Spectral Camera Control for Stationary Flight Imaging
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Solution Overview
Problem
Spectral images captured by push-broom systems using airplanes suffer from spatial distortion and limited adjustable spatial resolution and exposure time, making it difficult to achieve optimal image quality due to fixed airplane velocities and varying weather conditions.
Innovation Solution
A spectral camera control system equipped with a liquid crystal tunable filter is used in an aircraft capable of stationary flight, allowing for snapshot mode image capture and adjustable spatial resolution and exposure time, with exposure time recalculated based on angular velocity and SN ratio thresholds to prevent distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If push-broom system is used to capture spectral images, then spectral image data can be acquired, but spatial distortion and deviation occur when airplane undergoes disturbance
Solution Approach 1:
The patent switches from a static push-broom scanning system to a dynamic snapshot capture system. The spectral camera captures the entire spectral range simultaneously in a single exposure, eliminating the temporal sequence of measurements. This dynamic approach freezes the spatial positions of all spectral bands at the same moment, preventing distortion from aircraft movement or vibration during data acquisition.
Solution Approach 2:
The invention uses a snapshot system that captures all spectral information at once, creating a complete copy of the spectral scene at a specific moment. This eliminates the need for sequential scanning and subsequent spatial registration of multiple scans, thereby avoiding cumulative distortion errors that occur in push-broom systems when the platform moves or vibrates.
2Measurement precision
If exposure time is increased to ensure sufficient SN ratio, then image quality improves, but spatial resolution becomes fixed and cannot be arbitrarily selected
Solution Approach 1:
The patent enables independent adjustment of exposure time and spatial resolution parameters. The snapshot system decouples these parameters, allowing the exposure time to be optimized for SN ratio without being constrained by spatial resolution requirements. Users can set exposure time based on lighting conditions and desired SN ratio, while spatial resolution is determined by the camera's field of view and sensor geometry, which can be independently configured.
3Reliability
If minimum velocity for safe flight is maintained, then airplane stability is ensured, but exposure time cannot be optimized for varying brightness conditions
Solution Approach 1:
The snapshot system allows the exposure time to be dynamically adjusted based on real-time lighting conditions while the aircraft maintains its minimum safe velocity. Unlike push-broom systems where exposure time is locked by the scanning speed requirement, the snapshot system can independently optimize exposure time for each capture, adapting to varying brightness conditions without compromising flight safety or image quality.
4Measurement precision
If narrow wavelength resolution of 20 nm or less is achieved, then spectral image quality improves, but device complexity increases with diffraction grating
Solution Approach 1:
The patent replaces the mechanical diffraction grating system with a snapshot-based temporal-multiplexing approach. Instead of using complex optical elements like diffraction gratings to achieve spectral resolution, the system captures the full spectral range simultaneously and processes it computationally. This substitution of mechanical/optical complexity with computational processing achieves narrow wavelength resolution without requiring complex optical components.
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
This approach enables arbitrary setting of spatial resolution and exposure time, reducing spatial distortion and improving image quality by adapting to changes in attitude and position, ensuring a high SN ratio across all wavelengths.
Implementation Method 1
a spectral camera provided with a liquid crystal tunable filter
Implementation Method 2
transmission wavelength of the liquid crystal tunable filter is switched
Data Source
AI summary
A spectral camera control device, being installed, along with a spectral camera provided with a liquid crystal tunable filter, in an aircraft capable of stationary flight. The spectral camera control device causes the spectral camera to capture a spectral image in a snapshot mode each time a transmission wavelength of the liquid crystal tunable filter is switched while the aircraft is in stationary flight, and the spectral camera control device causes a plurality of spectral images to be captured in succession at a same transmission wavelength when an SN ratio of the captured spectral image is less than a predetermined threshold.