Quantum noise of fourier-coded aperture imaging system

The single-grating aperture (SGA) and Fourier aperture (FA) both behave as variable frequency gratings to record the object spectrum directly in a Fourier domain when quantum noise is originally generated in this region. This is in contrast to a stationary coded aperture in which the noise appears in the space domain in the shadow-casting images. The noise properties of SGA and FA imaging systems, using the summation filtered backprojection reconstruction algorithm, have been determined. They are proportional to the square root of the intensity distribution of the object. From the theoretical calculations, signal-to-noise ratios of SGA and FA show the same performance as the SNR of a pinhole camera for small objects. However, for larger objects, SGA and FA show better performance than the pinhole camera. The calculated SNRs of a point and a disc object agree with the experimental results.