Angle-Selective Optical Filtering With Dielectric Multilayer Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spatial frequency filters require precise mechanical alignment between focusing optical systems and spatial filters, which are susceptible to changes due to external factors like vibration and temperature, leading to variations in frequency properties.
Innovation Solution
An optical apparatus with an angle filter using a dielectric multilayer film, where dielectric layers with different refractive indices are alternately stacked, is positioned on the optical path between focusing optical elements, allowing control of transmittance and reflectance based on incident angle, thereby stabilizing frequency properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spatial filter with aperture is disposed on the Fourier plane including the rear focal point of the focusing optical system, then frequency component extraction or removal can be achieved, but the relative position between the focusing optical system and the spatial filter must be adjusted with extremely high accuracy and is susceptible to external factors such as vibration and temperature
Solution Approach 1:
The patent replaces the mechanical spatial filter system (requiring precise mechanical alignment) with an angle filter system based on optical principles. The angle filter uses a dielectric multilayer film that selectively transmits or reflects light based on incident angle rather than requiring precise mechanical positioning, thereby substituting a mechanically sensitive system with an optically stable one.
Solution Approach 2:
The patent changes the filtering parameter from spatial position (mechanical alignment) to incident angle (optical parameter). By controlling the incident angle of light on the dielectric multilayer film, the filter can selectively transmit or reflect specific frequency components without requiring precise mechanical positioning, thus improving reliability against external disturbances.
2Manufacturing precision
If a spatial filter is mechanically precisely adjusted to achieve accurate frequency filtering, then desired frequency components can be extracted, but the filtered frequency property varies due to external factors such as vibration and temperature
Solution Approach 1:
The patent eliminates the need for mechanical precision adjustment by using an angle filter that operates based on optical principles. The dielectric multilayer film inherently filters light based on incident angle, removing the dependency on mechanical alignment and thus reducing sensitivity to vibration and temperature changes.
Solution Approach 2:
Instead of trying to maintain precise mechanical alignment against external disturbances, the patent inverts the approach by using a filter mechanism that is inherently insensitive to such disturbances. The angle filter uses optical path differences and incident angles rather than fixed mechanical positions, turning the vulnerability of mechanical systems into an advantage of optical systems.
3Reliability
If the incident angle of light is controlled through the dielectric multilayer film's layer structure, then transmittance and reflectance can be controlled to stabilize frequency properties, but the filter structure becomes more complex
Solution Approach 1:
The patent controls filtering characteristics by changing parameters of the dielectric multilayer film such as layer thickness, refractive index, and number of layers. By adjusting these parameters, the filter can be designed to transmit or reflect specific incident angles corresponding to desired frequency components, achieving stable frequency filtering without complex mechanical systems.
Solution Approach 2:
The patent uses a composite dielectric multilayer film structure with alternating high and low refractive index layers. This composite structure enables precise control over optical properties including transmittance and reflectance at different incident angles, providing stable frequency filtering performance through material composition rather than mechanical complexity.
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 optical apparatus effectively suppresses changes in frequency properties due to positional shifts, enabling stable frequency component extraction or rejection by controlling incident angles through the dielectric multilayer film's layer structure, thickness, and material properties.
Implementation Method 1
a transmittance and a reflectance of the dielectric multilayer film change according to an incident angle of light
Implementation Method 2
dielectric layers having a first refractive index and dielectric layers having a second refractive index lower than the first refractive index are alternately stacked
Data Source
AI summary
An optical apparatus includes an angle filter disposed on an optical path in the middle of focusing or in the middle of divergence by a focusing optical element. The angle filter includes a dielectric multilayer film in which dielectric layers having a first refractive index and dielectric layers having a second refractive index lower than the first refractive index are alternately stacked.