Phase retrieval is to recover the original phase information by using the intensity information obtained from observation [1-2] which including interference technique and non-interference technique. Phase retrieval based on the transport of intensity equation (TIE) is an important non-interference technique. Compared with the traditional interference approaches, it does not need to rely on the superposition of two highly coherent lights, complicated interference devices or strict requirements on the stability of the environment . This method requires only a minimum of two intensity measurements at closely spaced planes for quantitative phase retrieval. Thus, this technology extends applications to microscopy, X-ray phase contrast imaging, diffractive optics and optical measurement [5-7]. The conventional TIE method requires moving the object or the CCD to achieve the acquisition of the intensity image, which inevitably introduces errors in the acquired image data. To this end, a method using the liquid crystal on silicon (LCoS) as tunable-lens for phase retrieval was proposed by Cheng Hong . Different defocus images could be formed by changing the phase distribution loaded in the LCoS, which could avoid the errors caused by the mechanical movement. However, the introduction of the LCoS zoom lens in the experiment has an effect on the acquisition of the intensity image and increases the difficulty of the experimental operation. Zuo et al. proposed a method called SQPM, two laterally separated images from different focal planes could be obtained simultaneously by a single camera exposure, yet the accurate registration of the two experimental images was performed necessarily.
Angular spectrum iterative algorithm is another classic non-interference phase retrieval algorithm. This algorithm has the characteristics of high calculation accuracy and strong adaptability, but its convergence speed is slow and it depends on the initial solution so it tends to converge to the local minimum. Guo Junhu et al. combine TIE with iterative algorithm to improve this shortcoming . But this algorithm still needs to move the object or camera mechanically when acquiring the intensity.
At the same time, the above mentioned methods are all carried out under monochromatic light. In order to apply a light source with multi-wavelength continuous spectrum to retrieval phase, some numerical methods were designed. Cheng Hong et al.  proposed a phase extraction algorithm in lens-based wave propagation model to relieve the effects of phase modulation, which only need to calculate three color components of the phase from the acquired intensity images, then synthesized the final phase. However, this method is the processing of intensity images after sampling, not the application of multi-wavelength in the real sense. Besides, Laura Waller et al.  proposed using a white light and a Bayer color camera to acquire a color image at a fixed position, then three monochrome images of the RGB channel are obtained from captured color image and further processed to get the phase result. But this technology requires a specific color camera and reduces the resolution of the recovered phase.
Here, a chromatic dispersion- hybrid phase retrieval method (CD-HPR) in single-lens system is proposed. It is ensured that the intensity images of the object with different defocus distance can be obtained in the same plane without moving the object or the CCD, the error caused by the mechanical movement in the conventional method and resolution reduction problem are avoided. At the same time, the application of TIE can be extended to multi-wavelength sources, especially for the complex phase reconstruction applied in natural light scene in the future. The CD-HPR method is applied to single-lens system in this paper, and the relevant experimental results are given.