"This work introduces two different optical configurations developed to inspect in a non-invasively form biological and engineering samples. The first configuration is an interferometer with a minimum of optical hardware to measure in transmission mode. It is denominated as a transmission digital holographic interferometer (t-DHI). It is applied to retrieve the optical phase from micrometric size semi-transparent biological samples. Our proposed t-DHI system avoids the drawback of this small field of view (FOV) and problematic hardware use when compared with digital holographic microscopy (DHM). The t-DHI setup is used to inspect pollen grains as proof of principle to found a correlation between their size and the phase information. The dimensions of each pollen grain are validated by processing their fluorescence image obtained with the aid of a confocal microscope. The second configuration introduced is a dual optical set up that simultaneously uses a digital holographic interferometer (DHI) and a Fourier domain optical coherence tomography (FD-OCT). These two independent modules inspect the external and internal optical phase information of composite materials when they undergo a compression load during a mechanical test. The sample under study is a composite material of poly-methyl-methacrylate (PMMA) reinforced with metallic microparticles of copper (Cu). Two sets of specimens with different dimensions are analyzed to compare their mechanical behavior when a home-made testing machine applies a controlled compression load force when both modules are continuously recording. Therefore, the surface and internal optical phases are correlated to the same compression value to have a full 3D displacement measurement."