Interferenceless coded aperture correlation holography–a new technique for recording incoherent digital holograms without two-wave interference

Abstract

Recording digital holograms without wave interference simplifies the optical systems, increases their power efficiency and avoids complicated aligning procedures. We propose and demonstrate a new technique of digital hologram acquisition without two-wave interference. Incoherent light emitted from an object propagates through a random-like coded phase mask and recorded directly without interference by a digital camera. In the training stage of the system, a point spread hologram (PSH) is first recorded by modulating the light diffracted from a point object by the coded phase masks. At least two different masks should be used to record two different intensity distributions at all possible axial locations. The various recorded patterns at every axial location are superposed in the computer to obtain a complex valued PSH library cataloged to its axial location. Following the training stage, an object is placed within the axial boundaries of the PSH library and the light diffracted from the object is once again modulated by the same phase masks. The intensity patterns are recorded and superposed exactly as the PSH to yield a complex hologram of the object. The object information at any particular plane is reconstructed by a cross-correlation between the complex valued hologram and the appropriate element of the PSH library. The characteristics and the performance of the proposed system were compared with an equivalent regular imaging system.

Implementation of a speckle-correlation-based optical lever with extended dynamic range

“…A computational module based on a completely open source GNU Linux-GNU Octave is presented with assistive computational codes to use a low-cost web camera for scientific application. The presented codes are not limited to SC-OptLev but can be adapted for many digital holography applications, especially for correlation optical systems [26][27][28], where real-time processing of holograms and simultaneous monitoring of many planes of an object are required.…”

Single camera shot interferenceless coded aperture correlation holography

“…As a consequence, the GSA constraint to render a pure phase function at the Fourier sensor plane is satisfied accurately. Therefore, the background noise is lower in this case compared with the previous I-COACH [13], and the averaging technique with multiple camera shots can be avoided. Additional reduction of the camera shots can be achieved by use of two rather than three different CPMs.…”

“…The intensity patterns of the light diffracted by the object and modulated by the CPMs are sufficient to reconstruct the object if the impulse response recorded under identical conditions is known. The principle of interferenceless COACH (I-COACH) has been recently demonstrated [13].…”

“…In the previous I-COACH [13], the light diffracted from the object was modulated by a CPM (CPM1) synthesized using the Gerchberg-Saxton algorithm (GSA), and the corresponding intensity pattern I 1 was recorded. Under identical conditions but with different CPMs (CPM2 and CPM3), second and third intensity patterns, namely I 2 and I 3 , were recorded by second and third camera shots, respectively.…”

Incoherent Digital Holography: A Review

“…It is worth noting that a diffractive lens is not needed to separate wavelength information by using a holographic technique [67,82]. Moreover, a stack of the PSFs is obtained without interference of incoherent light, and interferenceless incoherent 3D imaging for a scattering object has been performed [83]. In a most recent development, single-shot COACH with space-division multiplexing [84] has been proposed and demonstrated.…”