Beam Angle Measurement With Active Tracking and Split Sensors
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Solution Overview
Problem
Existing methods for measuring the beam angle of a light beam, such as using quadrant detectors, are limited by small measurement ranges and sensitivity to lateral displacement, leading to inaccurate measurements and inefficient use of light beam power.
Innovation Solution
A control device that actively tracks the light beam to maintain its position on a light intensity sensor assembly, using a beam splitting device like a pyramid-shaped prism to distribute light evenly across sensors and prevent gaps, allowing for accurate beam angle measurement over a wide range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a quadrant detector is used to measure beam angle, then measurement bandwidth is improved (up to GHz range), but measurement range is limited by the spot size on the detector
Solution Approach 1:
The patent implements active tracking of the light beam using a deflecting optic that dynamically adjusts its position or angle to keep the beam centered on the quadrant detector. This dynamic adjustment allows the system to maintain high measurement bandwidth while extending the measurement range to larger beam angle deviations, as the beam is continuously recentered rather than relying on a fixed large detector area.
2Adaptability or versatility
If an aperture diaphragm is used for beam expansion, then beam angle measurement range is increased, but measurement precision deteriorates due to loss of representativeness and sensitivity to lateral displacement
Solution Approach 1:
The patent introduces a deflecting optic as an intermediary element between the light beam and the quadrant detector. This intermediary actively compensates for beam position variations through feedback control, maintaining measurement precision while enabling a larger measurement range. The deflecting optic serves as a mediator that decouples the beam's lateral displacement from the measurement process, unlike the aperture diaphragm which directly causes sensitivity issues.
3Speed
If the light beam is focused to a small spot on the quadrant detector, then measurement bandwidth is improved, but measurement range is reduced as the beam easily drifts outside the detector
Solution Approach 1:
The patent employs a feedback control system where the quadrant detector continuously monitors the beam position, and this information is used to adjust the deflecting optic's position or angle. This closed-loop feedback mechanism maintains the beam centered on the detector, allowing the system to operate with a focused small spot (high bandwidth) while simultaneously achieving a large measurement range through active compensation of beam drift.
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
Enables accurate beam angle measurement over a large range with high bandwidth, avoiding measurement range limitations and light loss, while maintaining precision and stability.
Implementation Method 1
using a beam splitting device like a pyramid-shaped prism to distribute light evenly across sensors
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a device and to a method for measuring the beam angle of a light beam guided by a beam guiding optical unit. A device according to the invention comprises a light intensity sensor arrangement (20, 30, 40, 50, 60), a focusing unit (21, 31, 41) for focusing the light beam onto a predetermined location on the light intensity sensor arrangement, and a tracking unit (22, 32, 42), which, in the event of a change in the beam angle present upon entry into the device, tracks a relative position of the intensity center of gravity of the light beam with respect to a predetermined location on the light intensity sensor arrangement. The tracking unit (22, 32, 42) is configured to keep the relative position of the intensity center of gravity of the light beam constant with respect to the predetermined location on the light intensity sensor arrangement (20, 30, 40, 50, 60) to a predetermined maximum deviation, wherein said maximum deviation corresponds to half of the mean beam diameter when impinging on the light intensity sensor arrangement (20, 30, 40, 50, 60).