Diamagnetic Photon Momentum Radiometer for Laser Power Measurement
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Solution Overview
Problem
Conventional technologies lack a simple and cost-effective method for measuring optical power of a laser based on determining radiation pressure from the laser light.
Innovation Solution
A gravity-enforced photon momentum radiometer is developed, utilizing a diamagnetic levitation force to levitate a shuttle with a mirror, where the laser light's momentum displaces the shuttle, and the position is restored by tilting a magnet array, allowing for closed-loop control and measurement of optical power without requiring accurate knowledge of the system's spring constant or environmental dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to measure optical power, then measurement can be performed, but the method is not simple and cost-effective
Solution Approach 1:
The patent replaces conventional electrical/electronic measurement systems with a mechanical-based diamagnetic levitation system. The optical power measurement is achieved through mechanical displacement of a levitated mirror by radiation pressure, which is then converted to an electrical signal. This substitution enables simple, cost-effective measurements while maintaining accuracy traceable to fundamental constants (mass, gravity, speed of light).
Solution Approach 2:
The diamagnetic levitation system uses the radiation pressure from the laser itself to drive the measurement. The laser light automatically exerts force on the mirror, causing displacement that is measured by the photodetector. This self-driven mechanism eliminates the need for external calibration standards or complex calibration procedures, making the system both simple and accurate.
2Measurement precision
If diamagnetic levitation is used to measure radiation pressure, then accurate optical power measurement is achieved, but device complexity increases
Solution Approach 1:
The patent uses diamagnetic levitation to create a contactless suspension system where the magnetic force counteracts gravity, holding the mirror assembly in equilibrium. This anti-weight mechanism eliminates mechanical friction and wear, enabling precise measurement of the small radiation pressure forces while simplifying the overall mechanical structure by removing traditional support bearings and mounting mechanisms.
Solution Approach 2:
The diamagnetic mirror assembly acts as an intermediary between the optical field (radiation pressure) and the measurement system (photodetector). The radiation pressure force is transferred to the mirror, which then moves and blocks the gate light proportionally. This intermediary converts the difficult-to-measure radiation pressure into an easily detectable optical signal, reducing system complexity.
3Measurement precision
If closed-loop control is implemented with tiltable platform, then measurement accuracy improves, but control system complexity increases
Solution Approach 1:
The patent implements a closed-loop feedback system where the photodetector continuously monitors the position of the diamagnetic mirror by detecting gate light blocking. This position information is fed back to a control system that adjusts the tiltable platform angle to maintain the mirror in a reference position. The feedback mechanism enables high measurement accuracy by compensating for disturbances and non-linearities in real-time.
Solution Approach 2:
The tiltable platform provides dynamic adjustment capability to the magnetic array orientation, allowing the system to adapt to varying optical power levels and maintain optimal measurement conditions. This dynamic control enables the system to handle a wide range of input powers while maintaining accuracy, without requiring multiple fixed-setup measurement systems.
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 approach provides a low-cost, accurate method for measuring laser power, with an expanded uncertainty of 1.8% and a noise equivalent power of 30 mW/√Hz, traceable to the mass of the levitating system and gravitational acceleration, enabling precise measurement of optical power across a range of values.
Implementation Method 1
a magnetic array that produces a diamagnetic levitation force; a diamagnetic shuttle disposed proximate to the magnetic array such that the diamagnetic shuttle is in communication with the magnetic array and subjected to the diamagnetic levitation force from the magnetic array whereby the diamagnetic shuttle levitates above the magnetic array
Implementation Method 2
a mirror disposed on the diamagnetic shuttle and that receives an incident optical force from the laser light and moves, in response to receipt of the incident optical force, the diamagnetic shuttle in a direction of propagation of the laser light
Implementation Method 3
a photogate comprising an optical source that transmits gate light and a detector that detects the gate light from the photogate and produces a detector signal based on the amount of the gate light detected
Data Source
AI summary
A gravity-enforced photon momentum radiometer incudes: a magnetic array; a diamagnetic shuttle that levitates above the magnetic array; a mirror on the diamagnetic shuttle that receives laser light and moves the diamagnetic shuttle due to the optical force; a tiltable platform for the magnetic array; a photogate producing gate light that can be blocked by a photo interrupter and that produces a detector signal that provides a position of the diamagnetic shuttle relative to the tiltable platform for determining a position of the diamagnetic shuttle relative to the photogate.