Holography, a technique developed by Nobel prize winner Dennis Gabor, extends conventional imaging capability by offering the ability to view samples in 3D. With digital holography, the hologram is digitally sampled on an imaging device and transferred to a computer. Diffraction theory then permits numerical reconstruction of the image as an array of complex numbers representing the amplitude and phase of the object. Some issues exist in creating practical setups for off-axis digital holography. It should be noted that imaging in the transmission and reflection modes are possible for phase and reflective objects respectively with the technique. The need to substantially rearrange the optics each time is inconvenient when both imaging modes are constantly required. Apart from this, stray reflections are a major problem; which requires painstaking efforts to orientate the optical elements carefully.

We have recently reported a new methodology [1] that having allows for (i) convenient switch of imaging in the transmission and reflection modes, (ii) reduction in stray light reflection, (iii) immunity against environmental noise, and (iv) efficient usage of light output from the laser source. These exigencies are addressed using a free-space setup described here that applies a minimal number of optical components. This promises to be an important development in this scientific instrumentation method.