Experimental observation of lensless ghost imaging by measuring reflected photons

We report an experimental study of lensless ghost imaging by measuring reflected photons from an object using pseudo-thermal light radiation. A laser beam is passed through a multiple scattering medium to produce pseudo-thermal random light. Ghost image of the object is reconstructed by measuring the second-order correlation in intensity fluctuation. The study is conducted to explore the sensitivity of the imaging technique for the source parameters, i.e. coherence width and transverse size of the source. It is found that the higher the coherence width of the source higher is the visibility but the quality (resolution) becomes poor. However for higher transverse size of the source improves image quality. In addition it is verified that the observed pattern is an actual image of object. The object is chosen in the form of two very thin reflecting lines, i.e. a form of a double slit. The factors contributing to measurement uncertainty are discussed in detail. It is found that the reconstructed image gives the width of the object lines within an uncertainty of +/- 15%. (C) 2010 Elsevier Ltd. All rights reserved.