10 μm heterodyne spectroscopy at telescopes with 1m aperture

Optical aperture synthesis with electronically connected telescopes

Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes,...

Few-photon heterodyne spectroscopy.

We perform a high-resolution Fourier transform spectroscopy of optical sources in the few-photon regime based on the phenomenon of two-photon interference in a beam splitter. From the heterodyne interferogram, between test and reference sources, it is possible to obtain the spectrum of the test source relative to that of the reference. The method proves to be a useful asset for spectral charact...

Flatfielding in spatial heterodyne spectroscopy.

Spatial heterodyne spectroscopy (SHS) is a Fourier-transform spectroscopic technique that simultaneously records all path differences using a detector array. Compared to conventional Fourier-transform spectroscopy that measures interferogram samples sequentially in the time domain, SHS is insensitive to a changing scene; however, the effects caused by differences in the detector elements and/or...

Cavity Ringdown Heterodyne Spectroscopy: High Sensitivity with Microwatt Light Power

Polarimetric calibration of large-aperture telescopes. I. Beam-expansion method.

A concept is described for the high-accuracy absolute calibration of the instrumental polarization introduced by the primary mirror of a large-aperture telescope. This procedure requires a small aperture with polarization-calibration optics (e.g., mounted on the dome) followed by a lens that opens the beam to illuminate the entire surface of the mirror. The Jones matrix corresponding to this ca...