Dual-channel phase-contrast spectral optical coherence tomography for simultaneously measuring axial and normal to B-scan off-axial displacements

- A dual-channel phase-contrast spectral OCT is built for measuring depth-resolved displacement fields.
- Axial and off-axial displacements acquired in real-time.
- Double-shot displacement measurement achieved by depth multiplexing.
- Normal to B-scan off-axial displacement can be measured.

A dual-channel phase-contrast spectral optical coherence tomography (DPC-SOCT) method is proposed for measuring axial and normal to B-scan off-axial displacements inside weakly scattering translucent materials. By employing a dual-channel observation structure with depth multiplexing, only one shot before and one shot after the object deformation are required for simultaneously measuring the displacements. To validate the method, a DPC-SOCT system was built and axial and normal to B-scan off-axial displacements inside polymer films were measured at 20 frames per second. The results suggest that the method can be used for investigating inner mechanical properties of materials under different loads. In the future, a method for all orthogonal measurement of displacement components will be developed.