NMR Imaging Device Using Periodic Pi Pulses for Dynamic Noise Isolation
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Solution Overview
Problem
NMR imaging using T2 Hahn echo is affected by static noise, making it difficult to distinguish substances based on their bonding state or external environment, particularly in semiconductor substrates where electron density differences are small.
Innovation Solution
Applying a π pulse at a predetermined interval to measure the generalized transverse relaxation time T2 L<, which isolates dynamic noise from static noise, allowing for clearer distinction of substances through NMR imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If T2 Hahn echo imaging is used, then the imaging method is simple and widely applicable, but substances with small electron density differences cannot be distinguished due to static noise interference
Solution Approach 1:
The patent applies periodic π pulses at predetermined intervals to the sample during NMR imaging. This periodic action modulates the spin system dynamics, causing the NMR signal to reflect both static and dynamic noise components. By analyzing the signal attenuation pattern over multiple periodic pulse applications, the method extracts T2L that contains dynamic noise information, enabling differentiation of substances with small electron density differences while maintaining practical applicability
Solution Approach 2:
The patent changes the measurement parameter from traditional T2 Hahn echo to T2L (generalized transverse relaxation time) by introducing periodic π pulses with specific intervals. This parameter change transforms the NMR signal characteristics, making it sensitive to dynamic noise components that vary with the pulse interval. The ability to adjust the pulse interval provides flexibility in optimizing the measurement for different materials and noise conditions
2Measurement precision
If multiple imaging methods are used to distinguish substances, then substance differentiation capability improves, but imaging time and measurement complexity increase
Solution Approach 1:
The T2L imaging method serves multiple functions: it provides substance differentiation capability similar to multiple imaging methods, while simultaneously being a single, unified imaging approach. The method can distinguish both static and dynamic noise components through the periodic pulse sequence, effectively combining the advantages of different imaging techniques into one versatile method that reduces total imaging time
Solution Approach 2:
The patent applies a series of π pulses at predetermined intervals before the actual measurement is complete. This preliminary action prepares the spin system in a controlled manner, allowing the extraction of dynamic noise information that would otherwise require separate specialized imaging sequences. The predetermined interval is optimized in advance to maximize information extraction efficiency
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
Enables the differentiation of substances that cannot be distinguished by traditional T2 Hahn echo imaging by isolating dynamic noise, improving the ability to image semiconductor substrates and potentially other materials with small electron density differences.
Implementation Method 1
Nuclear magnetic resonance (NMR) is a phenomenon that a resonance occurs between a magnetic field and an atomic nucleus when a nuclear spin that is precessing in the magnetic field is applied with a rotating magnetic field having the same frequency as a Larmor frequency of the precession
Implementation Method 2
the static magnetic field is applied in a center axis (Z axis) direction, so as to change the spin direction in an XY axis direction
Implementation Method 3
when a nuclear spin that is precessing in the magnetic field is applied with a rotating magnetic field having the same frequency as a Larmor frequency of the precession
Implementation Method 4
for the nuclear spin to return to an original state after changing the state due to the resonance are different depending on a situation of the nuclear spin
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In order to provide an NMR imaging device capable of distinguishing substances that cannot be distinguished by T 2 H , an NMR imaging device (1) according to this invention includes: a probe (3) capable of housing a sample in a static gradient magnetic field; an application portion (5) configured to apply a À pulse having a Larmor frequency corresponding to the static gradient magnetic field at a predetermined position of the sample to the sample in a multiplexed manner at a predetermined time interval; and an image processing portion (7) configured to determine a relaxation time based on a nuclear magnetic resonance signal of the sample, and perform imaging of the relaxation time.