Imaging detector of temporally coherent radiation

Abstract

We present an optical architecture and image processor capable of detecting and locating temporally coherent radiation that may be dominated by incoherent background radiation. The optical architecture makes use of a coherent light modulator that modulates light of sufficient coherence length while it leaves light of short coherence length unmodulated. The design of the coherent light modulator offers a substantially wider field of view than did past designs, permitting its application within an imaging system. The image processor synchronously detects the modulation imposed on coherent light while it rejects incoherent light fluctuations. Results of a laboratory test are presented. The system tested in the laboratory had a 26 degrees field of view and was able to detect and locate coherent radiation >30 dB below the background incoherent light level.

Low-cost detection of lasers

“…Imaging systems utilising coherence 16 and wide angle detection systems 17 have also been investigated.…”

Polarimetric description of superposing random electromagnetic fields with different spectral composition

“…1 On the other hand, a variety of spectroscopic techniques can determine the spectral density of light but cannot discriminate between different sources with overlapping spectra and, moreover, are not capable of measuring the sources' polarization properties. [2][3][4][5] In this paper we describe a procedure that not only permits the separation of radiation with a limited bandwidth from a broad spectral bandwidth (BSBW) background (without knowing a priori its spectral density) but also is able to provide a full description of the polarization properties of each component by analyzing the Stokes vectors of each component independently. An analysis in terms of the cross-spectral-density matrix and the coherency matrix of the mixture of different radiation fields provides the framework for describing both spectral and polarimetric characteristics.…”