Two-dimensional synthetic aperture imaging in the optical domain.

In scan-mode synthetic aperture imaging radar, spatial resolution in a range is given by a frequency-swept waveform, whereas resolution in the orthogonal direction is derived from the record of phase as the beam footprint executes linear motion over the object. We demonstrate here what is to our knowledge the first two-dimensional imaging that uses exactly this process in the optical domain for a 1 cm x 1 cm object with 90 mumx170 mum resolution.

Blind data restoration with an extracted filter function.

A method for performing blind deconvolutions on degraded images and data has been developed. The technique uses a power law relation applied to the Fourier transform of the degraded data to extract a filter function. This filter function closely resembles the point-spread function of the system and can be used to restore and enhance higher-frequency content. The process is noniterative and requires only that the point-spread function be space invariant and the transfer function be real. The algorithm has been validated by direct comparisons by use of a pseudoinverse filter with known transfer functions.

Influence of Seidel distortion on combining beams from a phased telescope array.

When beams from an array of a focal telescopes are presented to a beam-combining telescope, tilt errors of the beam wave fronts with respect to the combined wave front place limits on the achievable field of view (FOV); these limits, to the best of our knowledge, have not previously been correctly described in the literature. We show that if the front-end telescopes have just the right Seidel distortion coefficient, then tilt error does not limit the FOV. If this is not the case, at least small FOV's can still be obtained, even if the FOV is not centered on the on-axis direction.

Stacked-grid Collimators Described with Dimensionless Parameters.

The properties of a one-dimensional stacked-grid collimator can be specified by two dimensionless parameters. This is useful because a two-dimensional collimator can usually be described as two one-dimensional collimators. Plots are given that show normal-incidence transmission and FWHM angular response in terms of these parameters. Transmission is calculated with Fourier optics instead of the Fresnel-Kirchhoff integral.

Deriving the Coltman Correction for Transforming the Bar Transfer Function to the Optical Transfer Function (or the Contrast Transfer Function to the Modulation Transfer Function).

The Coltman series for obtaining the optical transfer function from measurements of the bar transfer function is mathematically derived. The bar transfer function rather than the contrast transfer function is defined so that the relation remains valid when an image exhibits phase reversal.