  In this paper, we propose a lensless compressive sensing imaging
architecture. The architecture consists of two components, an aperture assembly
and a sensor. No lens is used. The aperture assembly consists of a two
dimensional array of aperture elements. The transmittance of each aperture
element is independently controllable. The sensor is a single detection
element, such as a single photo-conductive cell. Each aperture element together
with the sensor defines a cone of a bundle of rays, and the cones of the
aperture assembly define the pixels of an image. Each pixel value of an image
is the integration of the bundle of rays in a cone. The sensor is used for
taking compressive measurements. Each measurement is the integration of rays in
the cones modulated by the transmittance of the aperture elements. A
compressive sensing matrix is implemented by adjusting the transmittance of the
individual aperture elements according to the values of the sensing matrix. The
proposed architecture is simple and reliable because no lens is used.
Furthermore, the sharpness of an image from our device is only limited by the
resolution of the aperture assembly, but not affected by blurring due to
defocus. The architecture can be used for capturing images of visible lights,
and other spectra such as infrared, or millimeter waves. Such devices may be
used in surveillance applications for detecting anomalies or extracting
features such as speed of moving objects. Multiple sensors may be used with a
single aperture assembly to capture multi-view images simultaneously. A
prototype was built by using a LCD panel and a photoelectric sensor for
capturing images of visible spectrum.
