Optical frequency domain

To summarize the above paragraph, trapped ions can serve as exceptional tools for new and functioning atomic clocks, in both the microwave and optical frequency domains. 

Li, J., et al. Polarization sensitive optical frequency domain imaging system for endobronchial imaging. Optics Express 23(3), 3390-3402 (2015)... 

Vakoc, B.J., et al. Tbree-dimensional microscopy of tbe tumor microenvironment in vivo using optical frequency domain imaging. Nature Medicine 15(10), 1219-1223 (2009)... 

In the optical frequency domain, superradiance in the Dieke and Bonifacio sense (Dieke 1954, Bonifacio and Lugiato 1975), i.e. with strong radiation damping, seems to have been observed in solids up to now only in photon-echo experiments, as already mentioned. The difficulty lies in the preparation of the macro-dipole in a volume smaller than ). However the recent interest in restrained geometry, e.g. the so called 2D, ID... 

Kreger, S. Calvert, S. Udd, E. Optical Frequency Domain Reflectometry for High Density Multiplexing of Multi-Axis Fiber Bragg Gratings. Proc. OFS-16, Nara, Japan (2003), p. 526... 

Interference corresponds to frequency shift of the optical spectrum towards the electronic frequency domain. 

V. Toronov, A. Webb, J. H. Choi, M. Wolf, L. Safonova, U. Wolf, and E. Grat-ton. Study of local cerebral hemodynamics by frequency-domain near-infrared spectroscopy and correlation with simultaneously acquired functional magnetic resonance imaging. Optics Express, 9 417-427, 2001. 

In frequency-domain FLIM, the optics and detection system (MCP image intensifier and slow scan CCD camera) are similar to that of time-domain FLIM, except for the light source, which consists of a CW laser and an acousto-optical modulator instead of a pulsed laser. The principle of lifetime measurement is the same as that described in Chapter 6 (Section 6.2.3.1). The phase shift and modulation depth are measured relative to a known fluorescence standard or to scattering of the excitation light. There are two possible modes of detection heterodyne and homodyne detection. 

K. S. Litwiler, P. M. Kluczynski, and F. V. Bright, Determination of the transduction mechanism for optical sensors based on rhodamine 6G impregnated perfluorosulfonate films using steady-state and frequency-domain fluorescence, Anal Chem. 63,797-802(1991). 

J. R. Alcala, I. Scott, J. Parker, B. Atwater, C. Yu, R. Fischer, and K. Bellingrath, Real time frequency-domain fiber optic sensor for intra-arterial blood oxygen measurements, in SPIE 1885, Proceedings of SPIE Biomedieal Optics (J. R. Lakowicz, ed.), Los Angeles, pp. 306-316 (1993). 

J. R. Alcala, C. Yu, and G. J. Yeh Digital phosphorimeter with frequency domain signal processing application to real time fiber optic oxygen sensing, Rev. Sci. Instrum. 64, 1554-1560 (1993). 

F. V. Bright and G. M. Hieftje, Rapid-scanning frequency domain fluorometer with picosecond time resolution, Applied Optics 26, 3526-3529 (1987). 

At the present time, two methods are in common use for the determination of time-resolved anisotropy parameters—the single-photon counting or pulse method 55-56 and the frequency-domain or phase fluorometric methods. 57 59) These are described elsewhere in this series. Recently, both of these techniques have undergone considerable development, and there are a number of commercially available instruments which include analysis software. The question of which technique would be better for the study of membranes is therefore difficult to answer. Certainly, however, the multifrequency phase instruments are now fully comparable with the time-domain instruments, a situation which was not the case only a few years ago. Time-resolved measurements are generally rather more difficult to perform and may take considerably longer than the steady-state anisotropy measurements, and this should be borne in mind when samples are unstable or if information of kinetics is required. It is therefore important to evaluate the need to take such measurements in studies of membranes. Steady-state instruments are of course much less expensive, and considerable information can be extracted, although polarization optics are not usually supplied as standard. 

All methods mentioned in Table 1 operate (typically) in the frequency domain a monochromatic optical wave is usually considered. Two basically different groups of modeling methods are currently used methods operating in the time domain, and those operating in the spectral domain. The transition between these two domains is generally mediated by the Fourier transform. The time-domain methods became very popular within last years because of their inherent simplicity and generality and due to vast increase in both the processor speed and the memory size of modem computers. The same computer code can be often used to solve many problems with rather... 

S.G. Johnson and J.D. Joannopoulos, Block-iterative frequency-domain methods for Maxwell s equations in a planewave basis , Optics Express, 8, 173-190 (2001). 

Any pulse can be described both in the time domain and in the frequency domain. In the time domain a signal may be oscillatory. The time domain behaviour is what is seen on an oscilloscope screen, because an oscilloscope is essentially an instrument for displaying a signal as a function of time. But a varying signal may also be described in terms of the components of each frequency present. This is a frequency domain description and is what is displayed by a spectrum analyser, just as an optical spectrum indicates the amount of each frequency (or wavelength) in a source of light. These two descriptions are related by a Fourier transform (Bracewell 1978), which may be written... 

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