Hybrid Dual Wavelength Digital Holography Method Combining Beat Frequency and Constrained Underdetermined Equations

This paper proposes a hybrid dual-wavelength digital holography (DWDH) method. By combining the beat frequency with the constrained underdetermined equations, the proposed hybrid DWDH use the constrained underdetermined equations method to reconstruct the thickness beyond a synthetic wavelength, and use the beat frequency method to retrieve the thickness within the synthetic wavelength. This design of the proposed method can improve the execution efficiency of constrained underdetermined equation. Simulation results verify that this method can extend the measurement range beyond the synthetic wavelength and reduce the computational time when reconstructing high-thickness samples. Experimental results also demonstrate the validity of the proposed method. This method is suitable for scenarios that high methodic computation speed is required. It is also applicable in situations where the maximum sample thickness exceeds one synthetic wavelength but occupies a relatively small area, and high imaging speed is necessary.