PEAR-FINCH: A new breakthrough in 3D holographic imaging

A novel technological solution for improving the quality of 3D images was introduced in the article "Axial resolution post-processing engineering in Fresnel incoherent correlation holography" published in the Journal of Physics: Photonics by Shivasubramanian Gopinath, a doctoral student at the Institute of Physics. The University of Tartu supported the open-access publication of the article.

Three-dimensional (3D) imaging of tiny and complex biological structures is essential for modern microscopy and biomedical research. A powerful technique known as Fresnel Incoherent Correlation Holography (FINCH) has been widely used to capture 3D information using ordinary (incoherent) light, offering higher resolution and a longer depth of focus than conventional imaging systems. However, until now, both traditional microscopes and FINCH systems had a key limitation: once an image or hologram was recorded, the imaging properties were fixed. Researchers could not go back and adjust the depth of focus or other imaging characteristics after the experiment. To overcome this, we developed a new method called Post-Engineering of Axial Resolution in FINCH (PEAR-FINCH). Instead of relying on a single hologram, PEAR-FINCH records a library of holograms with different focal distance aberrations. These are then computationally combined to create a synthetic hologram that provides a much larger depth of focus.

What makes PEAR-FINCH unique?

• The depth of focus can be engineered after the hologram has already been recorded.
• A new two-step computational reconstruction maintains high image quality and signal-to-noise ratio.
• Demonstrated a five-fold increase in depth of focus compared to conventional FINCH.
• Works well under diffusive illumination, similar to real biological samples.

This level of post-recording flexibility has not been reported before and represents a new paradigm in holographic imaging. Our results show that PEAR-FINCH consistently outperforms both conventional direct imaging systems (DIS) and standard FINCH.

Why is PEAR-FINCH needed?
PEAR-FINCH makes 3D holographic microscopy more flexible, powerful, and practical for real-world biological and biomedical applications. It opens new possibilities for studying complex biological structures and challenging imaging environments, bringing us closer to more adaptable and intelligent microscopes.

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S. Gopinath, J. Rosen, and V. Anand, "Axial resolution post-processing engineering in Fresnel incoherent correlation holography," Journal of Physics: Photonics (2026). https://doi.org/10.1088/2515-7647/ae38ae