High-resolution lensless Fourier-transform digital holography

The aim of this work was to study the possibility of improving the resolution of digital holography. To achieve this goal we recorded digital holograms of microlines of width in the micrometer region in a lensless Fourier-transform setup. In such a way spatial frequency of the hologram can be reduced in high numerical aperture geometry. A He-Ne laser was used in the experiments. Holographic images of the test objects were reconstructed using two methods. The first one is based on fast Fourier-transform algorithm. The second one uses Monte-Carlo method. In our paper we present a comparative analysis of the reconstructed holographic images using these methods. The effects of limited resolution and nonlinearity of the CCD on the reconstructed image were included in the numerical reconstruction by multiplying the integrand of the Fresnel-Kirchhoff integral by the product of two functions, describing of the above characteristic of the CCD. This method can serve as a basis for resolution enhancement in DH via de-convolution.