Wide Field Astropography Imaging Device Sliding Stack SNR
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Solution Overview
Problem
Astronomical imaging instruments face limitations in capturing the entirety of large celestial objects due to their intrinsic field constraints, necessitating techniques to expand the object field and improve signal-to-noise ratio (SNR).
Innovation Solution
The method employs a sliding stack technique, where each raw image is used to update an extended image, achieving a high overlap rate between successive images, typically greater than 85%, to enhance the SNR. This approach involves summing point values from both the new raw image and the previous extended image for corresponding points, effectively creating a mosaic of stacks with improved SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the intrinsic field of the instrument is increased to capture larger object fields, then the field of view is improved, but the optical system characteristics must be changed which increases device complexity
Solution Approach 1:
The patent divides the large field of view into multiple smaller intrinsic fields by capturing a sequence of images with the optical system positioned at different locations along a field path. Each image covers a portion of the total field, and these segmented images are then registered and combined to form the complete wide-field image, avoiding the need to change optical system characteristics.
Solution Approach 2:
The patent extends the imaging capability from a single two-dimensional detector plane to a three-dimensional space-time volume by moving the optical system along a field path through space and time. This allows the instrument to capture a much larger effective field of view by sampling different spatial positions sequentially, then reconstructing the complete field through image registration.
2Measurement precision
If traditional stack mosaicking is used to improve SNR, then image quality is improved, but the SNR increase is limited compared to the potential improvement
Solution Approach 1:
The patent employs a dynamic sliding stack approach where the stack of images is continuously updated as new images are acquired along the field path. Unlike static stacking that processes fixed sets of images, this dynamic approach allows the stack to adapt and grow continuously, incorporating new information from each acquired image and maintaining optimal SNR improvement throughout the observation sequence.
Solution Approach 2:
The patent performs preliminary image registration and stacking operations incrementally as images are acquired, rather than waiting to process all images at once. This allows early SNR improvement to be achieved and utilized, while subsequent images continue to build upon and enhance the already-processed data, maximizing the productive use of acquisition time.
Data Source
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AI summary
According to one aspect, one subject of the present description is a wide-field astronomical imaging device for imaging a scene, comprising: an optical system (101) comprising an optical axis (270) that is rotatable about at least two axes of rotation; a two-dimensional optical detector (102) configured to acquire raw images of segments of said scene with said optical system (101); a control unit (104) configured to control said optical axis (270) and to acquire, over time, a plurality of raw images defining a plurality of different segments of said scene, two successive segments of said plurality of segments having at least one common portion, said plurality of raw images respectively corresponding to a plurality of positions of said optical axis; and a processing unit (105) configured to compute, for each raw image acquired, an extended image (240) of larger size than an extended image (210) computed beforehand.