Diffraction tomography for biological cells imaging using digital holographic microscopy

Many biological objects are mainly transparent and weakly scattering, thus a promising (and already widely used) way of imaging them consists in considering optical refractive index variations. The method proposed here permits 3D imaging of the refractive index distribution with a tomographic approach. Usually, the classical Radon transform does not sufficiently take into account the physical interaction between light and biological cells, therefore diffraction has to be considered. Diffraction tomography is a method that permits 3D reconstruction of the refractive index, using many captures of the complex optical field, for example at various angles. Then, the 3D Fourier space can be filled with spatial frequencies coming from the different views. Our setup consists in rotating the object under fix illumination and detection. The complex scattered field needed for tomographic reconstruction is obtained from digital holographic microscopy, using one hologram per angle of view. The method is first validated with a spherical object. Mie scattering theory is used to simulate the measured field from which the tomographic reconstruction is performed. Experimental results on microbeads are also presented. The wide capability of 3D imaging using diffraction tomography in biology is shown.