Quantitative Phase Imaging in Biomedical Research

Quantitative phase imaging (QPI) is a vital optical technique that empowers high-resolution, label-free imaging of transparent and turbid biological specimens. In contrast to traditional methods that require staining, QPI uses phase shifts to deliver comprehensive quantitative data on cell morphology and dynamics, conserving the natural state of the sample. Its highly sensitive ability to facilitate the measurement of parameters such as cell thickness, refractive index and dry mass proves that it as an ideal technique for live-cell imaging and in the field of biomedical research and diagnosis. This chapter delivers a complete outline of the fundamental mechanisms of QPI, including both interferometric and non-interferometric methods. It explores significant interferometric techniques such as digital holographic microscopy, spectral modulation interferometry, phase shifting interferometry and common-path interferometry, summarising their working principles, advantages and applications in various biomedical areas. Also, this chapter explains 2D and 3D QPI, where 2D QPI is for speedy surface examination and 3D QPI is for thorough volumetric imaging of cellular assemblies. Additionally, this chapter discusses recent developments in QPI, which have heightened the stability and sensitivity of QPI techniques by enhancing the precision in biomedical research.