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Imaging
Published in C. R. Kitchin, Astrophysical Techniques, 2020
The greater ease of construction and operation of the intensity interferometer over the Michelson interferometer arises from its dependence upon the beat frequency of two light beams of similar wavelengths, rather than upon the actual frequency of the light. A typical value of the lower-beat frequency is 100 MHz, which corresponds to a wavelength of 3 m. Thus, the path differences for the two receivers may vary by up to about 0.3 m during an observing sequence without ill effects. Scintillation, by the same argument, is also negligible.
Interferometric Fiber-Optic Sensors
Published in Krzysztof Iniewski, Ginu Rajan, Krzysztof Iniewski, Optical Fiber Sensors, 2017
Sara Tofighi, Abolfazl Bahrampour, Nafiseh Pishbin, Ali Reza Bahrampour
The higher-order interferometers are not in the scope of this chapter. However, Hanbury HB-T interferometer that is a well-known configuration for second-order interferometry was introduced briefly in Section 3.2.2. As an example, the intensity interferometry can be used in astronomy to measure the angle between the light sources such as stellar.
Development of a digital astronomical intensity interferometer: laboratory results with thermal light
Published in Journal of Modern Optics, 2018
Nolan Matthews, David Kieda, Stephan LeBohec
When operating at the large bandwidths required by an intensity interferometry system, there is often the undesired influence of spurious correlated noise degrading the spatial coherence measurement for a given source. Noise sources are varied, from electronic cross-talk between channels in the recording system, to Cherenkov light in the atmosphere due to gamma-rays when observing stars. In the laboratory, a persistent noise source is attributed to radio-frequency (RF) pickup. This RF signal is simultaneously detected in both electronic channels producing correlated noise. Regardless of the source, if the unwanted correlated noise is stable on operational time scales it can then be measured and removed. The exact behaviour of each noise source on the correlated signal must be examined in a case-by-case basis. In this section, a general way to identify and reduce correlated noise by subtraction is presented. In our application, the temporal behaviour of the correlated signal, or correllogram, is monitored over small time-lag windows (), throughout the integration process. In the laboratory, total integration times are on the order of 5–20 min, but will be greater than one hour when observing stellar sources with telescopes.
Correlation Method of 3-D Detection of Distant Sources of Gamma Radiation and Neutrinos by Intensity Interferometry
Published in Nuclear Technology, 2023
V. I. Vysotskii, V. D. Rusov, T. N. Zelentsova, M. V. Vysotskyy, V. P. Smolyar
The proposed method for the remote location of a distant radiation source is based on the intensity interference correlation of neutrino (antineutrino) or γ-ray signal sequences from the same source measured by two or more spaced-apart distant detectors. Such method of 3-D location has never been used before, and it cannot be carried out using only one neutrino (or gamma) detector or telescope. The similar idea of an intensity interferometer based on the Brown and Twiss effect12 is used in astrophysics for measuring the angular sizes of stars.