LBW	Laser Beam Welding
VIS	Visible Spectrum (approx. 317–900 nm)
NIR	Near-Infrared Spectrum (approx. 900–1934 nm)
CT	Computed Tomography, used for pore volume analysis
PFO	Programmable Focusing Optics
ϕ	Inclination Angles
ΔY	PFO Y Translation
DoE	Design of Experiments
FFT	Fast Fourier Transform
PCA	Principal Component Analysis
LSTM	Long Short-Term Memory, a type of RNN used for time-series data
MSE	Mean Squared Error
Set0	Dataset collected at 5000 Hz with 200 μs integration time (VIS and NIR channels)
Set1	Dataset collected at 100,000 Hz with 10 μs integration time (back-reflection channels)
Wk	Window number k in a channel
D(Wi)	Signal data in window Wi
σ	Sigmoid activation function
⊙	Element-wise multiplication
PSD	Power Spectral Density (from FFT)
FRESH	Feature Extraction based on Scalable Hypothesis tests (Python package)
CNN	Convolutional Neural Network
SVM	Support Vector Machine
RMS	Root Mean Square
Ti	Time step index
Eigenvector (w)	Direction of maximum variance
Eigenvalue (Λ)	Variance explained by a principal component (in PCA)