But it is time-consuming and multiple-exposure is not applicable to dynamic scenes. One representative is image fusion where several images of the same scene are acquired while different parts of the object are focused on 3, 6. To overcome these limitations, a variety of techniques have been proposed over the past years. However, it leads to degrading of the optical power at the image plane and decrease of resolution. In general, the increase of DOF are associated with a reduction of the numerical aperture or the use of an optical power absorbing apodizer 5. Optical imaging with a large DOF is a longstanding goal with important applications in varied fields 1, 2, 3, 4. The parts of the image that lie outside the DOF tend to be blurred and less sharp. The depth-of-field (DOF) of an imaging system refers to the range in the scene that will appear in focus. In this proof-of-concept, we experimentally demonstrated the single-shot imaging with larger DOF using a thin glass scattering diffuser in both a single-lens imaging system and a microscopic imaging system.

Then the large DOF image was recovered from a speckle pattern by deconvolution. For the reconstruction, a stack of point spread functions (PSFs) corresponding to different axial locations within a measurement range were superimposed to construct the stacked PSF. It proved the important role of the scattering diffuser in extending the DOF of imaging systems. The results of numerical simulation showed that more high-frequency components existed in the defocused OTF curve when the exit pupil of the imaging system exhibited a random phase modulation. The DOF characteristic of the imaging system with random phase modulation was analyzed based on the analytical model of ambiguity function as a polar display of the optical transfer function (OTF). In this paper we presented a simple but efficient method to extend the DOF of a diffraction-limited imaging system using a thin scattering diffuser.

Large depth of field (DOF) is a longstanding goal in optical imaging field.

Dynamic depth of field