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Interferenceless coded aperture correlation holography is a recently developed technique for indirect 3D imaging of objects without two-wave interference. In such systems, the intensity response to a point is first recorded by modulating the light diffracted from a point object by a pseudorandom coded phase mask (CPM). The object intensity response is recorded under identical conditions and with the same CPM by mounting an object at the same axial location as of the point object. The image of the object is reconstructed by a crosscorrelation between the above two responses. In the present study, the imaging capabilities of a system with partial apertures are demonstrated by synthesizing the CPM in the shape of a ring. The partial aperture system demonstrates 3D imaging capabilities with an area as low as 1.4% of the total aperture area, which is beyond the limits of a regular imaging system. These superior imaging capabilities of the new technique might be useful for imaging with ground and space telescopes.

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Imaging with an optical incoherent synthetic aperture (SA) means that the incoherent light from observed objects is processed over time from various points of view to obtain a resolution equivalent to single-shot imaging by the SA larger than the actual physical aperture. The operation of such systems has always been based on two-wave interference where the beams propagate through two separate channels. This limitation of two channels at a time is removed in the present study with the proposed SA where the two beams pass through the same single channel at any given time. The system is based on a newly developed self-interference technique named coded aperture correlation holography. At any given time, the recorded intensity is obtained from interference between two waves co-propagating through the same physical channel. One wave oriented in a particular polarization is modulated by a pseudorandom coded phase mask and the other one oriented orthogonally passes through an open subaperture. Both subapertures are multiplexed at the same physical window. The system is calibrated by a point spread hologram synthesized from the responses of a guide star. All the measurements are digitally processed to achieve a final image with a resolution higher than that obtained by the limited physical aperture. This unique configuration can offer alternatives for the current cumbersome systems composed of far apart optical channels in the large optical astronomical interferometers. Furthermore, the proposed concept paves the way to an SA system with a single less-expensive compact light collector in an incoherent optical regime that may be utilized for future ground-based or space telescopes.

Fresnel incoherent correlation holography (FINCH) is a self-interference incoherent digital holography technique. It possesses a higher lateral resolution than an equivalent incoherent imaging system. However, FINCH has lower axial resolution than the direct imaging systems with the same numerical aperture. A decade after the FINCH invention, a different incoherent holographic method named coded aperture correlation holography (COACH) was developed with improved axial resolution but with the same lateral resolution as direct imaging. In this study, we propose and demonstrate a variant of COACH called coded aperture with FINCH intensity responses (CAFIR) with an improved lateral resolution that is similar to the FINCH system while maintaining its high axial resolution similar to the direct imaging system. CAFIR is implemented with coded phase masks to generate an ensemble of quasi-randomly distributed FINCH-like responses. Point spread holograms and object holograms are recorded under identical conditions, and they are cross-correlated to obtain the image reconstruction. Imaging of a multiplane object is studied to compare the axial resolution of CAFIR with FINCH and direct imaging systems.