Fresnel Incoherent Correlation Holography

A well-known incoherent digital holography method is Fresnel incoherent correlation holography (FINCH). In FINCH, a light source divides into two beams of light that are then modified variably by two diffractive lenses with various focal distances and interfered with, creating a self-interference hologram. The hologram recreates the picture of the object at various depths via numerical backpropagation.

To create a complex hologram that can be used to reconstruct an object’s image without the twin image and bias terms, FINCH in the inline configuration needs at least three camera images with various phase shifts between the two interfering beams. In most cases, diffractive lenses are displayed using FINCH employing an active device, such as a spatial light modulator. Due to the phase mask employed in the original iteration of FINCH, produced by randomly multiplexing two diffractive lenses, there was significant reconstruction noise.

Polarization multiplexing was subsequently developed to reduce the reconstruction noise at the cost of considerable power loss. In this study, a brand-new computational approach dubbed transfer of amplitude into phase (TAP-GSA), which is based on the Gerchberg-Saxton algorithm (GSA), was created for Fresnel incoherent correlation holography to produce multiplexed phase masks with high light throughput and low reconstruction noise. In comparison to random multiplexing and polarization multiplexing, the new approach has a power efficiency boost of 150 and 200%, respectively, according to modeling and optical studies. In every test situation, the SNR of the suggested approach is higher than random multiplexing, although it is lower than polarization multiplexing.

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