Interferometric imaging in optical astronomy

A chromatic lens-system is described which gives a magnification proportional to the inverse of the wavelength. Associated with a rotation shearing interferometer, it allows the recording of holograms of incoherent objects in white light.

Twin-image holography with spectrally broad light

A simple derivation is given for the signal-to-noise ratio (SNR) in images reconstructed from incoherent holograms. Dependence is shown to be on the hologram SNR, object complexity, and the number of pixels in the detector. Reconstruction of involved objects becomes possible with high dynamic range detectors such as charge-coupled devices. We have produced such white light holograms by means of a rotational shear interferometer combined with a chromatic corrector. A digital inverse transform recreated the object.

Signal-to-noise limitations in white light holography

In optical astronomy, images are highly degraded by atmospheric turbulence. The diameter of the seeing disk may vary from 0.2 arcseconds to 10 arcseconds or more according to weather conditions. A typical diameter is of the order of 2 arcseconds which is the angular resolution of a 6cm lens at the diffraction limit.

S. Lowenthal

Papers

Resolution and film-grain noise in fourier transform holograms recorded with coherent or spatially in coherent light