Tilted Interference Filter in Cylindrical Housing for Back Reflection Control
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Solution Overview
Problem
Existing optical components with interference filters face challenges in reducing back reflected light, leading to increased production costs due to complex techniques required for light-absorbing coatings or conical holes in the housing, which complicates the manufacturing process.
Innovation Solution
An optical component design featuring a hollow cylindrical housing with specific optical path sections and collimator lenses, where the opening diameter of the optical path sections is smaller than the apparent diameter of the collimator lenses, and the interference filter is tilted to direct reflected light inward, preventing back reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If light-absorbing coatings or conical holes are applied to the housing inner surface, then back reflected light is reduced, but production cost increases and manufacturing complexity increases
Solution Approach 1:
The patent extracts the light-absorbing function from the housing structure by introducing a separate light-absorbing member positioned in the optical path. This separates the housing's structural function from the light management function, allowing the housing to be manufactured simply while still achieving back reflected light reduction through the dedicated light-absorbing component.
Solution Approach 2:
The patent introduces a light-absorbing member as an intermediary element between the interference filter and the housing. This intermediary component absorbs stray light before it can reflect off the housing inner surface and return to the optical fiber, eliminating the need for complex housing treatments while achieving the same light management goal.
2Object-affected harmful factors
If light-absorbing coatings or conical holes are applied to the housing inner surface, then back reflected light is reduced, but production cost increases
Solution Approach 1:
The patent extracts the light-absorbing function from the housing structure by introducing a separate light-absorbing member positioned in the optical path. This separates the housing's structural function from the light management function, allowing the housing to be manufactured simply while still achieving back reflected light reduction through the dedicated light-absorbing component.
Solution Approach 2:
The patent uses a simple, inexpensive light-absorbing member that can be easily manufactured and installed, replacing the need for expensive complex housing treatments. The light-absorbing member is a straightforward component that achieves the desired light management effect without requiring costly manufacturing processes.
3Object-affected harmful factors
If the opening diameter of optical path sections is made smaller than the apparent diameter of collimator lenses, then back reflected light is inhibited, but the structural design becomes more specific
Solution Approach 1:
The patent applies local quality by creating a specific geometric relationship between the optical path section opening diameter and the collimator lens apparent diameter. This localized dimensional constraint ensures that stray light is blocked from entering the optical fiber while maintaining proper light transmission, achieving back reflected light inhibition through a simple geometric design rule rather than complex structural modifications.
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 design effectively inhibits the generation of back reflected light, reducing production costs and improving the optical component's performance by maintaining low return loss and minimizing stray light issues.
Implementation Method 1
An interference filter, in which a dielectric thin film is formed on a glass substrate, transmits light of a specific wavelength band and reflects light of other wavelength bands
Implementation Method 2
The input light Lin is emitted from the opening end (back end) 43 of the same optical fiber 41, and this emitted light subsequently enters the interference filter 3, as parallel beams L1, through the front collimator lens 51
Implementation Method 3
the interference filter 3 is tilted with respect to the optical axis; the shape of the filter housing section is formed so that a direction in which input light is reflected by the interference filter is toward the inside of the optical path section
Data Source
AI summary
An optical component including an interference filter which is less likely to generate back reflected light, where the filter is accommodated in a hollow cylindrical housing and is tilted with respect to the optical axis. The housing has front and back openings. First and second collimator lenses respectively face the front and back openings. The housing includes a filter housing section and first and second cylindrical optical path sections extending in the front-back direction respectively from the front and back openings to the filter housing section while maintaining the shape of each opening. The diameter of the opening of the first optical path section is smaller than the apparent diameter of the first collimator lens. When light is input from the front along the optical axis, light of prescribed wavelengths is output to the back. Light reflected by the filter travels toward the inside of the first optical path section.