Nano-radian Angle Measurement with Drift Feedback Control
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Solution Overview
Problem
Traditional auto-collimation technology faces challenges in achieving nano-radian-order high angle resolution and stability due to limitations in focal length and light source drift, which restricts the measurement range and precision.
Innovation Solution
A high-stability nano-radian-order angle measuring method and device utilizing a four-quadrant position detector for real-time drift value feedback and steering mirrors for closed-loop control, combined with LED light sources and multi-slit diaphragms, to improve light source stability and angle resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal length of the collimation lens is increased to improve angle resolution, then the limit angle resolution is improved, but the measuring range is proportionally reduced
Solution Approach 1:
The patent segments the optical path into multiple sections with different focal lengths. The system uses a first collimation lens with focal length f1 for a first measuring range and a second collimation lens with focal length f2 for a second measuring range. This allows the system to achieve high resolution for small angles while maintaining a wide measuring range by switching between different optical configurations.
Solution Approach 2:
The patent implements dynamic switching between different collimation lenses based on the measuring range requirements. The system can adaptively select the appropriate focal length configuration, transitioning from a short focal length setup for wide-angle measurement to a long focal length setup for high-resolution small-angle measurement, thereby resolving the contradiction between resolution and measuring range.
2Adaptability or versatility
If the effective measurement area of the sensor is increased to improve measuring range, then the measuring range is improved, but the limit displacement resolution decreases
Solution Approach 1:
The patent segments the measurement function across multiple sensors with different effective areas. The first sensor has a first effective measurement area optimized for one measuring range, while the second sensor has a second effective measurement area optimized for another measuring range. This segmentation allows each sensor to operate at its optimal resolution while collectively providing a wide measuring range.
Solution Approach 2:
The patent creates a multi-functional measurement system where different sensors serve different measurement purposes. The system can selectively use different sensor configurations depending on the required measuring range, with each sensor optimized for specific measurement conditions, thereby achieving both wide range and high resolution without compromise.
3Device complexity
If traditional auto-collimation technology is used, then the device structure is simple, but the measurement stability is low due to light source drift
Solution Approach 1:
The patent introduces a feedback mechanism where a position detector continuously monitors the position of the light spot and provides feedback signals to adjust the light source position or detector position accordingly. This active compensation for light source drift significantly improves measurement stability while maintaining reasonable device complexity through automated correction.
Solution Approach 2:
The patent replaces passive mechanical stability reliance with active optical-electrical compensation systems. Instead of depending solely on mechanical rigidity and alignment, the system uses optical detection and electronic feedback to dynamically compensate for drift, achieving higher stability without proportionally increasing mechanical complexity.
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 method achieves nano-radian-order angle resolution in a 300 arc-second measuring range with enhanced stability, breaking the resolution-range limitations of traditional auto-collimation systems.
Implementation Method 1
a four-quadrant position detector is used as a feedback detection module at a light source emitting end to perform real-time high-precision detection on the drift value of displacement drift and angle drift generated by light sources
Implementation Method 2
steering mirrors are used as feedback execution modules to perform real-time closed loop feedback control according to the measured drift value, and light spots emitted from the light sources are always controlled in the center position
Implementation Method 3
Light emitted by the first LED light source and the second LED light source is respectively collimated by the fourth convex lens and the fifth convex lens and is then parallelly incident upon the first multi-slit diaphragm and the second multi-slit diaphragm
Implementation Method 4
the parallel light beams are incident upon a reflecting surface of a measured object 5. Light beams reflected from the reflecting surface of the measured object 5 are acquired by the image sensor 3 for imaging
Data Source
AI summary
Disclosed is a high-stability nano-radian-order angle measuring method and device based on drift value feedback, belonging to the technical field of precision measurement and the field of optical engineering. The device consists of LED light sources, convex lenses, multi-slit diaphragms, beam splitters, deflecting mirrors, steering mirrors, a collimator objective set, linear array CCDs, a four-quadrant position detector and a plane mirror. The method includes: enabling two paths of measuring light beams to carry angle change information of a measured object, respectively forming respective images on two sensors, and calculating a pitch angle and a yaw angle of the measured object relative to an optical axis by using positions of the two images so as to achieve the detection capability on the angle change of the measured object. While a focal distance of the objective is greatly improved by using the collimator objective set, the linear array CCDs are used as sensors to improve a measuring range. Therefore, the technical advantage of nano-radian-order angle limit resolution is achieved under the condition of the same measuring range. The LED light sources, the convex lenses and the multi-slit diaphragms are used, and at the same time, drift value feedback is performed by using the four-quadrant position detector and the steering mirrors, and the system stability is improved to 10 nano-radian order, thus solving the problem of limitation of light beam drift value to limit resolution of an autocollimator. Additionally, a system device designed by the present disclosure has the technical advantages of small structure size, high measurement precision and high measurement frequency response.