N-slit interferometer
The N-slit interferometer is an extension of the
N-slit laser interferometer
The N-slit laser interferometer, introduced by
The disclosure of this interferometric configuration introduced the use of digital detectors to N-slit interferometry.[5][11]
Applications
Secure optical communications
These interferometers, originally introduced for applications in imaging,[6] are also useful in optical metrology and have been proposed for secure optical communications in free space,[7][12] between spacecraft. This is due to the fact that propagating N-slit interferograms suffer catastrophic collapse from interception attempts using macroscopic optical methods such as beam splitting.[7] Recent experimental developments include terrestrial intra-interferometric path lengths of 35 meters[8] and 527 meters.[9]
These large, and very large, N-slit interferometers are used to study various propagation effects including microscopic disturbances on propagating interferometric signals. This work has yielded the first observation of diffraction patterns superimposed over propagating interferograms.[9]
These diffraction patterns (as shown in the first photograph) are generated by inserting a spider web fiber (or spider silk thread) into the propagation path of the interferogram. The position of the spider web fiber is perpendicular to the propagation plane.[9]
Clear air turbulence
N-slit interferometers, using large intra interferometric distances, are detectors of clear air turbulence.[8][9] The distortions induced by clear air turbulence upon the interferometric signal are different, in both character and magnitude, from the catastrophic collapse resulting from attempted interception of optical signals using macroscopic optical elements.[13]
Expanded beam interferometric microscopy
The original application of the N-slit laser interferometer was interferometric imaging.[6][10][14] In particular, the one dimensionally expanded laser beam (with a cross section 25-50 mm wide by 10-25 μm high) was used to illuminate imaging surfaces (such as silver-halide films) to measure the microscopic density of the illuminated surface. Hence the term interferometric microdensitometer.[10] Resolution down to the nano regime can be provided via the use of interinterferometric calculations.[6] When used as a microdensitometer the N-slit interferometer is also known as a laser microdensitometer.[14]
The multiple-prism expanded laser beam is also described as an extremely elongated laser beam. The elongated dimension of the beam (25-50 mm) is in the propagation plane while the very thin dimension (in the μm regime) of the beam is in the orthogonal plane. This was demonstrated, for imaging and microscopy applications, in 1993.[6][10] Alternative descriptions of this type of extremely elongated illumination include the terms line illumination, linear illumination, thin light sheet illumination (in light sheet microscopy), and plane illumination (in selective plane illumination microscopy).
Other applications
N-slit interferometers are of interest to researchers working in atom optics,[15] Fourier imaging,[16] optical computing,[17] and quantum computing.[18]
See also
- Beam expander
- Clear air turbulence
- Diffraction from slits
- Double-slit experiment
- Free-space optical communication
- Laser communication in space
- Microscopy
- Microdensitometer
- N-slit interferometric equation
- List of laser articles
References
- ^ I. Newton, Opticks (Royal Society, London, 1704).
- ^ A. A. Michelson, Studies in Optics (Chicago University, Chicago, 1927).
- ^ R. P. Feynman, R. B. Leighton, and M. Sands, The Feynman Lectures on Physics, Vol. III (Addison Wesley, Reading, 1965).
- ^ P. A. M. Dirac, The Principles of Quantum Mechanics, 4th Ed. (Oxford, London, 1978).
- ^ a b c d F. J. Duarte and D. J. Paine, Quantum mechanical description of N-slit interference phenomena, in Proceedings of the International Conference on Lasers '88, R. C. Sze and F. J. Duarte (Eds.) (STS, McLean, Va, 1989) pp. 42–47.
- ^ ISSN 0030-4018.
- ^ S2CID 120406651.
- ^ S2CID 121521124.
- ^ S2CID 6086533.
- ^ a b c d e f g F. J. Duarte, Electro-optical interferometric microdensitometer system, US Patent 5255069 (1993) Archived 2017-10-13 at the Wayback Machine.
- ^ a b F. J. Duarte, in High Power Dye Lasers (Springer-Verlag, Berlin, 1991) Chapter 2.
- ISSN 0030-4018.
- ^ F. J. Duarte, Interferometric imaging, in Tunable Laser Applications, 2nd Edition (CRC, New York, 2009) Chapter 12.
- ^ a b F. J. Duarte, Interferometric imaging, in Tunable Laser Applications (Marcel-Dekker, New York, 1995) Chapter 5.
- ^ L-B. Deng, Theory of atom optics: Feynman path integral approach, Frontiers Phys. China 1, 47-53 (2006).
- ISSN 1050-2947.
- ^ F. J. Duarte, Tunable Laser Optics, 2nd Edition (CRC, New York, 2015) Chapter 10.
- S2CID 34750766.