  Inline Coherent Imaging (ICI) is a reliable method for real-time monitoring
of various laser processes, including keyhole welding, additive manufacturing,
and micromachining. However, the axial resolution is limited to greater than 2
{\mu}m making ICI unsuitable for monitoring submicron processes. Advancements
in Quantum Optical Coherence Tomography (QOCT), which uses a Hong-Ou-Mandel
(HOM) interferometer, has the potential to address this issue by achieving
better than 1 {\mu}m depth resolution. While time-resolved QOCT is slow,
Fourier domain QOCT (FD-QOCT) overcomes this limitation, enabling submicron
scale real-time process monitoring. Here we review the fundamentals of FD-QOCT
and QOCT and propose a Quantum Inline Coherent Imaging system based on FD-QOCT.
Using frequency entangled sources available today the system has a theoretical
resolution of 0.17 microns, making it suitable for submicron real-time process
monitoring.
