Related papers: Intensity Interferometry revival on the C\^ote d'A…
With the current revival of interest in astronomical intensity interferometry, it is interesting to revisit the associated theory, which was developed in the 1950s and 1960s. This paper argues that intensity interferometry can be understood…
Intensity interferometry is a re-emerging interferometry tool that alleviates some of the challenges of amplitude interferometry at the cost of reduced sensitivity. We demonstrate the feasibility of intensity interferometry with fast single…
Astronomical imaging can be broadly classified into two types. The first type is amplitude interferometry, which includes conventional optical telescopes and Very Large Baseline Interferometry (VLBI). The second type is intensity…
The Narrabri intensity interferometer was successfully used until 1974 to observe 32 stars, all brighter than B=+2.5, among which some were found to have an angular diameter as small as 0.41+/-0.03 milli-arc-seconds (mas). The technique was…
After decades of experimental projects and fast-paced technical advances, optical / infrared (O/IR) interferometry has seen a revolution in the last years. The GRAVITY instrument at the VLTI with four 8 meter telescopes reaches thousand…
The original intensity interferometers were instruments built in the 1950s and 60s by Hanbury Brown and collaborators, achieving milli-arcsec resolutions in visible light without optical-quality mirrors. They exploited a then-novel physical…
Imaging Atmospheric Cherenkov Telescopes (IACTs) currently in operation feature large mirrors and order of 1 ns time response to signals of a few photo-electrons produced by optical photons. This means that they are ideally suited for…
Stellar amplitude interferometry is limited by the need to have optical distances fixed and known to a fraction of the wavelength. We suggest reviving intensity interferometry, which requires hardware which is many orders of magnitude less…
Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using…
Intensity interferometry is a technique developed many decades ago, that has recently enjoyed a renaissance thanks in part to advances in photodetector technology. We investigate the potential for long-baseline optical intensity…
Intensity interferometry removes the stringent requirements on mechanical precision and atmospheric corrections that plague all amplitude interferometry techniques at the cost of severely limited sensitivity. A new idea we recently…
Stellar intensity interferometers correlate photons within their coherence time and could overcome the baseline limitations of existing amplitude interferometers. Intensity interferometers do not rely on phase coherence of the optical…
Intensity interferometry -- the correlation of spatially separated light intensities -- has historically been an important tool for precision optical astronomical observations. However, due to the extremely narrow field of view, its scope…
We present measurements of the second order spatial coherence function of thermal light sources using Hanbury-Brown and Twiss interferometry with a digital correlator. We demonstrate that intensity fluctuations between orthogonal…
Intensity interferometry (II) exploits the second-order correlation to acquire the spatial frequency information of an object, which has been used to observe distant stars since 1950s. However, due to unreliability of employed imaging…
The current status of the high spatial resolution imaging interferometry in optical astronomy is reviewed in the light of theoretical explanation, as well as of experimental constraints that exist in the present day technology. The basic…
A long-held astronomical vision is to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, show their evolution over time, and reveal…
Most neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov…
In the last years we have operated two very similar ultrafast photon counting photometers (Iqueye and Aqueye+) on different telescopes. The absolute time accuracy in time tagging the detected photon with these instruments is of the order of…
The interferometers of Hanbury Brown and collaborators in the 1950s and 60s, and their modern descendants now being developed (intensity interferometers) measure the spatial power spectrum of the source from intensity correlations at two…