Magnetic Field Sensor Head with GI Fiber Beam Expansion
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Solution Overview
Problem
Existing magnetic field sensor heads face challenges in manufacturing ease and detection sensitivity, particularly due to troublesome optical alignment between optical fibers and GRIN lenses.
Innovation Solution
A magnetic field sensor head design featuring a GI fiber optically connected to an optical fiber, a magnetic film, a reflection film, and a support member, with the cladding diameter of the GI fiber matching that of the optical fiber, forming a square columnar rod-shaped member, and using a rare earth iron garnet magnetic film for high detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a GRIN lens is arranged between the optical fiber and magnetic film to enlarge the light incident region, then detection sensitivity is improved, but optical alignment becomes troublesome and manufacturing is not easy
Solution Approach 1:
A beam expanding plate is introduced as an intermediary component between the optical fiber and magnetic film. This plate expands the beam diameter of light from the optical fiber to match the larger dimensions of the magnetic film, enabling improved detection sensitivity while maintaining simple optical alignment and easy manufacturing through standardized component interfaces
2Measurement precision
If the magnetic film size is enlarged to increase light incident region, then detection sensitivity is improved, but optical alignment with standard optical fiber becomes difficult
Solution Approach 1:
The beam expanding plate transforms the optical geometry by expanding the beam diameter in the transverse dimension. This allows the magnetic film to have larger dimensions (e.g., 2mm x 2mm) while the optical fiber maintains its standard small core diameter, achieving both improved detection sensitivity and precise optical alignment through dimensional transformation
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 design facilitates easy manufacturing and enhances detection sensitivity by broadening the luminous flux, simplifying optical alignment, and improving detection performance.
Implementation Method 1
a magnetic field sensor head using a polarization maintaining fiber is known... a GRIN lens is arranged between an optical fiber and magnetic film... to enlarge the region of the magnetic film upon which light is incident
Implementation Method 2
a magnetic field sensor head is described in Japanese Unexamined Patent Publication No. 2020-126006 in which a second polarization maintaining fiber with a fast axis and a slow axis inclined by 45 degrees with respect to the fast axis and slow axis of a first polarization maintaining fiber is arranged between a polarization maintaining fiber and a Faraday rotator comprised of a granular film
Data Source
AI summary
A magnetic field sensor head includes an optical fiber, a GI fiber whose one end is optically connected to the optical fiber, a magnetic film joined to the other end of the GI fiber, a reflection film joined to a surface of the magnetic film opposite to a surface joined to the magnetic film, and a support member joined to a surface of the reflection film opposite to the surface joined to the magnetic film.