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B. E. Laubscher, B. J. Cooke, B. C. Edwards (Los Alamos National Laboratory)
Fourier Transform Heterodyne (FTH) is a detection process capable of directly imaging the transverse amplitude and phase of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned systems, Fourier Transform Heterodyne (FTH) incorporates transverse spatial encoding of the local oscillator for image capture. Appropriate selection of spatial encoding functions (basis set) allows image retrieval by way of classic Fourier manipulations. Of practical interest:
1) Imaging is accomplished on a single element detector/sensor requiring no additional scanning or moving components. 2) Because detection is governed by heterodyne principles, near quantum limited performance is achievable. 3) The concept is general with the applicable electromagnetic spectrum encompassing the RF through optical.
Although FTH is currently in its infancy, we believe this technique will provide new tools and concepts important to the development of future astronomical systems. For example:
1) An FTH-based optical or infrared interferometer (whether ground-based or space-based) can operate in direct analogy to VLBI radio astronomy systems. 2) FTH may be capable of measuring the atmospheric distortions of a target star to guide adaptive optical correction systems. 3) FTH may be used to determine the adjustments required to align a deployed structure in space and can remove aberrations from slight residual misalignments during operation.
The work to be presented will include a brief introduction of the underlying principles governing FTH imaging, followed by cursory description of a simple proof-of-concept experiment carried out using a HeNe laser, a 69 element spatial phase modulator, and a 36 term Zernike basis set. Finally, astronomical applications will be discussed.
The author(s) of this abstract have provided an email address for comments about the abstract: blaubscher@lanl.gov