Quantitative phase imaging based on holography: trends and new perspectives

Huang and Cao Light: Science & Applications (2024)13:145 https://doi.org/10.1038/s41377-024-01453-x REVIEW ARTICLE Official journal of the CIOMP 2047-7538 www.nature.com/lsa Open Access Quantitative phase imaging based on holography: trends and new perspectives 1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; Zhengzhong Huang1 and Liangcai Cao 1✉ Abstract In 1948, Dennis Gabor proposed the concept of holography, providing a pioneering solution to a quantitative description of the optical wavefront. After 75 years of development, holographic imaging has become a powerful tool for optical wavefront measurement and quantitative phase imaging. The emergence of this technology has given fresh energy to physics, biology, and materials science. Digital holography (DH) possesses the quantitative advantages of wide-field, non-contact, precise, and dynamic measurement capability for complex-waves. DH has unique capabilities for the propagation of optical fields by measuring light scattering with phase information. It offers quantitative visualization of the refractive index and thickness distribution of weak absorption samples, which plays a vital role in the pathophysiology of various diseases and the characterization of various materials. It provides a possibility to bridge the gap between the imaging and scattering disciplines. The propagation of wavefront is described by the complex amplitude. The complex-value in the complex-domain is reconstructed from the intensityvalue measurement by camera in the real-domain. Here, we regard the process of holographic recording and reconstruction as a transformation between complex-domain and real-domain, and discuss the mathematics and physical principles of reconstruction. We review the DH in underlying principles, technical approaches, and the breadth of applications. We conclude with emerging challenges and opportunities based on combining holographic imaging with other methodologies that expand the scope and utility of holographic imaging even further. The multidisciplinary nature brings technology and application experts together in label-free cell biology, analytical chemistry, clinical sciences, wavefront sensing, and semiconductor production. Introduction An accurate depiction of how waves spread in space and time is essential to the investigation of physical objects and their interactions with waves. In 1948, Dennis Gabor proposed the concept of holography1. After 75 years of development, holography has become a powerful tool for quantitative phase measurement. By using the reference wave, the sensor records the corresponding interference with the unknown object wave. The amplitude and phase of the object can be numerically reconstructed. Holographic recording and playback of waves have been used in numerous applications, including biological sample analysis, material representation, and material structure analysis2,3. Correspondence: Liangcai Cao () 1 Department of Precision Instrument, Tsinghua University, Beijing 100084, China Phase refers to measuring the optical path length shift at each point in the field of view introduced by a specimen. The light absorption value of various semitransparent objects is low because most of the light is scattering from the object, such as biological samples, resulting in a low-intensity-contrast image obtained by bright-field microscopy. The propagation of wavefront is described by the complex amplitude. Phase enables quantitative visualization of the inner structure or refractive index (RI) distribution of scattering samples with weak absorption. The main information can be reflected in the phase of the transmission wave due to the differences in the RI of cell liquid and external media. It is difficult for existing commercial cameras to achieve direct detection of phase in the visible light regime. To render the structures visible, one solution was to convert them into ‘amplitude objects’ using various stains or fluorescent tags with molecular specificity4,5. However, © The Author(s) 2024 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Huang and Cao Light: Science & Applications (2024)13:145 they are qualitative and sample-preparation-dependent, and the photobleaching and phototoxicity limit the fluorescent imaging of live cells. Furthermore, the use of exogenous labeling agents, such as fluorescent proteins or dyes, may alter the normal physiology of cells. The labeled cells cannot be re-injected into the human body. Another method is intrinsic contrast imaging occurred in the 1930s when Zernike invented a technique capable of imaging phase objects with high contrast and without the need for tagging6. The principle of Zernike’s phase contrast microscopy builds on Abbe’s understanding of imaging as an interference process7. To boost the contrast of the resulting interferogram and thus the image, Zernike added a phase shift of π/2. The additional phase shift places the scattered field in the antiphase with respect to the incident field. The resulting phase contrast field converts the phase into amplitude modulation. Phase contrast microscopes also balance the power of the two fields by attenuating the incident field. These simple modifications provides the microscope with the ability to visualize live, label-free cells and other weak absorption objects in rich detail. Gabor showed that recording the intensity of the light emerging from an object at an out-of-focus plane incorporates both amplitude and phase information about the field at the image plane. After the publication of holography by Dennis Gabor in 1948 which led to receiving a Nobel Prize in 1971, several important holography-related inventions occurred in the 1960s. E. Leith’s work on offaxis holography8 had a substantial impact in making holography a much more practical and popular discipline. The invention of the laser made holography even more practical. A. Lohmann’s introduction of computergenerated holograms used computers to numerically generate holograms to be printed and photographed for optical reconstruction2,9. In the late 1960s, there was the invention of digital holography (DH) by J. W. Goodman, who proposed usin (...truncated)