  The image information acquisition ability of a conventional camera is usually
much lower than the Shannon Limit since it does not make use of the correlation
between pixels of image data. Applying a random phase modulator to code the
spectral images and combining with compressive sensing (CS) theory, a spectral
camera based on true thermal light ghost imaging via sparsity constraints (GISC
spectral camera) is proposed and demonstrated experimentally. GISC spectral
camera can acquire the information at a rate significantly below the Nyquist
rate, and the resolution of the cells in the three-dimensional (3D) spectral
images data-cube can be achieved with a two-dimensional (2D) detector in a
single exposure. For the first time, GISC spectral camera opens the way of
approaching the Shannon Limit determined by Information Theory in optical
imaging instruments.
