Nyquist sampling theorem in an image calculation with angular spectrum method restricts a propagation distance and a focal length of a lens. In order to avoid these restrictions, we studied suitable expressions for the image computations depending on their conditions. Additionally, a lateral scale in an observation plane can be magnified freely by using a scaled convolution in each expression.

We have observed two-photon quantum interference in a Michelson interferometer. For the first time, we experimentally demonstrated two-photon quantum interference patterns, which show the transition from nonsubwavelength interference fringes to the general subwavelength interference. At the same time, a photon bunching effect was also shown by a postselection. The ͉1, 1͘ state with a single photon in a mode corresponding to each arm of the interferometer was exclusively postselected by using path difference between two arms.

We propose and demonstrate a procedure for characterizing the quantum efficiency of a single-photon detector in the telecommunication wavelength band. Our procedure employs a bidirectional coincidence counting technique to distinguish optical component losses from the detection efficiency. The standard deviations of the measured quantum efficiencies were nearly identical to the standard deviations derived from a detection probability having a Poisson distribution.

Without moving parts, the snapshot imaging polarimeter utilizing Savart plates is capable of stable and fast measurements of spatiallly distributed Stokes parameters. To increase feasibility of the optical design, we propose modifications that enable a wider field-of view. By changing the Savar plates' configuration and improving the calibration procedure, the unwanted effects associated with the increase in the field of view can be reduced. We carried out the verification experiments of the wide field of view snapshot imaging polarimeter.