Discontinuous wavelength-scanning interferometry with an unknown gapped spectrum

Depth-resolved wavelength-scanning interferometry (DRWSI) has emerged as a powerful topographic technique for simultaneously measuring multiple surfaces. Conventional DRWSI requires the laser to emit a continuous spectrum; however, ensuring this condition is often challenging. This Letter presents a discontinuous DRWSI measurement approach that can automatically predict the missing intensity within the gapped spectrum without requiring any prior knowledge. Therefore, the phase jitters caused by the discontinuities in wavelength scanning can be effectively removed, enabling high-quality reconstruction of the depth-resolved phase maps. Simulation demonstrated that the proposed approach can accurately restore the phase map even when the gap interval is 10 times larger than the entire wavelength-scanning range. Experimental results confirm the robustness of this approach for discontinuous DRWSI measurements under mode-hopping laser outputs. The contribution of this work can alleviate the stringent requirements for the diode laser output, enhancing the flexibility and practicality of DRWSI measurements.