selecting means are placed on the predetermined Fourier surface.