Digital holographic three-dimensional imaging spectrometry and depth imaging properties

We have studied a method to obtain both three-dimensional (3-D) spatial information and spectral information of a usual polychromatic object simultaneously by making use of a specifically designed two-wavefront folding interferometer and signal processing, including synthetic aperture technique, spectral decomposition, and 3-D image retrieval. The method uses only interferometric techniques and signal processing applied to the interferogram generated by propagated light from the measured object. We call the method the digital holographic 3-D imaging spectrometry. The method is based on measurement of 5-D interferogram. By applying synthetic aperture technique and spectral decomposition to that 5-D interferogram, one obtains a set of complex holograms of different spectral components. From these holograms, 3-D images of multiple spectral components have been retrieved on the basis of the propagation law applied to the 2-D cross-spectral densities. Decomposed continuous spectrum of each light source is also shown to demonstrate a potential applicability to identify materials of a particular part of object under illumination of white light. This paper reports experimental results in retrieving the spectral components of 3-D images of the spatially incoherent light source distribution. The results for depth imaging properties are also demonstrated.