Frequency Modulated X-ray Backscatter Depth Determination
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Solution Overview
Problem
Conventional X-ray backscatter systems lack the ability to determine depth information within a target without requiring high-cost and complex hardware such as multiple detectors, collimation, and coded apertures.
Innovation Solution
An X-ray backscatter imaging system utilizing frequency-modulated X-rays, where a local oscillator generates a frequency modulation signal to modulate both the bias current and voltage, producing X-rays that penetrate a target and are backscattered. A scintillating material converts the X-rays into photons, which are detected by a photodetector, and the phase delay information is processed to determine depth information using a discrete Fourier transform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional X-ray backscatter systems use fixed frequency X-rays, then the system is simple to operate, but depth information cannot be determined
Solution Approach 1:
The patent applies frequency modulation to the X-ray beam, changing the frequency parameter of the X-rays over time. This allows depth information to be extracted through frequency analysis of the backscattered signal, enabling depth determination without adding complex hardware like multiple detectors or collimators.
Solution Approach 2:
The patent replaces complex mechanical depth-determination systems (such as multiple detectors, collimators, and coded apertures) with a signal processing approach using frequency modulation and Fourier transform analysis. This substitutes physical complexity with electromagnetic signal manipulation and computational analysis.
2Loss of information
If multiple detectors, collimators, and coded apertures are used, then depth information can be determined, but the system becomes costly and complex
Solution Approach 1:
The patent extracts depth information from the temporal and frequency characteristics of the backscattered X-ray signal itself, rather than requiring additional hardware components. By analyzing the phase and frequency content of the modulated backscatter signal, depth data is obtained without removing or adding physical components to the basic detector system.
Solution Approach 2:
The patent uses frequency modulation to create multiple frequency components in the X-ray beam, where each frequency component corresponds to interactions at different depths. This allows a single detector to effectively capture information that would otherwise require multiple detectors operating at different geometries or energies.
3Measurement precision
If high power X-ray radiation is used, then better signal detection is achieved, but safety concerns increase
Solution Approach 1:
The patent uses periodic frequency modulation of the X-ray beam, switching between different frequency components in a controlled manner. This allows the system to accumulate signal information over multiple modulation cycles at lower power levels, achieving good signal-to-noise ratio without requiring continuous high-power radiation exposure.
Solution Approach 2:
The system uses feedback through frequency analysis of the backscattered signal to optimize the detection process. By analyzing the frequency spectrum of the returned signal, the system can identify depth-specific reflections and enhance those signals through selective processing, allowing lower overall radiation power while maintaining detection quality.
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 method allows for the determination of depth information within a target with reduced hardware complexity and cost, enhancing signal-to-noise ratio and providing detailed depth analysis of features, while being safer with low-power X-ray radiation.
Implementation Method 1
A scintillating material receives the X-ray radiation backscattered from the multiple depths within the target and generates photons corresponding to the backscattered X-ray radiation
Implementation Method 2
A photodetector receives the photons generated by the scintillating material and receives the frequency-modulated bias voltage and generates an analog output signal based thereon
Implementation Method 3
The X-ray radiation impinges upon and penetrates a target, and is backscattered from multiple depths within the target. The analog output signal contains phase delay information indicative of the various distances travelled by the X-rays backscattered from the various depths within the target
Data Source
AI summary
An X-ray backscatter imaging system uses frequency modulated X-rays to determine depth of features within a target. An X-ray source generates X-ray radiation modulated by a frequency-modulated bias current. The X-ray radiation impinges upon and is backscattered from multiple depths within the target. A scintillating material receives the backscattered X-rays and generates corresponding photons. A photodetector, having gain modulated by the frequency modulation signal from the local oscillator, receives the photons from the scintillating material and generates an analog output signal containing phase delay information indicative of the distance travelled by the X-rays backscattered from multiple depths within the target. The analog output signal is sampled by an analog-to-digital converter to create a digital output signal. A computer processor performs a discrete Fourier transform on the digital output signal to provide target depth information based on the phase delay information.