Laser Beam Power Meter With Diffuser Sampling and Light Rejection
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Solution Overview
Problem
Current laser power measurement systems in remote charging systems are not reliable over long periods due to sensitivity to beam shape changes, wavelength variations, dust accumulation, and external illumination, requiring frequent recalibration.
Innovation Solution
A power measurement system with a detector positioned near the exit aperture of the laser, using a beam splitter to direct a minor part of the laser beam to a diffuser and detector, while absorbing external light, and employing a diffuser to ensure uniform sampling of the beam profile, reducing sensitivity to beam shape and wavelength changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a photodiode is used to measure back-reflection from a lens, then power efficiency is improved, but measurement reliability deteriorates due to sensitivity to lens misalignment, dust, wavelength changes, and external illumination
Solution Approach 1:
The system separates the measurement function from the main optical path by using a dedicated beam sampler positioned at a specific location to extract a portion of the beam for measurement, while the main beam continues to the receiver. This segmentation allows the measurement system to be optimized independently for reliability without affecting the main power transmission efficiency.
Solution Approach 2:
A beam sampler acts as an intermediary element that extracts a sample of the laser beam for measurement purposes without significantly interfering with the main beam. The beam sampler is positioned and angled to capture a portion of the beam while allowing the majority to pass through to the receiver, thus mediating between the measurement requirement and the power transmission requirement.
2Device complexity
If a leaking mirror is used to direct the beam towards a single photodiode, then device complexity is reduced, but measurement precision deteriorates due to susceptibility to dust, misalignment, and beam shape changes
Solution Approach 1:
The system transitions from a single-point measurement approach to a distributed measurement approach by using an array of photodiodes positioned at different locations. This dimensional change allows the system to capture beam profile information and maintain measurement precision even when the beam shape changes or when there is minor misalignment, as multiple measurement points provide redundancy and spatial information.
3Ease of operation
If the detector is positioned to face the exit aperture for easy alignment, then ease of operation is improved, but measurement reliability deteriorates due to sensitivity to external illumination
Solution Approach 1:
The system applies local quality by creating a spatially selective measurement configuration where the beam sampler and photodiode array are positioned to receive light from a specific direction (the laser beam) while blocking or filtering light from other directions (external illumination). The beam sampler is angled and positioned so that only the reflected laser beam reaches the detectors, giving the measurement system directional sensitivity that rejects external light sources.
4Measurement precision
If frequent recalibration is performed to maintain measurement accuracy, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system implements self-service through the use of a beam sampler and photodiode array configuration that passively maintains measurement accuracy over time. The geometric relationship between the beam sampler, diffuser, and detector array creates a measurement geometry that is inherently insensitive to beam shape changes and alignment drift, allowing the system to maintain precision without requiring frequent active recalibration or intervention.
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
Provides accurate and reliable power measurement over extended periods without recalibration, maintaining safety by minimizing interference from external light and beam profile variations.
Implementation Method 1
a beam splitter configured to transmit a major part of the laser beam through the exit aperture, and to reflect a minor part of the laser beam
Implementation Method 2
a diffuser element positioned such that the reflected minor part of the laser beam impinges thereon
Implementation Method 3
an absorber element positioned such that that part of any light entering the enclosure through the exit aperture and reflected by the beam splitter, impinges on the absorber element, and is essentially absorbed
Implementation Method 4
at least one detector element in optical communication with the diffuser element, the detector element providing a signal in response to the diffused light of the minor part of the laser beam impinging thereon
Data Source
AI summary
A system for measuring the power of a laser beam, comprising an essentially opaque enclosure, from which the laser beam is directed through an exit aperture. The enclosure contains a beam splitter configured to transmit a major part of the laser beam through the exit aperture, and to reflect a minor part of the laser beam; a diffuser element positioned such that the reflected minor part of the laser beam impinges thereon; at least one detector element in optical communication with the diffuser element, the detector element providing a signal in response to the diffused light of the minor part of the laser beam impinging thereon; and an absorber element positioned such that that part of any light entering the enclosure through the exit aperture and reflected by the beam splitter, impinges on the absorber element, and is essentially absorbed.