LOW COST MICROSCOPY FOR THREE DIMENSIONAL IMAGING USING DIGITAL INLINE HOLOGRAPHIC PRINCIPLE

G.Hanu Phani Ram, Vimal Prabhu Pandiyan, Renu John

Abstract: Optical microscopy is reached a new level in terms of resolution, 3-D imaging capability, flexibility of imaging different samples which increase imaging complexity and the cost.. Though established labs can afford high-end microscopes, it remains a concern in rural areas where clinics and patients cannot afford much. Semi-portable microscopy based on inline holographic setup is demonstrated where depth information as 3rd dimension can also be accessed. This setup contains only light emitting diode (LED), pinhole and charge coupled device (CCD) camera. Since laser source gives rise to speckle noise and it is also cost constraint for developing a low cost microscopy, thus it is replaced with incoherent LED source. This setup is also known as ‘lensless holography’ because there is no use of lens for imaging. In conventional inline holographic setup the sample is placed closed to the pinhole which will restrict field of view (FOV) and diffraction signature of one particle (cell) will overlap with other. To avoid overlap of diffraction signatures and to increase FOV sample was placed close to CCD sensor. To test the working of microscopy agarose microbeads were used. Optimization algorithm is used for reconstruction of object field from recorded hologram.. Thus both amplitude as well as the phase images of the microbeads is reconstructed. Instead of using microscopic objective to focus sample, autofocus algorithm is used to calculate the focused plane.

Keywords: lensless microscopy, LED, low cost

DOI: https://doi.org/10.15623/ijret.2015.0424011