In this paper, we address quantitative phase imaging of hard-to-reach objects using conventional endoscopic probes. We present a scheme of digital holographic module compatible with commercially available rigid rod-lens endoscopes. In this scheme, a reference beam is obtained using a single-mode optical fiber. The module is a quite simple two-lens system located behind the endoscope eyepiece. It allows the registration of Fourier holograms as well as conventional imaging mode.
We propose to use an acousto-optic tunable image filtration to implement spectral and phase measurements in nearcommon-path interferometric module based on Michelson interferometer with artificial reference light source. In such two-beam interferometer, reference beam is formed via spatial filtration from one of the light beams. The module may be placed at the output of the imaging device for obtaining wideband images of the inspected object, such as, for example, camera port of transmitted light microscope. Acousto-optical tunable imaging filter is necessary to enable spectral measurements as well as quantitative phase retrieval.