Imaging without optics: Optics-less smart sensors

A new family of radiation sensors is introduced that does not require any optics. These sensors consist of array of bare radiation detectors whose angular sensitivity is determined solely by their surface absorption. This array is supplemented with a signal processing unit that uses the detector outputs to compute optimal statistical estimates of the intensities and coordinates of radiation sources. Such sensors are capable of accurate localization and intensity estimation of a given number of radiation sources and of image forming when assuming of a given number of sources in known positions. The estimation accuracy is found to depend on the detectors' noise level, on the number of detectors and on spacing between radiation sources. Advantages and limitations of proposed opticsless sensors are discussed. In addition a hypothesis is advanced that the operational principle of the sensors can shed a light on possible mechanisms of cutaneous vision in Nature and on evolution of vision.