Autocollimator with Segmented Detectors for Wide Field High Resolution
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Solution Overview
Problem
Conventional autocollimators face a trade-off between measurement range, resolution, and speed, often resulting in reduced resolution and slow measurement rates when trying to achieve high-speed, wide-field angle measurements, which is critical for applications like calibrating steering mirror motions.
Innovation Solution
An optical system comprising a broadband light source, an autocollimator with polarizing beam splitters, a diffraction grating device, and line scan cameras that capture interference patterns to measure tilt over a large range with high resolution and speed, utilizing a two-dimensional camera and CMOS sensors for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the measurement range is increased to achieve wide field autocollimation, then the field of view is improved, but the resolution deteriorates
Solution Approach 1:
The system divides the detection function into two separate detectors: a 2-D array detector for capturing wide-field angle information and a linear array detector for high-resolution measurement. This segmentation allows each detector to be optimized for its specific function, resolving the contradiction between wide field of view and high resolution.
Solution Approach 2:
The invention transitions from using a single 2-D array detector to a combination of 2-D and 1-D detectors. The 2-D detector captures spatial distribution over a wide field, while the 1-D linear detector provides high-resolution measurements along one dimension, effectively adding a dimensional specialization that resolves the resolution-field of view tradeoff.
2Measurement precision
If the number of pixels is increased to improve resolution, then the measurement precision is improved, but the sample rate deteriorates
Solution Approach 1:
The detection task is segmented between two detectors with different pixel configurations. The linear array detector has fewer pixels optimized for high-speed sampling, while the 2-D array provides spatial context. This segmentation allows the system to achieve high resolution without requiring a prohibitively large number of pixels in the high-speed detector.
Solution Approach 2:
The 2-D array detector acts as an intermediary that captures the full spatial distribution of the beam, while the linear array detector performs high-speed sampling. The system processes information from both detectors together, allowing the linear detector to operate at high sample rates without sacrificing overall measurement resolution.
3Area of stationary object
If the measurement range is increased to capture large angle deviations, then the field of view is improved, but the measurement speed deteriorates
Solution Approach 1:
The system segments the measurement function so that the 2-D array detector handles wide-field angle capture while the linear array detector handles high-speed sampling. This allows the system to simultaneously achieve large measurement range and high sample rate, resolving the contradiction between these two parameters.
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 achieves a 20×15 degree field of view with 300 kHz sample rate and 100 nrad jitter resolution, enabling absolute accuracy and high-frequency information recovery at fast line scan sample rates, balancing range, resolution, and speed effectively.
Implementation Method 1
a broadband light source configured to generate a beam of electromagnetic radiation
Implementation Method 2
a first polarizing beam splitter configured to direct the beam of electromagnetic radiation to the target device and to receive the beam of electromagnetic radiation reflected off of the target device
Implementation Method 3
direct the beam of electromagnetic radiation to a diffraction grating device, return diffracted electromagnetic radiation from the diffraction grating device
Implementation Method 4
an image detector configured to measure a tilt of the target device based on a measurement of the beam of electromagnetic radiation reflected off of the target device
Implementation Method 5
at least one lens to focus electromagnetic radiation from the target device to the diffraction grating device
Implementation Method 6
the at least one line scan camera configured to measure an interference pattern of diffracted electromagnetic radiation from the second polarizing beam splitter and capture an image
Data Source
AI summary
An optical system includes a light source, a target device, an image detector, and an autocollimator that receives a beam of electromagnetic radiation from the light source, directs the beam to the target device, and directs the beam to the image detector. The autocollimator includes a first polarizing beam splitter that directs the beam to the target device and receives the beam reflected off of the target device, a second polarizing beam splitter that receives the beam from the first polarizing beam splitter, directs the beam to a diffraction grating device, returns diffracted electromagnetic radiation from the diffraction grating device to an array of detectors, and directs the diffractive electromagnetic radiation, a camera that measures an interference pattern of diffracted electromagnetic radiation from the second polarizing beam splitter and captures an image, and a lens assembly that focuses electromagnetic radiation from the target device to the diffraction grating device.