A high-precision phase retrieval algorithm based on the transport of intensity equation for multi-wavelength illumination is proposed. First of all, the traditional transport of intensity equation method is used to obtain the phase of a single wavelength, and the initial phase of different wavelengths is calculated according to the corresponding phase relationship between different wavelengths. Secondly, through the wavelength phase synthesis module, the phase of the object under multiple wavelengths is obtained. For the noise amplification problem introduced in the phase synthesis step, the phase unwrapping module is used to eliminate the noise level in the initial phase result and gradually reduce it to the noise level of two synthetic short wavelengths. Finally, the high-precision phase retrieval result is obtained. The experimental results verify the correctness and effectiveness of the proposed method.
In view of the limitation that the transport of intensity equation method can only be used at a single wavelength, we propose a binocular phase retrieval algorithm based on multiwavelength illumination. First, we solve for the corresponding single-phase results at different wavelengths and then calculate the surface height of the object by combining the obtained synthetic wavelengths and synthetic phases, in order to reconstruct the initial phase results at different wavelengths. To solve the problem of amplification of traditional noise and surface profile noise in the phase diagram in the phase synthesis step, we introduce a step-by-step noise reduction method that can reduce the noise in the initial phase results to the level for a single wavelength and finally obtain the corresponding high-precision phase results at different wavelengths. The intensity images collected by the proposed dual-microscope system verify the correctness and effectiveness of the algorithm.
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