Fast Steering Mirror Calibration via Diffractive Beam Splitting
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Solution Overview
Problem
Traditional calibration methods for fast steering mirrors are time-consuming and prone to systematic errors due to environmental changes, and they struggle with achieving high precision and accuracy, especially for higher order corrections.
Innovation Solution
A calibration system utilizing a position sensing device with an interferometer and a diffractive optical element, such as a computer-generated hologram, to divide an input beam into multiple output beams that interact with the fast steering mirror, allowing for precise determination and adjustment of its tilt angle, thereby improving calibration accuracy and automation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement systems are used to calibrate fast steering mirrors, then calibration can be performed, but the process is time-consuming and prone to systematic errors from environmental changes
Solution Approach 1:
The patent replaces traditional mechanical measurement systems (theodolites, laser trackers) with an optical interferometry system. The interferometer uses light waves to measure mirror position and tilt angle, eliminating mechanical contact and associated systematic errors from environmental changes. This substitution enables faster, more precise calibration without mechanical limitations.
Solution Approach 2:
The patent introduces a diffractive optical element as an intermediary between the interferometer and the fast steering mirror. This element divides the laser beam into multiple beams that illuminate different portions of the mirror surface simultaneously, enabling comprehensive calibration of the entire mirror surface and improving both speed and accuracy.
2Extent of automation
If a theodolite is used to calibrate angular travel, then automation is achieved, but measurement resolution and range compete against each other, limiting the required calibration quality
Solution Approach 1:
The patent segments the calibration process by dividing the laser beam into multiple independent measurement beams using the diffractive optical element. Each beam measures a different angular portion of the mirror's travel range simultaneously, achieving both high resolution for each segment and comprehensive coverage of the full angular range, thereby resolving the trade-off between resolution and range.
3Manufacturing precision
If traditional measurement systems are used for higher order corrections, then calibration can be performed, but the large number of measurements required makes the process time-consuming
Solution Approach 1:
The patent enables continuous calibration by having the interferometer continuously track the mirror position while the diffractive optical element continuously provides multiple measurement beams across the mirror surface. This continuous simultaneous measurement of multiple points eliminates the need for sequential measurements, dramatically increasing productivity while maintaining high precision for higher order corrections.
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 system enables high-precision, automated calibration of fast steering mirrors, reducing the impact of environmental changes and improving measurement resolution and range, making it suitable for higher order corrections.
Implementation Method 1
The calibration system includes an interferometer configured to generate light
Implementation Method 2
a diffractive optical element, positioned between the position sensing device and the fast steering mirror, the diffractive optical element being configured to divide the input beam into a plurality of output beams
Implementation Method 3
the fast steering mirror includes a reflective surface, and is configured to manipulate the reflective surface to control a direction of the reflection of electromagnetic radiation off of the reflective surface
Data Source
Figure 1A~2A
Figure 2B~3A
Figure 3B
AI summary
A calibration system for calibrating a tilt angle of the fast steering mirror includes a position sensing device configured to generate a beam of electromagnetic radiation, and a diffractive optical element, positioned between the position sensing device and the fast steering mirror, the diffractive optical element being configured to divide the input beam into a plurality of output beams directed to the fast steering mirror. The position sensing device is configured to determine a tilt angle of the fast steering mirror. A method to calibrate a tilt angle of the fast steering mirror is further disclosed.