Method for identifying chemical and structural variations through terahertz time-domain spectroscopy

A method for identifying chemical and structural irregularities in a substrate, comprising:

• providing a sample comprising a plurality of points and having chemical or structural variations;
• providing a terahertz scanner comprising:
• at least one terahertz source generating a terahertz beam along a terahertz beam path, and
• at least one terahertz detector, wherein
• the terahertz scanner produces a characteristic signal when the terahertz beam is detected by the at least one terahertz detector after interacting with a point of the plurality of points of the sample;
• and
• the terahertz scanner produces a reference signal when the terahertz beam is not intercepted by the sample;
• obtaining a characteristic signal and a reference signals for at least one point of the plurality of points of the sample;
• extracting one or more characteristic features from a characteristic data set afforded by the characteristic signal, and extracting one or more corresponding reference features from a reference data set afforded by the reference signal;
• wherein at least one of the characteristic features and the corresponding reference features are selected from a list consisting of:
• peak intensity, average intensity, delay, pulse width, spectral power, phase of the characteristic signals, and any combination thereof;
• analyzing the characteristic features and the corresponding reference features using a machine learning data analysis model to find chemical and or structural information about the sample;
• and
• recognizing irregularities in or differences between the characteristic features and the corresponding reference features to identify the chemical or structural variations in the sample.