Comparison of common-path off-axis digital holography and transport of intensity equation in quantitative phase measurement

Abstract

The quantitative phase imaging methods based on digital holography (DH) and transport of intensity equation (TIE) are both popular high-resolution computational imaging techniques with broad applications. In contrast, the results of TIE often lack reliability, while those of DH are always regarded as the standard for phase measurements. Is DH more reliable and accurate than TIE in all cases? Here, we fully compare and analysis some common factors of conventional FFT-based TIE method and common-path off-axis DH method in quantitative phase measurements, such as the grayscale of recorded image (or hologram), effective measurement area, temporal stability, noise and the focal plane offset. By measuring some standard (microlens array and cake structure) and unknown samples (HT22 cells and fiber microstructure), the effects of different factors can be clearly quantified and illustrated. As a result, the DH method mainly suffers from the serious coherent noise and poor temporal stability, and the TIE method has a huge error when several factors are not selected properly, which explains its unreliability. Comparatively speaking, the TIE method can achieve better results with appropriate parameters.