Article

Purely numerical compensation for microscope objective phase curvature in digital holographic microscopy: influence of digital phase mask position.

Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut d'Optique Appliquée, Ch-1015 Lausanne, Switzerland.
Journal of the Optical Society of America A (Impact Factor: 1.45). 12/2006; 23(11):2944-53. DOI: 10.1364/JOSAA.23.002944
Source: PubMed

ABSTRACT Introducing a microscope objective in an interferometric setup induces a phase curvature on the resulting wavefront. In digital holography, the compensation of this curvature is often done by introducing an identical curvature in the reference arm and the hologram is then processed using a plane wave in the reconstruction. This physical compensation can be avoided, and several numerical methods exist to retrieve phase contrast images in which the microscope curvature is compensated. Usually, a digital array of complex numbers is introduced in the reconstruction process to perform this curvature correction. Different corrections are discussed in terms of their influence on the reconstructed image size and location in space. The results are presented according to two different expressions of the Fresnel transform, the single Fourier transform and convolution approaches, used to propagate the reconstructed wavefront from the hologram plane to the final image plane.

0 Bookmarks
 · 
70 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The tendency of particles to aggregate depends on particle-particle and particle-fluid interactions. These interactions can be characterized but it requires accurate 3D measurements of particle distributions. We introduce the application of an off-axis digital holographic microscopy for measuring distributions of dense micrometer (2 μm) particles in a liquid solution. We demonstrate that digital holographic microscopy is capable of recording the instantaneous 3D position of particles in a flow volume. A new reconstruction method that aids identification of particle images was used in this work. About 62% of the expected number of particles within the interrogated flow volume was detected. Based on the 3D position of individual particles, the tendency of particle to aggregate is investigated. Results show that relatively few particles (around 5–10 of a cohort of 1500) were aggregates. This number did not change significantly with time.
    Optics and Lasers in Engineering 05/2015; 68. · 1.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of non-telecentric imaging systems in quantitative phase digital holographic microscopy introduces strong inaccuracies. We show that even negligible errors in the radius and center of curvature of the remaining quadratic phase factor introduce big errors in the numerical phase measurements. The errors depend on the position of the object in the field-of-view. However, when a telecentric imaging system is utilized for the recording of the holograms, the hybrid imaging method shows shift-invariant behavior, and therefore accurate quantitative phase imaging can be performed.
    SPIE Sensing Technology + Applications; 06/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we present our results obtained using an interferometric technique to investigate a constant thickness sample, which presents inside regions with different values for the refractive index. The sample is prepared on a polycarbonate (PC) substrate. On its surface, some microstructures are imprinted using controlled values for temperature and forces, after we determined experimentally the value of the temperature for glass transition. These microstructures were then filled with an epoxy resin. Using the images acquired experimentally, we computed the phase shift map introduced by the sample in the optical path. It is proportional with the geometrical height of the microstructures and with the difference between the refractive indices of the polycarbonate and the epoxy resin. In this way, we find the phase shift profile inside of a transparent thin film of a sample with plane parallel surfaces.
    UPB Scientific Bulletin, Series A: Applied Mathematics and Physics 01/2014; 76(1):177-186. · 0.28 Impact Factor

Full-text (2 Sources)

Download
101 Downloads
Available from
Jun 6, 2014