NV Diamond Fluorescence Reflector for Fiber Magnetometer Sensitivity
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Solution Overview
Problem
Existing NV diamond-based magnetometers suffer from low collection efficiency due to the high refractive index of diamonds, which limits their sensitivity for high-precision magnetometry, especially when coupled with optical fibers.
Innovation Solution
A sensor device is designed with a nitrogen-vacancy diamond source of fluorescence, utilizing a reflector to enhance collection efficiency by reflecting fluorescence towards a collector, and optionally using separate fibers for excitation and collection, along with a reflective coating and solid-immersion lenses to improve light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical fiber is used to excite and collect fluorescence from an NV diamond crystal, then the device can operate in challenging environments, but the collection efficiency becomes very low (less than 0.1%) due to the high refractive index of diamond
Solution Approach 1:
The patent introduces an optical fiber as an intermediary element that serves dual purposes: delivering excitation light to the diamond crystal and collecting the emitted fluorescence. This intermediary approach enables operation in challenging environments while the patent subsequently addresses the efficiency limitation through additional optical components.
Solution Approach 2:
The patent changes the optical parameters of the system by introducing a reflector with specific geometric parameters (conical shape, opening angle) and optical properties (reflectivity, coating material) to enhance the collection efficiency. This parameter optimization allows the system to overcome the inherent efficiency limitation of direct fiber coupling to diamond.
2Measurement precision
If a high numerical aperture air objective is used to collect fluorescence, then more photons can be collected, but the collection efficiency remains low (around 4%) and the system requires precise and stable alignment
Solution Approach 1:
The patent extracts the alignment complexity from the system by replacing the microscope objective with a fiber-based configuration combined with a reflector. This removes the need for precise alignment between the objective and diamond crystal, while the reflector ensures efficient photon collection without stringent alignment requirements.
Solution Approach 2:
The patent employs a conical reflector with a curved surface that is optimized to collect fluorescence photons from the diamond crystal and redirect them toward the optical fiber. The curved geometry of the reflector enhances collection efficiency by capturing photons from a wider angular range without requiring precise alignment.
3Device complexity
If the NV centers red fluorescence is coupled directly to fiber, then the setup is simplified, but the collection efficiency worsens to less than 0.1%
Solution Approach 1:
The patent merges the excitation and collection functions into a single optical fiber, maintaining setup simplicity. Additionally, it combines the fiber coupling approach with a reflector structure, creating a hybrid system that preserves the simplicity of direct fiber coupling while dramatically improving collection efficiency through the reflective enhancement.
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 significantly enhances collection efficiency, allowing for higher sensitivity and reduced power requirements, making it suitable for industrial applications with improved magnetic field detection capabilities.
Implementation Method 1
A sensor device comprising an excitation light source configured to provide excitation light; a source of fluorescence wherein said fluorescence is function of a physical phenomenon to be sensed and wherein said fluorescence is generated in response to an excitation provided by said excitation light source
Implementation Method 2
a reflector placed around said source of fluorescence to reflect said fluorescence towards said collector
Implementation Method 3
said collector is a first optical fiber. said first optical fiber is arranged to channel said excitation light to said nitrogen-vacancy diamond
Data Source
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AI summary
A sensor device is described. The sensor device comprises a source of fluorescence (1201, 1202, 1301, 1302), wherein said fluorescence is function of a physical phenomenon to be sensed and wherein said fluorescence is generated in response to an excitation provided by a source of excitation; a collector (1203, 1303) for collecting said fluorescence; a reflector (1210, 1310) placed around said source of fluorescence to reflect said fluorescence towards said collector, wherein said reflector is provided with an opening at its vertex, the source of fluorescence being arranged within said reflector to sense said physical phenomenon through said opening. A magnetometer comprising said sensor device is also disclosed.